Characteristics of Medicare Beneficiaries 

with Part D Coverage: NHANES 2003-

2004 Linked to 2006 Medicare Part D Data 

R Y N E P A U L O S E - R A M , P H . D 

D I V I S I O N O F H E A L T H A N D N U T R I T I O N E X A M I N A T I O N S U R V E Y S 

N A T I O N A L C E N T E R F O R H E A L T H S T A T I S T I C S 

H A N N A H R . D A Y , P H . D 

O F F I C E O F A N A L Y S I S A N D E P I D E M I O L O G Y 

N A T I O N A L C E N T E R F O R H E A L T H S T A T I S T I C S 

S T E V E N M . F R E N K , P H . D 

D I V I S I O N O F H E A L T H A N D N U T R I T I O N E X A M I N A T I O N S U R V E Y S 

N A T I O N A L C E N T E R F O R H E A L T H S T A T I S T I C S 

F E D E R A L C O M M I T T E E O N S T A T I S T I C A L M E T H O D O L O G Y 

R E S E A R C H C O N F E R E N C E 

N O V E M B E R 6 , 2 0 1 3 
Background 

 Medicare Part D (Medicare prescription drug 

benefit) 

 Federal program that subsidizes the costs of prescription drugs 

for Medicare beneficiaries 

 Enacted as part of the Medicare Modernization Act of 2003 

 Effective date: January 1, 2006 

 Most Medicare beneficiaries must affirmatively enroll in a Part 

D Plan to participate 

 Enrollment 

 2006: 21.8 million Medicare beneficiaries 

 2011: 29.6 million Medicare beneficiaries 
Background 

 Linkage to National Health and Nutrition 

Examination Surveys (NHANES) 

 Medicare enrollment and claims data are available for 

NHANES respondents who agreed to provide personal 

identification data to NCHS and for whom NCHS was able to 

match with Medicare administrative records 

 CMS provided NCHS with Medicare Part D data for 2006 and 

2007
Background 

 Unique opportunity 

 Characterize US adults who enrolled in Part D benefits during 

2006, the first year the benefit was offered 

 Potential for longitudinal research on prescription drug use 
Study Objective 

 Describe the population available from the linkage of 

NHANES 2003-2004 data to 2006 Medicare Part D 

data 

 Examine the demographic and health characteristics 

of Medicare beneficiaries aged 65+ who participated

in the 2003-2004 NHANES and who enrolled in Part 

D during 2006 
National Health and Nutrition Examination 

Survey (NHANES), 2003-2004 

 Cross-sectional survey of the civilian, noninstitutionalized U.S. population 

 Since 1999, conducted annually by CDC/NCHS 

 Uses a complex, multistage probability sample 

design 

 All ages 

 In 2003-2004 (n=10,122), oversampled: 

 Low-income persons, adolescents (12-19 years old), people 60 

years and older, non-Hispanic Blacks, and Mexican Americans 
Detailed In-Home Interview Followed by 

Standardized Physical Exam at a Mobile Center 

Interview 

• Doorstep 

screening 

• CAPI 

interviewing 

with portable 

keyboard 

Exam

• Dietary intake 

• Dental exam 

• Blood draw 

• Urine 

collection 

• Interview 
NHANES-Medicare Linkage 

NCHS 

• Linkage Eligibility 

• Sufficient personally identifiable data 

• Did not refuse 

SSA

• SSA Enumeration Verification System 

CMS 

• Exact match on SSN, full date of birth, sex 
NHANES-Medicare Linkage, continued 

 Interagency agreement 

 National Center for Health Statistics (NCHS) 

 Centers for Medicare and Medicaid Services (CMS) 

 Social Security Administration (SSA) 

 Office of the Assistant Secretary for Planning and Evaluation 

(ASPE) 

 NHANES 2003-2004  Medicare 2006 

 Denominator file 

 Medicare Part D file 

 Summary Medicare Enrollment and Claims Data (SMEC) 
Study Sample and Analysis 

 NHANES 2003-2004 linked to CMS files 

 Adults 65+ in 2003-2004 

 Interview sample weights used to account for differential 

probabilities of selection, nonresponse, and noncoverage 

 Reweighted to adjust for NHANES respondents who were not linkage 

eligible or who did not have data in the 2006 Medicare Denominator 

File 

 Estimates were age-standardized using direct method to 

2000 US Census population using three age groups: 65-

74, 75-84, and 85+ 

 Statistical analyses conducted using Stata 
Covariates 

 Socio-demographic characteristics (NHANES) 

 Age, gender, race/Hispanic ethnicity, years of education, poverty to 

income ratio (PIR) 

 Health care utilization and access to care (NHANES) 

 Have routine place for healthcare, number of times received health 

care (past year), was an overnight hospital patient (past year) 

 Self-rated health/Chronic diseases (NHANES) 

 General self-rated health (1=fair/poor; 0=excellent/very good/good) 

 Doctor ever said you have: angina, arthritis, asthma, cancer, chronic 

bronchitis, congestive heart failure, coronary heart disease, diabetes, 

emphysema, heart attack, high blood pressure, stroke, or a thyroid 

problem 

 Chronic disease index (0-1, 2-3, 4+) 
Covariates, continued 

 Use of prescription medication data in past 30 days

(NHANES) 

 Binary variable: Use at least one prescription medication 

(1=yes; 0=no) 

 Categorical variable: 0-1, 2-3, 4-5, 6+ medications

 Continuous variable: Mean number of medications 
Outcome variable 

 During 2006, respondent had at least 1 month of 

Part D enrollment (CMS data file) 
Linkage 

Figure 1. Linkage Eligibility of NHANES 2003-2004 Respondents Aged 65 Years and Older at 

Time of Interview to 2006 Medicare Part D Denominator File 

*n=2 matched at some point to the 1999-2006 Medicare Denominator File, but they did not match to the

2006 Medicare Part D Denominator File. 

Note: Percentages are not weighted. 

Source: NHANES 2003-2004; Medicare Part D Denominator File 

NHANES participants >=65 years of age 

n=1,494 

Linkage ineligible 

n=198 (13.2%) 

Linkage eligible 

n=1,296 (86.7%) 

Did not match to 2006 

Medicare Part D 

Denominator File 

n=22* (1.7% of linkage 

eligible) 

Died before 2006 

n=136 (10.5% of 

linkage eligible) 

Matched to the 2006 

Medicare Part D 

Denominator File 

n=1,138 (87.8% of 

linkage eligible) 
Results: Linkage Eligible vs. Ineligible 

% (95% CI) % 95% CI

Age

 65-74 47.3 (44.6 - 50.0) 46 (39.0 - 52.9)

 75-84 37.7 (35.1 - 40.4) 39.4 (32.6 - 46.2)

 85+ 15.0 (13.0 - 16.9) 14.6 (9.7 - 19.6)

Sex

 Female 50.8 (48.0 - 53.5) 53.5 (46.6 - 60.5)

 Male 49.2 (46.5 - 52.0) 46.5 (39.5 - 53.4)

Race/Ethnicity

 Non-Hispanic White 64.1 (61.5 - 66.7) 64.6 (58.0 - 71.3)

 Non-Hispanic Black 12.1 (10.3 - 13.9) 17.2 (11.9 - 22.4)

 Mexican-American* 19.1 (16.9 - 21.2) 11.6 (7.1 - 16.1)

Education

 Less Than a High School Degree 41.7 (39.0 - 44.4) 41.8 (34.9 - 48.8)

 High School Degree 25.3 (22.9 - 27.6) 25.5 (19.4 - 31.6)

 Some College 19.1 (17.0 - 21.3) 20.4 (14.7 - 26.1)

 College Graduate or more 13.9 (12.0 - 15.8) 12.2 (7.6 - 16.8)

Poverty Index

 Below Poverty (PIR<1) 15.4 (13.3 - 17.4) 11.9 (6.8 - 16.9)

 Low Income (PIR= 1.0 - 1.9)* 37.4 (34.7 - 40.2) 24.4 (17.7 - 31.1)

 Middle Income (PIR= 2.0 - 3.9)* 28.2 (25.7 - 30.7) 41.3 (33.6 - 48.9)

 High Income (PIR= 4.0+) 19.0 (16.8 - 21.2) 22.5 (16.0 - 29.0)

* p<0.05; adjusted Wald test

n=1,494

Linkage Eligible Linkage Ineligible
Results: Enrollment in Medicare Part D 

 Among NHANES 2003-2004 adults aged 65+ who 

matched to the 2006 Medicare Part D Denominator 

File (n=1,138) 

 56.7% were enrolled in Medicare Part D 

 Length of Enrollment 

 1-6 months: 6.9% 

 7-11 months: 29.9% 

 12 months: 63.1% 
Results: Enrollees’ Sociodemographic 

Characteristics 

Percent Enrolled in 

Medicare Part D (95% CI)

Age

 65-74 (ref) 55.2 (46.5 - 63.9)

 75-84 59.3 (51.8 - 66.7)

 85+ 56.3 (50.4 - 62.2)

Sex

 Male [ref] 52.1 (44.3 - 60.0)

 Female 60.0* (53.4 - 66.6)

Race/Hispanic Ethnicity^

 Non-Hispanic White [ref] 54.6 (47.5 - 61.8)

 Non-Hispanic Black 61.4 (47.8 - 75.0)

 Mexican-American 76.0* (66.3 - 85.7)

Education

 Less Than a High School Degree [ref] 71.7 (65.5 - 77.9)

 High School Degree 52.4* (45.0 - 59.7)

 Some College 48.0* (37.0 - 59.0)

 College Graduate or more 48.9* (41.0 - 56.8)

Poverty Index

 Below Poverty (PIR<1) [ref] 79.0 (66.6 - 91.4)

 Low Income (PIR= 1.0 - 1.9) 70.7 (66.0 - 75.4)

 Middle Income (PIR= 2.0 - 3.9) 45.6* (36.5 - 54.8)

 High Income (PIR= 4.0+) 40.9* (32.9 - 48.9)

^ Age adjusted 

* Significantly different from reference [ref] group (p<0.05)
Results: Enrollees’ Self-Rated Health and 

Chronic Disease Burden 

Percent Enrolled in 

Medicare Part D (95% CI)

Self-Rated Health

 Good/Very Good/Excellent [ref] 53.6 (47.0 - 60.3)

 Fair/Poor 64.7* (56.4 - 73.1)

Cancer 

 No [ref] 58.4 (52.6 - 64.2)

 Yes 51.3* (42.2 - 60.3)

Diabetes

 No [ref] 54.4 (47.2 - 61.6)

 Yes 66.7* (58.5 - 74.8)

* Significantly different from reference [ref] group (p<0.05)

No statistical difference for: angina, arthritis, asthma, chronic bronchitis, congestive 

heart failure, coronary heart disease, emphysema, heart attack, high blood pressure, 

stroke, or a thyroid problem 
Results: Enrollees’ Health Care Access and 

Utilization; and Prescription Medication Use 

 Health care access/utilization—No statistically 

significant differences 

 Have routine place for healthcare; number of times received health care in the 

past year; was an overnight hospital patient in the past year 

 Prescription medication use in the past 30 days—No statistically 

significant differences 

Percent Enrolled in 

Medicare Part D (95% CI)

Use at Least One Rx

 No [ref] 53.2 (43.5 - 62.9)

 Yes 56.9 (50.2 - 63.6)

Rx Categories

 0-1 Meds. [ref] 55.5 (49.0 - 62.0)

 2-3 Meds. 58.6 (47.3 - 69.9)

 4-5 Meds. 61.4 (53.7 - 69.2)

 6+ Meds. 51.2 (39.2 - 63.2)

Mean Number of RX

No Part D: 4.0 

Part D: 3.8 

(3.6 - 4.4)

(3.4 - 4.2)

* Significantly different from reference [ref] group (p<0.05)
 

Summary 

 87% of NHANES respondents 65+ in 2003-2004 

were linkage eligible 

 Mexican-Americans and low income respondents were more 

likely to be linkage eligible than ineligible 

 Middle income respondents were less likely to be linkage 

eligible than ineligible 

 76% of NHANES respondents 65+ in 2003-2004 

matched to the 2006 Medicare Part D Denominator 

File 
Summary, continued 

 About 57% of Medicare beneficiaries 65+ at the 

NHANES interview were enrolled in Medicare Part D 

 Enrollment associated with: 

 Sociodemographic characteristics: gender, education level, and 

income level 

 A few measures of baseline health: self-rated health, having 

diabetes, having cancer 

 Not associated with health care access or utilization 

 Not associated with use of prescription medication at baseline 
Limitations 

 2-3 year gap between NHANES interview and 

Medicare data 

 Do not know how respondents’ health or their prescription 

medication use changed during that period 
Future Research 

 Examine the effect of automatic enrollment on 

beneficiary characteristics 

 Examine similarities and differences in prescription 

medication use among NHANES respondents in 

2003-2004 and their use in 2006 (among Medicare 

Part D enrollees) 

 Number of medications 

 Types of medications 
Thank You for Your Time! 

For More Information: 

Steven Frenk: sfrenk@cdc.gov