U.S. Department of Health and Human Services 
Office of Inspector General 
 
 
Part D Plans 
Generally Include 
Drugs Commonly 
Used by Dual 
Eligibles: 2019 
 
OEI-05-19-00220 
Suzanne Murrin 
June 2019 
Deputy Inspector General 
 
for Evaluation and Inspections 
oig.hhs.gov  Report in Brief  U.S. Department of Health and Human Services 
June 2019 
Office  of Inspector General 
OEI-05-19-00220 
 
 
Part D Plans Generally Include Drugs 
Why OIG Did This Review 
Commonly Used by Dual Eligibles: 2019 
The ACA requires OIG to conduct a 
study of the extent to which 
What OIG Found  formularies used by Medicare Part D 
Overall, we found that the rate of Part D  plans include drugs commonly used 
plan formularies inclusion of the 196 drugs  Key Takeaway  by full-benefit dual eligible individuals 
commonly used by dual eligibles (i.e.,  Overall, we found that the  (i.e., individuals who are eligible for 
individuals who are eligible for both  rate of Part D plan  both Medicare and full Medicaid 
Medicare and Medicaid) is high, with some  formularies inclusion of the  benefits).  These individuals generally 
drugs commonly used by  get drug coverage through Medicare 
variation.  On average, Part D plan 
formularies include 97 percent of the  dual eligibles is high, with  Part D.  Pursuant to the ACA, OIG 
196 commonly used drugs.  In addition,  some variation.  Because  must annually issue a report with 
72 percent of the commonly used drugs are  some variation exists in  recommendations as appropriate.  
included by all Part D plan formularies.   formularies inclusion and  This is the ninth report that OIG has 
These results are largely unchanged from  utilization management of  produced to meet this mandate. 
these drugs, some dual 
OIGs findings for formularies reported in 
eligibles may need to make  How OIG Did This Review 
the mandated annual report from 2018, as 
well as from the findings in our reports from  additional efforts (e.g.,  For this report, we determined 
2011 through 2017.  appeal coverage decisions)  whether the 401 unique formularies 
to access the drugs they  used by the 4,073 Part D plans 
We also found that the percentage of drugs  take.    operating in 2019 cover the 200 drugs 
to which plan formularies applied utilization 
most commonly used by dual 
management tools decreased slightly 
eligibles.  We also determined the 
between 2018 and 2019.  On average, formularies applied utilization 
extent to which plan formularies 
management tools to 28 percent of the unique drugs we reviewed in 2019, a 
applied utilization management tools 
decrease of 1 percentage point from 2018. 
to those commonly used drugs.  To 
create the list of the 200 drugs most 
What OIG Concludes 
commonly used by dual eligibles, we 
Inclusion rates for the 196 drugs commonly used by dual eligibles are largely 
used data from the 2016 Medicare 
unchanged from the inclusion rates listed in our previous reports.  Part D 
Current Beneficiary Surveythe most 
formularies include roughly the same high percentage of these commonly used 
recent data available at the time of 
drugs in 2019 as they did in 2018.   
our study.  Of the top 200 drugs, 
As mandated by the Patient Protection and Affordable Care Act (ACA), OIG will  196 are eligible for Part D prescription 
continue to monitor and produce annual reports on the extent to which Part D  drug coverage, 2 are excluded from 
plan formularies cover drugs that dual eligibles commonly use.  In addition, OIG  coverage, and 1 is a medical supply 
will continue to monitor Part D plan formularies application of utilization  item covered by Part D.  One 
management tools to these drugs.  OIG has no recommendations at this time.  additional drug is eligible for Part D 
prescription drug coverage.  However, 
 
we did not include it in our analysis 
because we could not confidently 
project the use of this drug to the 
entire dual-eligible population. 
Full report can be found at oig.hhs.gov/oei/reports/oei-05-19-00220.asp   
TABLE OF CONTENTS 
BACKGROUND  1 
Methodology  6 
   
FINDINGS   
Part D plan formularies include between 89 and 100 percent of the drugs commonly used by  11 
dual eligibles 
Seventy-two percent of the drugs commonly used by dual eligibles are included in all Part D  13 
plan formularies 
The percentage of commonly used drugs to which plan formularies applied utilization  16 
management tools decreased slightly between 2018 and 2019 
   
CONCLUSION  19 
   
APPENDICES   
A:  Section 3313 of the Patient Protection and Affordable Care Act of 2010  20 
B.  List of mandated OIG reports examining dual eligibles access to drugs under Part D  21 
C.  Commonly used drugs and rates of inclusion by formularies  22 
D.  Four drugs commonly used by dual eligibles were excluded from this analysis  28 
E.  Rates at which stand-alone and Medicare Advantage prescription drug plans formularies  29 
include commonly used drugs, by region 
   
ACKNOWLEDGMENTS  31 
 
   
BACKGROUND 
Objectives 
1.  To determine the extent to which Part D plan formularies cover 
the drugs commonly used by dual eligibles. 
2.  To determine the extent to which Part D plan formularies applied 
utilization management tools to the drugs commonly used by 
dual eligibles. 
Pursuant to the Medicare Prescription Drug, Improvement, and 
Modernization Act of 2003 (MMA), comprehensive prescription drug 
coverage under Medicare Part D is available to all Medicare beneficiaries 
through prescription drug plans (PDPs) and Medicare Advantage 
prescription drug plans (MA-PDs), hereinafter referred to collectively as 
Part D plans.1   
For beneficiaries who are eligible for both Medicare and Medicaid 
(hereinafter referred to as dual eligibles), Medicare subsidizes Part D plan 
premiums, deductibles, and other cost-sharing up to a determined premium 
benchmark that varies by region.  If dual eligibles enroll in Part D plans with 
premiums higher than the regional benchmark, they are responsible for 
paying the premium amounts above that benchmark. 
To control costs and ensure the safe use of drugs, Part D plans are allowed 
to establish formularies from which they may omit certain drugs from 
prescription coverage and are allowed to control drug utilization through 
utilization management tools.2  These tools include prior authorization, 
quantity limits, and step therapy.3    
The Centers for Medicare & Medicaid Services (CMS) annually reviews 
Part D plan formularies to ensure that they include a range of drugs in a 
broad distribution of therapeutic categories or classes.  CMS also assesses 
the utilization management tools present in each formulary. 
 
1 MMA, P.L. No. 108-173  101, Social Security Act,  1860D-1(a). 
2 A formulary is a list of drugs covered by a Part D plan.  Part D plans can exclude certain 
drugs from their formularies and can control utilization for formulary-included drugs within 
certain parameters.  Social Security Act  1860D-4(b) and (c). 
3 Prior authorizationoften required for very expensive drugsrequires that physicians 
obtain approval from Part D plans to prescribe a specific drug.  Quantity limits are intended 
to ensure that beneficiaries receive the proper dose and recommended duration of drug 
therapy.  Step therapy is the practice of beginning drug therapy for a medical condition with 
the drug therapy that is the most cost-effective or safest and progressing if necessary to 
more costly or risky drug therapy. 
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OEI-05-19-00220   
 
The Medicare  Beginning in 2006, the MMA made comprehensive prescription drug 
coverage under Medicare Part D available to all Medicare beneficiaries.4   
Prescription Drug 
Medicare beneficiaries generally have the option to enroll in a PDP and 
Benefit 
receive all other Medicare benefits on a fee-for-service basis, or to enroll in 
an MA-PD and receive all of their Medicare benefits, including prescription 
drug coverage, through managed care.5  As of January 2019, approximately 
45.4 million of the 60.6 million Medicare beneficiaries were enrolled in a 
Part D plan. 
Part D plans are administered by private companiesknown as plan 
sponsorsthat contract with CMS to offer prescription drug coverage in 
one or more PDP or MA-PD regions.  CMS has designated 34 PDP regions 
and 26 MA-PD regions.  In 2019, plan sponsors offer 4,073 unique Part D 
plans, with many plan sponsors offering multiple Part D plans.  
 
Dual Eligibles Under  Approximately 12 million Medicare beneficiaries are dual eligibles.  For 
about 8.5 million dual eligibles, referred to as full benefit dual eligibles, 
Medicare Part D 
Medicaid provides full Medicaid benefits, including Medicaid-covered 
services, and may also assist beneficiaries with premiums and cost-sharing 
for Medicare fee-for-service or Medicare managed care.  For other dual 
eligibles, Medicaid does not provide Medicaid-covered services, but 
provides assistance with beneficiaries Medicare premiums or cost-sharing, 
depending on their level of income and assets.6 
Dual eligibles are a particularly vulnerable population.  Overall, most dual 
eligibles have very low incomes86 percent have annual incomes below 
150 percent of the Federal poverty level, compared with 22 percent of all 
other Medicare beneficiaries.  Additionally, dual eligibles are in worse health 
than the average Medicare beneficiaryhalf are in fair or poor health, more 
than twice the rate of others in Medicare.7  Because of their self-reported 
health needs, dual eligibles may use more prescription drugs and health 
care services in general than other Medicare beneficiaries. 
 
4 MMA, P.L. No. 108-173  101, Social Security Act,  1860D-1(a). 
5 CMS, PDBM, ch. 1,  10.1. 
6 Medicare Payment Advisory Commission (MEDPAC) and Medicaid and CHIP Payment and 
Access Commission, Data Book: Beneficiaries Dually Eligible for Medicare and Medicaid
January 2018.  Accessed at https://www.macpac.gov/wp-
content/uploads/2017/01/Jan18_MedPAC_MACPAC_DualsDataBook.pdf on April 9, 2019. 
7 Kaiser Family Foundation, Medicares Role for Dual Eligible Beneficiaries.  Accessed at 
http://www.kff.org/medicare/upload/8138-02.pdf on March 19, 2019. 
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OEI-05-19-00220   
Until December 31, 2005, dual eligibles received outpatient prescription 
drug benefits through Medicaid.  In January 2006, Medicare began covering 
outpatient prescription drugs for dual eligibles through Part D plans.8  
Medicare covers Part D plan premiums for dual eligibles up to a set 
benchmark.  The benchmark is a statutorily defined amount that is based on 
the average premium amounts for Part D plans for each region.9, 10  If dual 
eligibles enroll in Part D plans that have premiums higher than the regional 
benchmark, they are responsible for paying the premium amounts above 
that benchmark.11  
Dual eligibles assignment to Part D plans 
When individuals become eligible for both Medicare and Medicaid, CMS 
randomly assigns those individuals to PDPs unless they have elected a 
specific Part D plan or have opted out of Part D prescription drug 
coverage.12  The PDPs to which CMS assigns dual eligibles must meet 
certain requirements, such as having a premium at or below the regional 
benchmark amount and offering basic prescription drug coverage (or 
equivalent).13  Basic prescription drug coverage is defined in terms of benefit 
structure (initial coverage, coverage gap, and catastrophic coverage) and 
costs (initial deductible and coinsurance). 
Some dual eligibles may be randomly assigned to PDPs that do not cover 
the specific drugs they use.  However, unlike the general Medicare 
population, dual eligibles can switch Part D plans once per calendar quarter 
during the first 9 months of the year to find plans that cover the 
prescription drugs they require.14  When dual eligibles change plans, their 
prescription drug coverage under the new Part D plan becomes effective at 
the beginning of the following month. 
CMS annually reassigns some dual eligibles to new PDPs if their current 
PDPs will have premiums above the regional benchmark premium for the 
 
8 MMA, P.L. No. 108-173  101, Social Security Act,  1860D-1(a). 
9 Social Security Act,  1860D-14(b); 42 CFR  423.780(b)(2)(i). 
10 Dual eligibles residing in territories are not eligible to receive cost-sharing assistance from 
Medicare.  Consequently, there are no benchmarks for Part D plans offered in the territories.  
Social Security Act,  1860D-14(a)(3)(F). 
11 The ACA established a de minimis premium policy, whereby a Part D plan may elect to 
charge dual eligibles the benchmark premium amount if the Part D plans basic premium 
exceeds the regional benchmark by a de minimis amount.  Patient Protection and Affordable 
Care Act (ACA), P.L. No. 111-148  3303, Social Security Act,  1860D 14(a)(5).  For 2019, CMS 
set the de minimis amount at $2 above the regional benchmark. 
12 CMS, PDBM, ch. 3,  40.1.4. 
13 Ibid. 
14 83 Fed. Reg. 16440, 16514-19 (Apr. 16, 2018).  In general, Medicare beneficiaries can switch 
Part D plans only once a year during a defined enrollment period.  In previous years, dual 
eligibles could switch Part D plans monthly to find plans that covered the drugs they 
required.  
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OEI-05-19-00220   
following year.15  For dual eligibles who were randomly assigned to their 
current PDPs, CMS chooses new PDPs that will have premiums at or below 
the regional benchmark premium.16   For dual eligibles who elected their 
current Part D plans, CMS notifies them that their plans will have premiums 
above the regional benchmark premium.  For 2019, CMS reported 
reassigning approximately 73,000 Medicare beneficiariesincluding, but 
not exclusively, dual eligiblesbecause of premium increases. 
 
Part D Prescription  Under Part D, plans can establish formularies from which they may exclude 
drugs and control drug utilization within certain parameters.  These 
Drug Coverage 
parameters are intended to balance Medicare beneficiaries needs for 
adequate prescription drug coverage with Part D plan sponsors needs to 
contain costs.  Generally, a formulary must include at least two drugs in 
each therapeutic category or class.17, 18  In addition, Part D plans must 
include all Part-D-eligible drugs in certain categories and classes.19   
Part D plans may also control drug utilization by applying utilization 
management tools.  These tools include the following: requiring prior 
authorization to obtain drugs that are on plan formularies; establishing 
quantity limits; and requiring step therapy.  Utilization management tools 
can help Part D plans and the Part D program limit the cost of prescription 
drug coverage by placing restrictions on the use of certain drugs. 
In addition to these drug coverage decisions that Part D plans make 
regarding individual formularies, certain categories of drugs are excluded 
from Medicare Part D prescription drug coverage as mandated by the 
MMA.20  For example, prescription vitamins, prescription mineral products, 
and nonprescription drugs are excluded from Part D prescription drug 
coverage.21     
Until 2013, barbiturates and benzodiazepines were excluded from Part D 
prescription drug coverage.  However, the ACA reversed this exclusion, 
 
15 CMS, PDBM, ch. 3,  40.1.5. 
16 Ibid. 
17 CMS, PDBM, ch. 6,  30.2.1.  
18 Therapeutic categories or classes classify drugs according to their most common intended 
uses.  For example, cardiovascular agents compose a therapeutic class intended to affect the 
rate or intensity of cardiac contraction, blood vessel diameter, or blood volume. 
19 Social Security Act,  1860D-4(b)(3)(G).  Current Part D policy requires sponsors to include 
in their formularies all drugs in six categories or classes: (1) antidepressants; (2) antipsychotics; 
(3) anticonvulsants; (4) immunosuppressants for treatment of transplant rejection; 
(5) antiretrovirals; and (6) antineoplastics; except in limited circumstances.  CMS, PDBM, ch. 6, 
 30.2.5.   
20 MMA, P.L. No. 108-173  101, Social Security Act,  1860D-2(e). 
21 Social Security Act  1860D-2(e)(2), 1927(d)(2). 
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removing these two drug types from the list of drug classes ineligible for 
such coverage.22, 23    
 
CMS Efforts  Formulary review 
CMS annually reviews Part D plan formularies to ensure that they include a 
To Ensure 
range of drugs in a broad distribution of therapeutic categories or classes, 
Prescription Drug 
as well as all drugs in specified therapeutic categories or classes.24  During 
Coverage  this review, CMS analyzes formularies coverage of the drug classes most 
commonly prescribed for the Medicare population.  CMS intends for Part D 
plans to cover the most widely used medications, or therapeutically 
alternative medications (i.e., drugs from the same therapeutic category or 
class), for the most common conditions.  CMS uses Part D prescription drug 
data to identify the most commonly prescribed classes of drugs.25   
CMS also assesses each formularys utilization management tools to ensure 
consistency with current industry standards and with standards that are 
widely used with drugs for the elderly and people with disabilities.26, 27  
Exceptions and appeals process 
CMS has implemented an exceptions and appeals process whereby 
beneficiaries can request coverage of nonformulary drugs or exceptions to 
utilization management tools that apply to formulary drugs.  When a Part D 
plan receives a prescribers statement supporting an exception request, the 
plan must notify the beneficiary of its determination within 72 hours or, for 
expedited requests, within 24 hours.28  If the beneficiarys plan makes an 
adverse determination, the beneficiary has the right to appeal.29  If the plan 
continues to deny the beneficiarys request, the beneficiary has additional 
appeal rights and may continue to appeal until those rights are exhausted.  
Alternatively, the beneficiary can work with his or her prescriber to 
determine whether there is an appropriate therapeutically equivalent 
alternative drug on the plans formulary. 
   
 
22 ACA, P.L. No. 111-148  2502, Social Security Act,  1927(d). 
23 CMS, Transition to Part D Coverage of Benzodiazepines and Barbiturates Beginning in 2013.  
Accessed at http://www.cms.gov/Medicare/Prescription-Drug-
Coverage/PrescriptionDrugCovContra/Downloads/BenzoandBarbituratesin2013.pdf on 
March 20, 2019. 
24 CMS, PDBM, ch. 6,  30.2.7. 
25 Ibid. 
26 Ibid.,  30.2.2. 
27 Ibid.,  30.2.7. 
28 CMS, Parts C & D Enrollee Grievances, Organization/Coverage Determinations, and Appeals 
Guidance, ch. 18,  40.5.3. 
29 Ibid.,  50. 
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Transitioning new enrollees to Part D 
CMS requires that Part D plans establish a transition process for new 
enrollees (including dual eligibles) who are transitioning to their respective 
Part D plans either from different Part D plans or from other prescription 
drug coverage.  During a Medicare beneficiarys first 90 days under a new 
Part D plan, the new plan must provide one temporary fill of a prescription 
when the beneficiary requests either a drug that is not in the plans 
formulary or a drug that requires prior authorization or step therapy under 
the formularys utilization management tools.30  The temporary fill 
accommodates the beneficiarys immediate drug needs the first time the 
beneficiary attempts to fill a prescription.  The transition period also allows 
the beneficiary time to work with his or her prescribing physician(s) to 
obtain prescriptions for therapeutically alternative drugs or to request 
a formulary exception from the Part D plan. 
 
Related OIG Work  In 2006, OIG published a report assessing the extent to which PDP 
formularies included drugs commonly used by dual eligibles under 
Medicaid.  The study found that PDP formularies included between 76 and 
100 percent of the 178 drugs commonly used by dual eligibles under 
Medicaid prior to the implementation of Part D.  Approximately half of the 
178 commonly used drugs were covered by all formularies.31   
In 2011, OIG issued the first annual mandated report examining dual 
eligibles access to drugs under Medicare Part D.  (See Appendix A for the 
statutory mandate.)  We have released an annual mandated report each 
year since then.  (See Appendix B for a list of these reports.)  The current 
report is the ninth report released. 
 
Methodology  As mandated in the ACA, this study assessed the extent to which drugs 
commonly used by dual eligibles are included by Part D plan formularies.  
To make this assessment, we evaluated formularies for Part D plans 
operating in 2019.  As part of our assessment, we included dual eligibles 
enrollment data from January 2019, the most recent enrollment data 
available from CMS at the time of our study.  We also compared the results 
of our 2019 study with those of our 2018 study.32   
The ACA did not define which drugs commonly used by dual eligibles we 
should review.  We defined drugs commonly used by dual eligibles as the 
200 drugs with the highest utilization by dual eligibles as reported in the 
Medicare Current Beneficiary Survey (MCBS)i.e., the 2016 MCBS.  We used 
 
30 CMS, PDBM, ch. 6,  30.4.4. 
31 OIG, Dual Eligibles Transition:  Part D Formularies Inclusion of Commonly Used Drugs, 
OEI-05-06-00090, January 2006. 
32 OIG, Part D Plans Generally Include Drugs Commonly Used by Dual Eligibles:  2018, 
OEI-05-18-00240, June 2018. 
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the MCBS because it contains drugs that dual eligibles received through 
multiple sources (e.g., Part D, Medicaid, and the Department of Veterans 
Affairs) and, as such, it provides a comprehensive picture of drug utilization.  
Of the 200 highest utilization drugs that we identified using the MCBS, 
196 are eligible for coverage under Part D.  In this report, we refer to these 
196 Part-D-eligible high-utilization drugs as commonly used drugs. 
For each study, OIG has gone beyond the ACAs mandate by reviewing drug 
coverage for all dual eligibles under Medicare Part D, rather than only for 
full-benefit dual eligibles.  With the data available for this study, we could 
not confidently identify and segregate full-benefit dual eligiblesand thus 
the drugs they usedfrom the total population of dual eligibles. 
In the current (2019) report and the previous six reports, we have also gone 
beyond the ACAs mandate by examining the utilization management tools 
that Part D plan formularies apply to the drugs commonly used by dual 
eligibles.  These tools may affect dual eligibles access even in cases in which 
formularies include the commonly used drugs.  Analyzing the extent to 
which Part D plan formularies apply these tools to drugs commonly used by 
dual eligibles allows us to provide a comprehensive picture of Part D plan 
formularies coverage of, and dual eligibles access to, those drugs. 
Data sources 
MCBS.  We used the 2016 MCBS Cost and Use data to create a list of the 
200 drugs with the highest utilization by dual eligibles.  The MCBS Cost and 
Use data contain information on hospitals, physicians, prescription drug 
costs, and prescription drug utilization.  The 2016 MCBS Cost and Use data 
were the most recent data available at the time of our study.  Historically, 
the list of the 200 drugs with the highest utilization by dual eligibles has 
remained largely unchanged from year to year.  The list for 2019 overlapped 
by 88 percent with the list for 2018, which in turn overlapped by 91 percent 
with the list for 2017.33  
The MCBS is a continuous, multipurpose survey that CMS conducts of a 
representative national sample of the Medicare population, including dual 
eligibles.  Sampled Medicare beneficiaries were interviewed three times per 
year and asked what drugs they were taking and whether they had started 
taking any new drugs since the previous interview.  The MCBS also includes 
Part D prescription drug events for surveyed Medicare beneficiaries.  In 
2016, the MCBS surveyed 14,778 Medicare beneficiaries, of whom 
2,057 were dual eligibles who had used prescription drugs during the year 
(out of 3,668 dual-eligible survey respondents). 
First DataBank National Drug Data File.  We used the February 2019 First 
DataBank National Drug Data File to identify the drug product information 
for the 200 drugs with the highest utilization by dual eligibles.  The National 
 
33 In 2019, we used 2016 data.  In 2018, we used 2013 data.  In 2017, we used 2012 data. 
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Drug Data File is a database that contains informationsuch as drug name, 
therapeutic category or class, and the unique combination of active 
ingredientsfor each drug as defined by a National Drug Code (NDC).34 
Part D plan data.  In January 2019, we collected from CMS the formulary 
data and the plan data for Part D plans operating in 2019.  The formulary 
data includes Part D plans formularies and utilization management tools for 
plans operating in 2019.  In 2019, there are 401 unique formularies offered 
by 4,073 Part D plans.  The plan data provides information such as the State 
in which a Part D plan is offered, whether the Part D plan is a PDP or an 
MA-PD, and whether the Part D plan premium is below the regional 
benchmark.   
We also collected 2019 enrollment data for Part D plans.  These data 
provide the number of dual eligibles enrolled in each Part D plan as of 
January 2019. 
Determining the most commonly used drugs 
To determine the drugs most commonly used by dual eligibles, we took the 
following steps: 
1.  We created a list of all drugs reported by dual eligibles surveyed in 
the 2016 MCBS.  We excluded respondents from territories because 
they are not eligible to receive cost-sharing assistance under Part D.  
The MCBS listed 143,913 drug events for 2,057 dual eligibles who did 
not reside in territories.35   
2.  We collapsed this list to a list of drugs based on their active 
ingredients, using the Ingredient List Identifier located in First 
DataBanks National Drug Data File.  For example, a multiple source 
drug such as fluoxetine hydrochloride (the active ingredient for the 
brand-name drug Prozac) has only one entry on our list, covering all 
strengths of both the brand-name drug Prozac and the available 
generic versions of fluoxetine hydrochloride.  From this point 
forward, unless otherwise stated, we will use the term drug to refer 
to any drug in the same Ingredient List Identifier category, and the 
term unique drug to refer to an NDC corresponding to a drug, as 
a given drug can have multiple NDCs.  This process left 143,913 drug 
events associated with 829 drugs. 
3.  We ranked the 829 drugs by frequency of utilization, weighting the 
drug-event information from MCBS by sample weight. 
 
34 An NDC is a three-part universal identifier that specifies the drug manufacturers name, 
the drug form and strength, and the package size. 
35 For the purposes of this report, a drug event is an MCBS survey response indicating that 
the responding beneficiary took a specific drug at least once in 2016.  For example, 
one MCBS survey respondent reported taking omeprazole six times in 2016.  We counted this 
beneficiary/drug combination as six drug events. 
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4.  We selected the 200 drugs with the highest utilization by dual 
eligibles.  For a full list of the top 200 drugs, see Appendix C. 
5.  We removed all drugs not covered under Part D.  Of the 200 drugs 
with the highest utilization, 196 are eligible under Part D.  Two fall 
into a drug category excluded under Part D.  (For details on the two 
drugs excluded under Part D, see Appendix D.)  Two additional 
drugs are eligible for Part D prescription drug coverage.  However, 
we did not include one of these two in our analysis because
although it is eligible under Part DMedicare considers it to be 
a medical supply item.  We did not include the other drug in our 
analysis because we could not confidently project the use of this 
drug to the entire dual-eligible population.  
Formulary analysis 
We analyzed the 401 unique Part D plan formularies to determine their rates 
of inclusion of the 196 drugs commonly used by dual eligibles.  We counted 
a drug as included in a Part D plans formulary if the formulary included the 
active ingredient.   
Low rates of inclusion by formularies.  We determined which of the 
196 commonly used drugs had low rates of inclusion by formularies by 
counting how many of the 401 formularies covered each drug.  We 
considered a drug to have a low rate of inclusion if it was included by 
75 percent or less of formularies.  For such drugs, we counted the number 
of drugs (if any) that each formulary covered in the same therapeutic 
category or class.   
We conducted this analysis to ensure that dual eligibles have access to 
therapeutically similar drugs.  We also conducted additional research to 
identify potential reasons why some of the 196 commonly used drugs were 
included by 75 percent or less of formularies. 
Utilization management tools.  We determined the extent to which Part D 
plans apply utilization management tools to the 196 drugs that we reviewed.  
The tools that we reviewed are prior authorization, quantity limits, and step 
therapy. 
To determine the extent to which Part D plan formularies applied utilization 
management tools to the 196 commonly used drugs, we conducted an 
analysis of the NDCs that correspond to the commonly used drugs.  Part D 
plan formularies do not apply utilization management tools at the active 
ingredient level.  Rather, Part D plan formularies apply utilization 
management tools at a more specific level that identifies whether a drug is 
brand-name or generic and its dosage form, strength, and route of 
administration, irrespective of package size.  To conduct this analysis, we 
determined the NDCs (unique drugs) associated with each of the 
196 commonly used drugs that are on each Part D formulary.  We then 
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calculated the percentage of unique drugs to which each Part D plan 
formulary applies utilization management tools. 
Enrollment analysis 
We weighted the formulary analysis by dual-eligible enrollment and 
weighted the analysis of utilization management tools by both dual-eligible 
enrollment and Medicare enrollment.  To do this, we applied enrollment 
data from January 2019 to Part D plans available in 2019. 
Data limitations 
We did not assess individual dual eligibles prescription drug use or whether 
individual dual eligibles are enrolled in Part D plans that include the specific 
drugs that each individual uses.  Because we developed our list of 
commonly used drugs by using a sample of dual eligibles who responded 
to the MCBS, a particular dual eligible might not use any of the drugs on 
our list.  However, the drugs most commonly used by dual-eligible MCBS 
survey participants in 2016 account for 89 percent of all prescriptions 
dispensed to the dual-eligible respondents in the 2016 MCBS. 
 
Standards  We conducted this study in accordance with the Quality Standards for 
Inspection and Evaluation issued by the Council of the Inspectors General on 
Integrity and Efficiency. 
   
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FINDINGS 
Part D plan  On average, Part D plan formularies include 97 percent of the drugs 
commonly used by dual eligibles.  Of the 401 unique formularies used by 
formularies include 
Part D plans in 2019, 13 formularies include 100 percent of the commonly 
between 89 and 
used drugs.  At the other end of the inclusion range, one formulary includes 
100 percent of the  89 percent of the commonly used drugs.  Exhibit 1 provides a breakdown of 
drugs commonly  the formularies inclusion rates for the drugs most commonly used by dual 
eligibles.  CMS generally requires Part D plan formularies to include at least 
used by dual 
two drugsrather than all drugsin each therapeutic category or class.  
eligibles 
Therefore, Part D plan formularies may still meet CMSs formulary 
requirements even if they do not include all of the drugs we identified as 
commonly used by dual eligibles.  
Exhibit 1:  About 80 percent of Part D plan formularies cover at least 
97 percent of the drugs commonly used by dual eligibles. 
 
Source: OIG analysis of formulary inclusion of drugs commonly used by dual eligibles, 2019. 
 
Part D plan formularies rates of inclusion of the drugs commonly used by 
dual eligibles in 2019 increased slightly from the rates in 2018.  The average 
rate of inclusion increased slightly between 2018 and 2019, from 96 percent 
to 97 percent.  The range of rates of inclusion decreased between 2018 and 
2019; rates of inclusion ranged from 85 to 100 percent in 2018, and from 
89 to 100 percent in 2019. 
Nationally, PDP and MA-PD formularies have similar rates of inclusion of the 
drugs commonly used by dual eligibles, averaging 96 percent and 
97 percent, respectively.  For PDP formularies, the rates of inclusion range 
from 89 to 99 percent.  For MA-PD formularies, the rates of inclusion range 
from 91 to 100 percent.  Seven formularies2 percent of the 401 unique 
Part D Plans Generally Include Drugs Used by Dual Eligibles: 2019  11 
OEI-05-19-00220   
formularies used by Part D plans in 2019are offered by both PDPs and 
MA-PDs. 
Regionally, all dual eligibles have the choice of a Part D plan that includes at 
least 99 percent of the commonly used drugs.  Every PDP region has a plan 
that includes at least 99 percent of the commonly used drugs, as does every 
MA-PD region.  Appendix E provides a breakdown of formularies rates of 
inclusion of the drugs by PDP and MA-PD region. 
On average, formularies for Part D plans with premiums below the 
regional benchmark include 97 percent of the drugs commonly 
used by dual eligibles 
The percentage of drugs included by Part D plans with premiums below the 
regional benchmark is important because dual eligibles are automatically 
enrolled inor annually reassigned tosuch plans.  For drugs commonly 
used by dual eligibles, formularies for such plans have rates of inclusion that 
range from 89 percent to 100 percent.  Approximately 83 percent of dual 
eligibles are enrolled in Part D plans with premiums below the regional 
benchmark. 
Most dual eligibles are enrolled in Part D plans that include at least 
90 percent of the drugs commonly used by dual eligibles 
Of the approximately 10.9 million dual eligibles enrolled in Part D plans, 
approximately 94 percent are enrolled in Part D plans that use formularies 
that include at least 90 percent of the commonly used drugs.  Six percent of 
dual eligibles are enrolled in Part D plans that use formularies that include 
less than 90 percent of these drugs.  Exhibit 2 provides a breakdown of dual 
eligibles enrollment in Part D plans by the rates at which the plans 
formularies include the commonly used drugs. 
   
Part D Plans Generally Include Drugs Used by Dual Eligibles: 2019  12 
OEI-05-19-00220   
Exhibit 2:  Most dual eligibles are enrolled in Part D plans that 
include at least 90 percent of the drugs commonly used by dual 
eligibles. 
 
Part D Plans With Formularies  Number of Dual  Percentage of Dual 
That Include:  Eligibles Enrolled  Eligibles Enrolled 
100% of commonly used drugs  171,841   2% 
95% to 99% of commonly used 
        9,578,805 
drugs  88% 
90% to 94% of commonly used 
504,582 
drugs  5% 
85% to 89% of commonly used 
625,878  
drugs  6% 
     Total               10,881,106   100%* 
Source: OIG analysis of formulary inclusion of drugs commonly used by dual eligibles and dual eligibles 
enrollment, 2019. 
* Because of rounding, percentages do not sum to 100 percent. 
 
The percentage of dual eligibles enrolled in Part D plans that include at least 
90 percent of the drugs commonly used by dual eligibles increased slightly, 
from 93 percent in 2018 to 94 percent in 2019. 
 
Seventy-two  Because most of the commonly used drugs are included in a large 
percentage of formularies, dual eligibles can be confident that regardless of 
percent of the drugs 
the Part D plan in which they are enrolled, the plans formulary will include 
commonly used by 
many of these drugs.  By drug, inclusion in formularies ranges from 
dual eligibles are  45 percent to 100 percent.  At one end of the range, there is a drug that is 
included in all  included in 45 percent of Part D plan formularies, and at the other end, 
142 drugs are included in all plan formularies.  The average rate of inclusion 
Part D plan 
in formularies is 97 percent.  Exhibit 3 shows the rates at which formularies 
formularies 
include the 196 drugs.  Appendix C lists the 196 drugs and the rates at which 
formularies include them. 
   
Part D Plans Generally Include Drugs Used by Dual Eligibles: 2019  13 
OEI-05-19-00220   
Exhibit 3:  Nearly three-quarters of the drugs commonly used by dual 
eligibles are included in all Part D plan formularies. 
Percentage of the  Percentage of the 196 Commonly Used 
401 Formularies  Drugs Included in Formularies 
72% 
100% 
(142 drugs) 
21% 
85% to 99% 
(41 drugs) 
3% 
76% to 84% 
(5 drugs) 
4% 
45% to 75% 
(8 drugs) 
100% 
    Total 
(196 drugs) 
Source: OIG analysis of formulary inclusion of drugs commonly used by dual eligibles, 2019. 
 
The rates at which formularies include the drugs commonly used by dual 
eligibles in 2019 are similar to those in 2018.  The percentage of commonly 
used drugs included in all formularies increased slightly between 2018 and 
2019, from 68 percent to 72 percent. 
Part D plan formularies include certain drugs less frequently than 
others 
Of the commonly used drugs, 4 percent (eight drugs) are included by 
75 percent or less of Part D plan formularies.  Exhibit 4 provides the 
percentage of formularies covering each of these eight drugs. 
The drugs that make up this group include both brand-name and generic 
drugs and are used to treat a variety of primary indications.  Six of the 
eight drugs are brand-name drugs, which are typically more costly than 
generic drugs.  As for the primary indications, three of the eight drugs are 
used for diabetes therapy, two are used for gastrointestinal conditions, and 
the remaining three drugs treat a variety of conditions. 
   
Part D Plans Generally Include Drugs Used by Dual Eligibles: 2019  14 
OEI-05-19-00220   
Exhibit 4:  Drugs included by 75 percent or less of Part D plan 
formularies were most frequently used for diabetes therapy and 
gastrointestinal conditions. 
Rate of 
Generic Name of Drug  Primary Indication(s)  Inclusion by 
Formularies 
Tiotropium bromide*  Chronic obstructive pulmonary disease  75% 
Omega-3 acid ethyl esters  Hypertriglyceridemia  75% 
Esomeprazole magnesium*  Dyspepsia, peptic ulcer disease, gastroesophageal  73% 
reflux disease, Zollinger-Ellison syndrome 
Insulin aspart*  Diabetes  72% 
Canagliflozin  Diabetes  58% 
Dexlansoprazole*  Gastroesophageal reflux disease  53% 
Solifenacin succinate*  Overactive bladder, incontinence  49% 
Insulin lispro*  Diabetes  45% 
Source:  OIG analysis of formulary inclusion of drugs commonly used by dual eligibles, 2019. 
* These drugs also had low rates of formulary inclusion in 2018. 
 
Although Part D formularies frequently omit these eight drugs, they all 
cover other drugs in the same respective therapeutic classes.  For each of 
these 8 drugs, 100 percent of formularies cover at least 1 drug in the same 
therapeutic class that is also on the list of 196 drugs commonly used by dual 
eligibles. 
The number of drugs included by 75 percent or less of formularies 
decreased from 12 in 2018 to 8 in 2019.  There are six drugs with low 
inclusion rates in 2019 that were also on the list of commonly used drugs 
with low inclusion rates in our 2018 report; we note these six drugs with 
asterisks in Exhibit 4 (above).  Five of these six drugs were also on the list of 
drugs with low inclusion rates in our 2017 report. 
There are multiple potential reasons why a commonly used drug might be 
included by 75 percent or less of formularies: 
  In the case of two of the eight drugsinsulin lispro and insulin 
aspartFDA has issued MedWatch Safety Alerts because of the 
drugs delivery systems, which can vary and sometimes result in 
Part D Plans Generally Include Drugs Used by Dual Eligibles: 2019  15 
OEI-05-19-00220   
situations in which patients do not get the insulin they think they 
injected.36, 37 
  The American Geriatrics Society  cautions against certain uses of 
proton pump inhibitor drugs (PPIs) and drugs with strong 
anticholinergic properties.  Dexlansoprazole and esomeprazole 
magnesium are PPIs, and solifenacin succinate has strong 
anticholinergic properties.38  
If a formulary does not include a particular drug, a dual eligible has three 
options, all of which require taking additional action: 
-  Obtaining a therapeutically equivalent alternative drug that is included 
by the plans formulary.  (This option necessitates getting a new 
prescription from the dual eligibles doctor.) 
-  Going through an appeals process to obtain coverage of 
a nonformulary drug by submitting a statement of medical necessity 
from the dual eligibles physician.39 
-  Switching to a Part D plan with a formulary that does include the drug.  
Dual eligibles can make such a switch once per calendar quarter during 
the first 9 months of the year, with the new coverage becoming effective 
the following month.40 
 
The percentage of  For the unique drugs that compose the list of commonly used drugs, the 
percentage to which Part D plan formularies applied utilization 
commonly used 
management tools decreased slightly, from 29 percent in 2018 to 28 percent 
drugs to which plan 
in 2019.  There is little difference between plans with premiums below the 
formularies applied  regional benchmarks and those with premiums above those benchmarks; 
formularies for the two groups of plans use utilization management tools 
utilization 
for 24 percent and 29 percent, respectively, of their drugs.  See Exhibit 5 for 
management tools 
a breakdown of the percentage of unique drugs to which Part D plan 
decreased slightly 
formularies apply utilization management tools in 2018 and 2019. 
between 2018 and 
   
2019 
 
36 FDA, Insulin aspart MedWatch Safety Alert, September 27, 2018.  Accessed at 
https://www.drugs.com/fda-alerts/1341-0.html on April 2, 2019. 
37 FDA, Insulin lispro MedWatch Safety Alert, September 27, 2018.  Accessed at 
https://www.drugs.com/fda-alerts/1349-0.html on April 2, 2019. 
38 The American Geriatrics Society, American Geriatrics Society 2015 Updated Beers Criteria for 
Potentially Inappropriate Medication Use in Older Adults, 2015. 
39 CMS, Parts C & D Enrollee Grievances, Organization/Coverage Determinations, and Appeals 
Guidance, ch. 18,  40.5. 
40 83 Fed. Reg. 16519 (April 16, 2018).  
Part D Plans Generally Include Drugs Used by Dual Eligibles: 2019  16 
OEI-05-19-00220   
Exhibit 5:  Part D plan formularies application of utilization 
management tools decreased slightly between 2018 and 2019 for 
drugs commonly used by dual eligibles. 
Percentage of Unique  Number of  Percentage of  Number of  Percentage of 
Drugs to Which  2018 Part D  2018 Part D  2019 Part D  2019 Part D 
Utilization Management  Plan  Plan  Plan  Plan 
Tools Are Applied  Formularies  Formularies  Formularies  Formularies 
Greater than 40%  78  20%  68  17% 
30% to 39%  130  34%  94  23% 
20% to 29%  90  23%  137  34% 
10% to 19%  66  17%  82  20% 
Less than 10%  22  6%  20  5% 
     Totals  386  100%  401  100%* 
    Source: OIG analysis of formulary inclusion of drugs commonly used by dual eligibles, 2019. 
    * Because of rounding, percentages do not sum to 100 percent. 
 
Although utilization management tools can restrict beneficiaries access to 
drugs, they are important tools for managing costs in Medicare and 
ensuring appropriate utilization of drugs.  For example, in 2013, CMS set 
forth expectations for reviews of opioid overutilization to help ensure that 
opioids are appropriately prescribed and used.41  
The percentage of unique drugs for which formularies applied the utilization 
management tools of quantity limits, prior authorization, or step therapy42  
changed slightly between 2018 and 2019.  Formularies apply quantity limits 
to 25 percent of drugs in 2019a decrease of 1 percentage point from 
2018required prior authorization for 4 percent of drugs, and required step 
therapy for 1 percent of unique drugs. 
The rate at which plan formularies apply specific utilization management 
tools varies widely.  In 2019, some formularies apply utilization management 
tools to very few of the unique drugs, whereas at the other end of the 
range, some apply tools to 51 percent of the unique drugs.  More 
specifically, formularies apply quantity limits to between 0 and 50 percent of 
unique drugs; require prior authorization for between less than 1 percent 
and 12 percent of unique drugs; and require step therapy for between 0 and 
8 percent. 
Looking at enrollment across plans provides a slightly different picture than 
looking only at plans themselves.  On average, plan formularies in 
2019 apply utilization management tools to 28 percent of unique drugs.  
 
41 CMS, Improving Drug Utilization Review Controls in Part D (Excerpt from Final 2013 Call 
Letter 04-02-2012).  Accessed at https://www.cms.gov/medicare/prescription-drug-
coverage/prescriptiondrugcovcontra/downloads/improving-dur-controls-in-part-d.pdf on 
April 8, 2019. 
42 See footnote 3 for explanations of quantity limits, prior authorization, and step therapy. 
Part D Plans Generally Include Drugs Used by Dual Eligibles: 2019  17 
OEI-05-19-00220   
However, dual eligibles tend to be enrolled in plans with formularies that 
apply these tools at a slightly higher rate.  In 2019, the median plan 
weighted by dual-eligible enrollment applies such tools to 32 percent of 
unique drugs; in 2018, the figure was 31 percent.  Similarly, the median plan 
weighted by overall Medicare enrollment applies these tools to 32 percent 
of unique drugs in 2019; in 2018, the figure was also 32 percent. 
Both dual eligibles and Medicare beneficiaries overall tend to be enrolled in 
plans with formularies that apply utilization management tools to between 
20 and 39 percent of unique drugs.  In 2019, 83 percent of dual eligibles and 
79 percent of Medicare beneficiaries overall were enrolled in plans with 
formularies in this range.   
In 2019, there was a substantial decrease in the percentage of Medicare 
beneficiaries who were enrolled in plans that apply utilization management 
tools to more than 40 percent of unique drugs.  In 2018, 24 percent of dual 
eligibles and 26 percent of Medicare beneficiaries overall were enrolled in 
plans that apply utilization management tools to more than 40 percent of 
unique drugs.  These figures decreased to 11 percent and 14 percent, 
respectively, in 2019.  Exhibit 6 shows enrollment in Part D plans by dual 
eligibles and Medicare beneficiaries, as broken down by the percentages at 
which the plans formularies apply utilization management tools. 
Exhibit 6: The percentage of beneficiaries who were enrolled in plans 
that apply utilization management tools to more than 40 percent of 
unique drugs decreased substantially from 2018 to 2019. 
Percentage of Unique Drugs to  Percentage  Percentage  Percentage  Percentage 
Which Utilization Management  of Dual  of Medicare  of Dual  of Medicare 
Tools Are Applied  Eligibles  Beneficiaries  Eligibles  Beneficiaries 
Enrolled,  Enrolled,  Enrolled,  Enrolled, 
2018  2018  2019  2019 
Greater than 40%  24%  26%  11%  14% 
30% to 39%  29%  37%  49%  51% 
20% to 29%  41%  29%  34%  28% 
10% to 19%  3%  4%  4%  4% 
Less than 10%  2%  3%  2%  3% 
     Totals  100%*  100%*  100%  100% 
Source: OIG analysis of formulary inclusion of drugs commonly used by Medicare beneficiaries and dual eligibles, 2019. 
* Because of rounding, percentages do not sum to 100 percent. 
 
 
 
 
Part D Plans Generally Include Drugs Used by Dual Eligibles: 2019  18 
OEI-05-19-00220   
CONCLUSION 
When establishing formularies and applying utilization management tools, 
Part D plans need to balance Medicare beneficiaries needs for adequate 
prescription drug coverage with the need to contain costs for plan sponsors 
and for the Part D program.  By law and under CMS policy, Part D plan 
formularies do not generally have to include every available drug.  Rather, 
to meet CMSs formulary requirements, they must include at least two drugs 
in each therapeutic category or class.  For example, for each of the 8 drugs 
that this report identifies as being included by 75 percent or less of Part D 
plan formularies, all Part D plan formularies cover at least 1 therapeutically 
equivalent alternative drug.  Part D plan formularies may also institute 
utilization management tools to ensure appropriate utilization as well as to 
control costs. 
For the drugs commonly used by dual eligibles, we found that the rate of 
formulary inclusion is high with some variation.  On average, Part D plan 
formularies include 97 percent of the commonly used drugs.  Part D plan 
formularies inclusion of the commonly used drugs ranges from 89 percent 
to 100 percent.  Formulary inclusion rates are similar for PDPs and MA-PDs.  
Further, formularies for Part D plans with premiums below the regional 
benchmark include the commonly used drugs at a rate similar to that of 
Part D plan formularies overall. 
Inclusion rates for the 196 drugs commonly used by dual eligibles are 
largely unchanged from those listed in OIGs 2018 report.  Part D plan 
formularies include roughly the same percentage of these commonly used 
drugs in 2019 as they did in 2018.  Enrollment in plans that cover at least 
90 percent of unique drugs increased slightly, with 94 percent of dual 
eligibles enrolled in such plans in 2019 compared to 93 percent of dual 
eligibles in 2018. 
Because some variation exists in Part D plan formularies inclusion of the 
commonly used drugs and in their application of utilization management 
tools to these drugs, some dual eligibles may need to make additional 
efforts to access the drugs they take.  They could appeal prescription drug 
coverage decisions, switch prescription drugs, or switch Part D plans.  
Because these scenarios require additional effort by dual eligibles, they may 
result in administrative barriers to accessing certain prescription drugs. 
As mandated by the ACA, OIG will continue to monitor and produce annual 
reports on the extent to which Part D plan formularies cover drugs that dual 
eligibles commonly use.  In addition, OIG will continue to monitor Part D 
plan formularies application of utilization management tools to these 
drugs.  OIG has no recommendations at this time. 
   
Part D Plans Generally Include Drugs Used by Dual Eligibles: 2019  19 
OEI-05-19-00220   
APPENDIX A:  Section 3313 of the Patient 
Protection and Affordable Care Act of 2010 
SEC. 3313.  OFFICE OF THE INSPECTOR GENERAL STUDIES AND REPORTS. 
(a)  STUDY AND ANNUAL REPORT ON PART D FORMULARIES INCLUSION 
OF DRUGS COMMONLY USED BY DUAL ELIGIBLES. 
(1)  STUDY.The Inspector General of the Department of Health and 
Human Services shall conduct a study of the extent to which formularies 
used by prescription drug plans and MA-PD plans under Part D include 
drugs commonly used by full benefit dual eligible individuals (as defined in 
section 1935(c)(6) of the Social Security Act (42 U.S.C. 1396u5(c)(6)). 
(2)  ANNUAL REPORTS.Not later than July 1 of each year (beginning with 
2011), the Inspector General shall submit to Congress a report on the study 
conducted under paragraph (1), together with such recommendations as the 
Inspector General determines appropriate. 
 
   
Part D Plans Generally Include Drugs Used by Dual Eligibles: 2019  20 
OEI-05-19-00220   
APPENDIX B:  List of mandated OIG reports 
examining dual eligibles access to drugs under 
Part D 
OIG, Part D Plans Generally Include Drugs Commonly Used by Dual 
Eligibles: 2011, OEI-05-10-00390, April 2011 
OIG, Part D Plans Generally Include Drugs Commonly Used by Dual 
Eligibles: 2012, OEI-05-12-00060, June 2012 
OIG, Part D Plans Generally Include Drugs Commonly Used by Dual 
Eligibles: 2013, OEI-05-13-00090, June 2013 
OIG, Part D Plans Generally Include Drugs Commonly Used by Dual 
Eligibles: 2014, OEI-05-14-00170, June 2014 
OIG, Part D Plans Generally Include Drugs Commonly Used by Dual 
Eligibles: 2015, OEI-05-15-00120, June 2015 
OIG, Part D Plans Generally Include Drugs Commonly Used by Dual 
Eligibles: 2016, OEI-05-16-00090, June 2016 
OIG, Part D Plans Generally Include Drugs Commonly Used by Dual 
Eligibles: 2017, OEI-05-17-00160, June 2017 
OIG, Part D Plans Generally Include Drugs Commonly Used by Dual 
Eligibles: 2018, OEI-05-18-00240, June 2018 
 
   
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OEI-05-19-00220   
APPENDIX C:  Commonly used drugs and rates of 
inclusion by formularies 
The 200 drugs with the highest utilization by dual eligibles. 
*Sample is from the 2016 MCBS.  Projections and confidence intervals are derived from its survey methodology. 
95-Percent Confidence  Number of  Percentage of 
Projected 
Sample  Interval*  Formularies  Formularies 
Generic Name  Drug 
Size*  Lower  Upper  Including  Including 
Events* 
Bound  Bound  Drug  Drug 
Lisinopril  3,386  27,850,481  24,046,004  31,654,958  401  100% 
Atorvastatin Calcium  3,019  25,420,433  21,330,684  29,510,182  401  100% 
Levothyroxine Sodium  4,050  24,508,930  21,463,834  27,554,026  401  100% 
Omeprazole  3,337  23,357,611  19,510,241  27,204,982  401  100% 
Amlodipine Besylate  3,289  22,803,499  19,007,241  26,599,756  401  100% 
Furosemide  3,920  20,593,234  17,023,240  24,163,227  401  100% 
Metformin HCl  2,295  20,479,281  17,145,182  23,813,379  401  100% 
Gabapentin  3,101  19,595,402  16,258,279  22,932,525  401  100% 
Simvastatin  2,140  17,362,394  14,021,310  20,703,478  401  100% 
Hydrocodone/Acetaminophen  2,507  14,750,626  11,855,549  17,645,703  401  100% 
Potassium Chloride  2,645  14,567,534  11,539,364  17,595,704  401  100% 
Metoprolol Tartrate  2,095  13,429,329  11,035,094  15,823,564  401  100% 
Albuterol Sulfate  1,708  12,770,739  10,504,145  15,037,334  401  100% 
Losartan Potassium  1,652  12,296,175  9,786,298  14,806,053  401  100% 
Hydrochlorothiazide  1,429  12,275,939  9,589,143  14,962,736  401  100% 
Clopidogrel Bisulfate  1,432  10,739,161  8,769,906  12,708,415  401  100% 
Tramadol HCl  1,483  9,630,284  6,803,010  12,457,558  401  100% 
Pantoprazole Sodium  1,389  9,276,931  7,266,364  11,287,499  401  100% 
Carvedilol  1,219  9,209,899  7,398,466  11,021,332  401  100% 
Insulin Glargine,hum.Rec.Anlog  1,222  8,789,600  6,595,928  10,983,271  400  100% 
Trazodone HCl  1,378  8,759,142  6,746,466  10,771,817  401  100% 
Pravastatin Sodium  1,057  8,665,980  6,924,664  10,407,296  401  100% 
Fluticasone Propionate  1,226  8,302,257  6,347,364  10,257,151  401  100% 
Alprazolam  1,317  8,294,408  6,105,502  10,483,313  383  96% 
Metoprolol Succinate  1,207  7,941,013  6,270,083  9,611,944  401  100% 
Tamsulosin HCl  1,107  7,867,363  5,624,728  10,109,997  401  100% 
Sertraline HCl  1,388  7,725,380  6,108,531  9,342,229  401  100% 
Ranitidine HCl  1,093  7,356,870  5,476,829  9,236,911  401  100% 
Atenolol  818  7,316,546  5,175,566  9,457,526  401  100% 
 
continued on next page 
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OEI-05-19-00220   
The 200 drugs with the highest utilization by dual eligibles, continued. 
95-Percent Confidence  Number of  Percentage of 
Projected 
Sample  Interval*  Formularies  Formularies 
Generic Name  Drug 
Size*  Including  Including 
Lower  Upper 
Events* 
Drug  Drug 
Bound  Bound 
Warfarin Sodium  1,588  7,019,520  4,840,021  9,199,020  401  100% 
Clonazepam  1,087  6,958,062  5,061,789  8,854,334  401  100% 
Oxycodone  8,640,349 
5,069,736 
HCl/Acetaminophen  1,070  6,855,042  401  100% 
Glipizide  888  6,641,316  4,792,375  8,490,256  401  100% 
Citalopram Hydrobromide  1,233  6,430,604  5,035,854  7,825,353  401  100% 
Rosuvastatin Calcium  750  6,288,726  4,933,855  7,643,597  398  99% 
Meloxicam  891  6,281,028  4,664,766  7,897,290  401  100% 
Prednisone  970  6,017,697  4,588,246  7,447,149  401  100% 
Escitalopram Oxalate  1,094  5,917,196  3,913,700  7,920,692  401  100% 
Mirtazapine  1,271  5,749,407  4,093,455  7,405,359  401  100% 
Nystatin  1,279  5,730,694  3,794,193  7,667,194  401  100% 
Esomeprazole Magnesium  868  5,698,688  3,787,931  7,609,444  293  73% 
Montelukast Sodium  829  5,647,132  4,233,914  7,060,350  401  100% 
Sitagliptin Phosphate  809  5,596,858  3,933,417  7,260,299  382  95% 
Quetiapine Fumarate  1,201  5,494,746  4,200,817  6,788,674  401  100% 
Duloxetine HCl  991  5,425,011  3,993,781  6,856,241  401  100% 
Pregabalin  771  5,388,711  3,680,388  7,097,033  401  100% 
Bupropion HCl  787  5,275,580  3,585,019  6,966,141  401  100% 
Lorazepam  1,074  5,196,624  3,739,256  6,653,991  401  100% 
Allopurinol  693  5,136,337  3,566,049  6,706,624  401  100% 
Divalproex Sodium  1,022  5,054,227  3,118,907  6,989,546  401  100% 
Fluoxetine HCl  715  4,712,271  3,408,959  6,015,583  401  100% 
Donepezil HCl  1,172  4,508,761  3,577,598  5,439,925  401  100% 
Diltiazem HCl  698  4,474,168  3,308,384  5,639,952  401  100% 
Alendronate Sodium  519  4,301,802  2,539,710  6,063,894  401  100% 
Oxycodone HCl  764  4,263,872  3,188,913  5,338,831  400  100% 
Fluticasone/Salmeterol  608  4,173,172  2,598,441  5,747,903  392  98% 
Memantine HCl  1,085  4,089,086  3,102,076  5,076,096  401  100% 
Tiotropium Bromide  505  4,086,634  2,942,265  5,231,004  299  75% 
Oxybutynin Chloride  670  3,932,356  2,945,295  4,919,417  401  100% 
Amitriptyline HCl  508  3,889,871  2,256,534  5,523,207  401  100% 
Insulin Aspart  590  3,780,610  2,306,871  5,254,350  289  72% 
Zolpidem Tartrate  503  3,767,884  2,729,718  4,806,050  393  98% 
Diclofenac Sodium  591  3,741,357  2,435,370  5,047,344  401  100% 
Venlafaxine HCl  575  3,707,037  2,365,840  5,048,233  401  100% 
 
continued on next page 
Part D Plans Generally Include Drugs Used by Dual Eligibles: 2019  23 
OEI-05-19-00220   
The 200 drugs with the highest utilization by dual eligibles, continued. 
95-Percent  Number of  Percentage of 
Projected 
Sample  Confidence Interval*  Formularies  Formularies 
Generic Name  Drug 
Size*  Including  Including 
Lower  Upper 
Events* 
Drug  Drug 
Bound  Bound 
Spironolactone  515  3,704,252  2,180,209  5,228,296  401  100% 
Insulin Detemir  545  3,580,826  2,390,886  4,770,766  301  75% 
Ibuprofen  526  3,570,685  2,642,851  4,498,520  401  100% 
Budesonide/Formoterol Fumarate  440  3,555,410  2,534,391  4,576,429  320  80% 
Cyclobenzaprine HCl  554  3,550,448  2,101,792  4,999,103  400  100% 
Azithromycin  538  3,522,695  2,654,112  4,391,278  401  100% 
Isosorbide Mononitrate  587  3,522,387  2,452,790  4,591,984  401  100% 
Aripiprazole  651  3,487,756  2,328,461  4,647,051  401  100% 
Tizanidine HCl  503  3,481,174  2,455,064  4,507,284  401  100% 
Baclofen  604  3,468,002  2,342,499  4,593,505  401  100% 
Famotidine  677  3,428,039  2,407,301  4,448,777  398  99% 
Risperidone  750  3,369,955  2,154,973  4,584,936  401  100% 
Lovastatin  377  3,309,901  2,339,875  4,279,926  397  99% 
Lisinopril/Hydrochlorothiazide  318  3,214,188  2,210,442  4,217,933  401  100% 
Propranolol HCl  332  3,143,704  1,732,309  4,555,098  401  100% 
Levetiracetam  562  3,123,832  2,157,062  4,090,602  401  100% 
Paroxetine HCl  490  3,118,813  1,933,552  4,304,073  401  100% 
Hydralazine HCl  525  3,087,253  2,109,385  4,065,120  401  100% 
Clonidine HCl  594  3,033,303  1,963,971  4,102,635  401  100% 
Buspirone HCl  556  3,020,665  1,918,738  4,122,592  401  100% 
Finasteride  354  2,919,856  1,207,388  4,632,324  401  100% 
Glimepiride  439  2,802,493  1,749,711  3,855,276  401  100% 
Insulin Lispro  415  2,758,265  1,844,324  3,672,206  180  45% 
Latanoprost  567  2,734,063  2,029,235  3,438,891  401  100% 
Ropinirole HCl  331  2,689,120  461,475  4,916,766  401  100% 
Topiramate  412  2,668,309  1,498,248  3,838,369  401  100% 
Losartan/Hydrochlorothiazide  262  2,640,212  1,698,605  3,581,819  401  100% 
Triamterene/Hydrochlorothiazid  236  2,626,228  1,456,205  3,796,251  401  100% 
Lamotrigine  490  2,550,601  1,165,987  3,935,215  401  100% 
Rivaroxaban  337  2,493,437  1,487,339  3,499,535  395  99% 
Ezetimibe  308  2,450,095  1,388,668  3,511,523  401  100% 
Polyethylene Glycol 3350  658  2,320,953  1,742,001  2,899,905  401  100% 
Valsartan  353  2,315,246  1,404,444  3,226,049  399  100% 
Enalapril Maleate  320  2,310,159  1,555,722  3,064,595  401  100% 
Triamcinolone Acetonide  427  2,264,990  1,734,463  2,795,516  401  100% 
 
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Part D Plans Generally Include Drugs Used by Dual Eligibles: 2019  24 
OEI-05-19-00220   
The 200 drugs with the highest utilization by dual eligibles, continued. 
95-Percent  Number of  Percentage of 
Projected 
Sample  Confidence Interval*  Formularies  Formularies 
Generic Name  Drug 
Size*  Including  Including 
Lower  Upper 
Events* 
Drug  Drug 
Bound  Bound 
Ketoconazole  485  2,248,893  1,399,940  3,097,845  401  100% 
Ciprofloxacin HCl  455  2,214,730  1,820,875  2,608,584  401  100% 
Sulfamethoxazole/Trimethoprim  393  2,159,022  1,562,718  2,755,325  401  100% 
Benztropine Mesylate  564  2,143,704  1,300,494  2,986,915  401  100% 
Clobetasol Propionate  436  2,124,599  949,826  3,299,371  306  76% 
Cephalexin  391  2,095,961  1,683,934  2,507,989  401  100% 
Promethazine HCl  436  2,089,609  1,375,062  2,804,156  394  98% 
Naproxen  342  2,074,951  1,444,857  2,705,045  401  100% 
Amoxicillin  357  2,042,803  1,585,322  2,500,284  401  100% 
Acetaminophen With Codeine  351  1,998,629  1,387,210  2,610,048  401  100% 
Carbidopa/Levodopa  481  1,955,467  1,069,068  2,841,866  401  100% 
Lidocaine  322  1,938,683  1,359,282  2,518,084  401  100% 
Olanzapine  414  1,922,702  1,153,848  2,691,556  401  100% 
Fentanyl  376  1,894,430  874,454  2,914,406  401  100% 
Nitroglycerin  299  1,866,700  1,370,179  2,363,221  401  100% 
Ipratropium/Albuterol Sulfate  373  1,852,536  1,243,961  2,461,111  391  98% 
Nifedipine  248  1,837,652  1,222,742  2,452,561  395  99% 
Alcohol Antiseptic Pads  174  1,792,667  1,187,890  2,397,443   Supply Item  Supply Item 
Levofloxacin  332  1,753,771  1,417,176  2,090,366  401  100% 
Apixaban  336  1,732,183  881,299  2,583,068  397  99% 
Temazepam  262  1,710,945  811,034  2,610,856  378  94% 
Valsartan/Hydrochlorothiazide  177  1,702,228  876,089  2,528,367  398  99% 
Mirabegron  146  1,650,098  344,728  2,955,469  401  100% 
Diazepam  262  1,645,686  922,914  2,368,458  401  100% 
Bumetanide  234  1,594,403  819,956  2,368,849  401  100% 
Amoxicillin/Potassium Clav  302  1,585,856  1,260,663  1,911,049  401  100% 
Dexlansoprazole  248  1,559,760  921,332  2,198,187  211  53% 
Carbamazepine  381  1,550,565  913,692  2,187,438  401  100% 
Meclizine HCl  270  1,540,550  1,147,357  1,933,743  401  100% 
Verapamil HCl  167  1,533,824  906,439  2,161,208  401  100% 
Methylprednisolone  217  1,532,029  952,268  2,111,790  401  100% 
Lactulose  372  1,529,218  1,065,059  1,993,377  401  100% 
Fenofibrate  168  1,468,610  913,176  2,024,044  400  100% 
Gemfibrozil  100  1,457,069  780,632  2,133,505  401  100% 
Phenytoin Sodium Extended  253  1,448,258  827,668  2,068,847  401  100% 
 
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Part D Plans Generally Include Drugs Used by Dual Eligibles: 2019  25 
OEI-05-19-00220   
 
The 200 drugs with the highest utilization by dual eligibles, continued. 
95-Percent  Number of  Percentage of 
Projected 
Sample  Confidence Interval*  Formularies  Formularies 
Generic Name  Drug 
Size*  Lower  Upper  Including  Including 
Events* 
Bound  Bound  Drug  Drug 
Linagliptin  249  1,415,480  739,211  2,091,749  340  85% 
Chlorthalidone  120  1,380,192  665,169  2,095,214  401  100% 
Fenofibrate Nanocrystallized  193  1,361,460  778,890  1,944,030  394  98% 
Omega-3 Acid Ethyl Esters  173  1,356,357  640,625  2,072,089  299  75% 
Calcitriol  180  1,354,654  723,837  1,985,471  401  100% 
Celecoxib  218  1,354,652  758,003  1,951,301  382  95% 
Morphine Sulfate  274  1,344,522  777,871  1,911,172  401  100% 
Clozapine  358  1,323,079  509,570  2,136,587  401  100% 
Cyclosporine  161  1,320,808  719,963  1,921,654  401  100% 
Benazepril HCl  169  1,317,180  362,361  2,271,998  400  100% 
Solifenacin Succinate  255  1,312,625  764,201  1,861,048  197  49% 
Olmesartan Medoxomil  152  1,311,054  368,859  2,253,249  369  92% 
Digoxin  278  1,298,703  709,875  1,887,531  401  100% 
Pramipexole Di-HCl  176  1,284,762  429,580  2,139,944  401  100% 
Fluconazole  201  1,284,092  885,925  1,682,259  401  100% 
Bimatoprost  196  1,280,666  682,726  1,878,607  383  96% 
Olopatadine HCl  262  1,268,530  698,759  1,838,300  386  96% 
Ergocalciferol (Vitamin D2)**  231  1,257,693  828,978  1,686,407   Excluded  Excluded 
Sucralfate  244  1,256,644  831,677  1,681,612  401  100% 
Fluocinonide  248  1,228,328  540,609  1,916,046  396  99% 
Dicyclomine HCl  152  1,219,962  616,221  1,823,703  401  100% 
Amiodarone HCl  177  1,216,508  556,742  1,876,274  401  100% 
Liraglutide  76  1,120,275  350,024  1,890,527  383  96% 
Pioglitazone HCl  163  1,114,868  661,498  1,568,238  401  100% 
Doxycycline Hyclate  246  1,106,978  750,667  1,463,289  401  100% 
Haloperidol  295  1,056,041  568,120  1,543,961  401  100% 
Ziprasidone HCl  192  1,042,743  314,776  1,770,711  401  100% 
Metronidazole  188  1,040,527  678,009  1,403,046  401  100% 
Tolterodine Tartrate  142  1,038,033  394,281  1,681,785  386  96% 
Metoclopramide HCl  132  1,027,361  470,849  1,583,874  401  100% 
Doxazosin Mesylate  148  1,024,016  583,488  1,464,544  401  100% 
Folic Acid**  147  1,023,067  591,267  1,454,866   Excluded  Excluded 
Ondansetron HCl  207  1,007,606  718,205  1,297,007  401  100% 
Ipratropium Bromide  230  1,001,721  583,414  1,420,028  401  100% 
 
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Part D Plans Generally Include Drugs Used by Dual Eligibles: 2019  26 
OEI-05-19-00220   
 
The 200 drugs with the highest utilization by dual eligibles, continued. 
95-Percent  Percentage 
Number of 
Projected  Confidence Interval*  of 
Sample  Formularies 
Generic Name  Drug  Formularies 
Size*  Including 
Events*  Lower  Upper  Including 
Drug 
Bound  Bound  Drug 
Hydrocortisone  154  971,979  631,252  1,312,707  401  100% 
Ranolazine  107  969,876  456,124  1,483,629  401  100% 
Brimonidine Tartrate/Timolol  181  958,053  471,953  1,444,152  362  90% 
Valacyclovir HCl  126  955,249  496,956  1,413,543  401  100% 
Oxcarbazepine  258  946,963  527,534  1,366,392  401  100% 
Travoprost  179  944,930  521,586  1,368,274  378  94% 
Hydroxyzine HCl  170  932,849  520,710  1,344,988  374  93% 
Labetalol HCl  200  912,681  570,663  1,254,700  401  100% 
Sitagliptin Phos/Metformin HCl  125  906,031  349,337  1,462,725  381  95% 
Hydroxyzine Pamoate  83  893,450  115,980  1,670,919  305  76% 
Nitrofurantoin Monohyd/M-Cryst  212  886,882  595,171  1,178,593  399  100% 
Fluticasone/Vilanterol  160  878,907  496,741  1,261,073  378  94% 
Clindamycin HCl  140  873,475  458,590  1,288,359  401  100% 
Canagliflozin  91  866,496  533,136  1,199,856  232  58% 
Timolol Maleate  156  852,113  506,616  1,197,610  401  100% 
Estradiol  103  848,985  288,565  1,409,405  401  100% 
Lithium Carbonate  185  843,079  313,842  1,372,317  401  100% 
Etanercept  42  840,913  -340,267  2,022,093  Excluded  Excluded 
Metolazone  156  835,045  342,475  1,327,615  361  90% 
Clotrimazole/Betamethasone Dip  150  823,627  477,961  1,169,292  398  99% 
Fenofibrate,micronized  114  823,166  351,096  1,295,236  393  98% 
Lidocaine HCl  89  817,845  95,749  1,539,940  397  99% 
Mupirocin  213  815,323  570,354  1,060,292  401  100% 
Sumatriptan Succinate  171  810,669  405,100  1,216,237  401  100% 
Torsemide  139  799,904  203,692  1,396,116  392  98% 
Cinacalcet HCl  143  798,672  374,813  1,222,531  401  100% 
Lacosamide  197  788,150  322,011  1,254,288  401  100% 
Prasugrel HCl  53  777,539  192,455  1,362,623  381  95% 
Prednisolone Acetate  138  773,429  494,257  1,052,600  400  100% 
Niacin  88  770,009  207,602  1,332,416  401  100% 
Insulin Regular, Human  167  768,469  403,889  1,133,050  401  100% 
Dextroamphetamine/Amphetamine  172  755,954  434,391  1,077,517  401  100% 
Source:  OIG analysis of drugs commonly used by dual eligibles, 2019.  
**See Appendix D. 
   
Part D Plans Generally Include Drugs Used by Dual Eligibles: 2019  27 
OEI-05-19-00220   
APPENDIX D:  Four drugs commonly used by 
dual eligibles were excluded from this analysis 
In 2019, four drugs commonly used by dual eligibles were excluded 
from this analysis. 
Generic Name  Reason Excluded From Analysis 
Alcohol Antiseptic Pads  Supply item covered by Part D 
Vitamin or mineral product not 
Ergocalciferol (vitamin D2) 
covered under Part D 
Unable to confidently project 
Etanercept  use to entire dual-eligible 
population 
Vitamin or mineral product not 
Folic Acid 
covered under Part D 
Source: OIG analysis of formulary inclusion of drugs commonly used by dual eligibles, 2019. 
 
   
Part D Plans Generally Include Drugs Used by Dual Eligibles: 2019  28 
OEI-05-19-00220   
APPENDIX E:  Rates at which stand-alone and 
Medicare Advantage prescription drug plans 
formularies include commonly used drugs, by 
region 
Prescription drug plans (PDPs) formularies inclusion of commonly used drugs, by PDP region. 
Across all 34 PDP regions, the rates of formularies inclusion of commonly used drugs ranged from 
89 percent to 99 percent.  The average rate of inclusion was 96 percent for all PDP regions except for the 
PennsylvaniaWest Virginia region, which averaged 97 percent.  
Medicare Advantage prescription drug plans (MA-PDs) formularies inclusion of commonly used 
drugs, by MA-PD region 
  Exhibit E-1: MA-PD formularies inclusion of commonly used drugs, by MA-PD region.
 
Average Rate of 
MA-PD  Number of  Minimum  Maximum 
State(s)  Drug Inclusion 
Region*  MA-PDs  Rate  Rate 
by Formularies 
1  Maine, New Hampshire  57  98%  96%  99% 
Connecticut, Massachusetts, 
2 
Rhode Island, Vermont  116  98%  94%  99% 
3  New York  217  98%  94%  100% 
4  New Jersey  54  98%  92%  99% 
Delaware, the District of 
5 
Columbia, Maryland  39  98%  97%  100% 
6  Pennsylvania, West Virginia  198  98%  94%  100% 
7  North Carolina, Virginia  164  98%  92%  100% 
8  Georgia, South Carolina  141  99%  96%  100% 
9  Florida  380  98%  92%  100% 
10  Alabama, Tennessee  117  98%  97%  99% 
11  Michigan  83  98%  97%  99% 
12  Ohio  141  98%  94%  99% 
13  Indiana, Kentucky  138  99%  96%  99% 
14  Illinois, Wisconsin  190  98%  91%  100% 
 
continued on next page 
Part D Plans Generally Include Drugs Used by Dual Eligibles: 2019  29 
OEI-05-19-00220   
 
MA-PD formularies inclusion of commonly used drugs, by MA-PD region, continued.
 
Average Rate of 
MA-PD  Number of  Minimum  Maximum 
State(s)  Drug Inclusion 
Region*  MA-PDs  Rate  Rate 
by Formularies 
15  Arkansas, Missouri  102  99%  96%  99% 
16  Louisiana, Mississippi  87  98%  96%  99% 
17  Texas  174  98%  94%  100% 
18  Kansas, Oklahoma  70  98%  96%  99% 
Iowa, Minnesota, Montana, 
19  Nebraska, North Dakota, 
South Dakota, Wyoming  120  98%  92%  99% 
20  Colorado, New Mexico  71  99%  94%  100% 
21  Arizona  78  98%  97%  100% 
22  Nevada  41  98%  95%  99% 
Idaho, Oregon, Utah, 
23 
Washington  221  98%  94%  100% 
24  California  301  98%  94%  100% 
25  Hawaii  22  99%  97%  100% 
Source:  OIG analysis of formularies inclusion of drugs commonly used by dual eligibles, 2019. 
* Region 26, which covers Alaska, had no MA-PDs available for 2019. 
 
 
 
Part D Plans Generally Include Drugs Used by Dual Eligibles: 2019  30 
OEI-05-19-00220   
ACKNOWLEDGMENTS 
Lisa Minich served as the team leader for this study, and Jonathan Carroll 
served as the lead analyst.  Office of Evaluation and Inspections staff who 
provided support include Kevin Farber, Adam Freeman, and 
Christine Moritz.  
This report was prepared under the direction of Tom Komaniecki, Regional 
Inspector General for Evaluation and Inspections in the Chicago regional 
office, and Laura Kordish and Kelly Waldhoff, Deputy Regional Inspectors 
General.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
To obtain additional information concerning this report or to obtain copies, 
contact the Office of Public Affairs at Public.Affairs@oig.hhs.gov.  
Part D Plans Generally Include Drugs Used by Dual Eligibles: 2019  31 
OEI-05-19-00220   
ABOUT THE OFFICE OF INSPECTOR GENERAL 
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