Department of Health and Human Services 
OFFICE OF 
 
INSPECTOR GENERAL 
 
 
 
 
 
  CMS S U  
  HOULD  SE 
 
T T C
AR GETED  ACTICS TO  URB 
 
Q
  UESTIONABLE AND 
 
I P
NAPP  ROPRIATE  AYMENTS FOR 
C S  
HIROPRACTIC  ERVICES 
 
Suzanne Murrin  
Deputy Inspector General 
for Evaluation and Inspections  
  
September 2015 
OEI-01-14-00200   
   
EXECUTIVE SUMMARY:  CMS SHOULD USE TARGETED TACTICS TO CURB 
QUESTIONABLE AND INAPPROPRIATE PAYMENTS FOR CHIROPRACTIC 
SERVICES 
OEI-01-14-00200 
 
WHY WE DID THIS STUDY 
Chiropractic services have the highest rate of improper payments among Part B services, 
according to the Centers for Medicare & Medicaid Services (CMS) Comprehensive Error Rate 
Testing program.  Medicare covers chiropractic services to improve function, which it refers to 
as active treatment, but does not cover maintenance therapy, which is when further clinical  
improvement cannot be reasonably expected from ongoing treatment.  Past OIG work has found 
that between 40 and 47 percent of all paid chiropractic claims were for maintenance therapy. In 
addition, Medicare fraud cases suggest that vulnerabilities exist relative to other Medicare 
services for beneficiaries receiving chiropractic services, such as physical therapy.  
 
HOW WE DID THIS STUDY  
We analyzed paid claims for chiropractic services from 2013 to identify chiropractors who 
exhibited questionable billing using four measures:  (1) treatment suggestive of maintenance 
therapy, (2) potential sharing of beneficiaries, (3) potentially upcoded claims, and (4) unlikely 
number of services per day.   We then identified chiropractors who received high amounts of 
questionable payments.  For these chiropractors, we determined their locations, past questionable 
payments, and whether their beneficiaries received same-day physical and occupational therapy.   
We also identified inappropriate payments for claims not meeting certain Medicare requirements. 
 
WHAT WE FOUND 
In 2013, $76 million in Medicare payments for chiropractic services were questionable.  Almost 
half of the questionable payments were for claims suggestive of maintenance therapy. In 
addition, just 2 percent of chiropractors were responsible for half of the questionable payments.  
These chiropractors provided more services to more beneficiaries compared to all other 
chiropractors and were located in high-fraud areas.  Beneficiaries of these chiropractors were 
more likely to have had paid claims for physical and occupational therapy on the same day than 
were beneficiaries treated by other chiropractors, especially in high-fraud areas.  Most of these 
chiropractors also had questionable payments in a prior year.  Lastly, in 2013, Medicare 
inappropriately paid $21 million for chiropractic services that lacked a primary diagnosis 
covered by Medicare. 
 
WHAT WE RECOMMEND   
CMS should (1) establish a more reliable control for identifying active treatment, which would 
enable CMS to identify potential maintenance therapy; (2) develop and use measures to identify 
questionable payments for chiropractic services; (3) take appropriate action on the chiropractors 
with questionable payments; (4) collect overpayments based on inappropriately paid claims; and 
(5) ensure that claims are paid only for Medicare-covered diagnoses.  CMS did not concur with 
our first recommendation, citing significant obstacles and stating that new medical review 
requirements would address our concerns; we disagree because the requirements target a narrow 
group of chiropractors who are not necessarily receiving payments for maintenance 
therapy. CMS concurred with our other recommendations.    
   
   
TABLE OF CONTENTS 
 
Objectives ....................................................................................................1 

Background..................................................................................................1 

Methodology................................................................................................5 

Findings........................................................................................................8 

In 2013, $76 million of the Medicare payments for chiropractic 

services were questionable...............................................................8 

Two percent of chiropractors were responsible for half of the 

questionable payments ...................................................................11 
 
Many chiropractors with high questionable payments shared 

certain characteristics.....................................................................12 

In 2013, Medicare inappropriately paid $21 million for 

chiropractic services lacking a covered primary diagnosis ............15 

Conclusion and Recommendations ............................................................17 

Agency Comments and OIG Response..........................................20 

Appendixes ................................................................................................22 

A: Detailed Methodology .............................................................22 

B: Summary Data for Questionable and Inappropriate 

Payments. .......................................................................................27 

C: Agency Comments  ...................................................................29 

Acknowledgments......................................................................................32 

 
   
   
OBJECTIVES 
1. 	  To determine the extent to which Medicare made questionable 
payments for chiropractic services in 2013. 
2. 	  To identify and describe chiropractors with high questionable 
payments in 2013. 
3. 	  To determine the extent to which Medicare made inappropriate 
payments for chiropractic services that did not meet certain Medicare 
requirements in 2013. 
BACKGROUND 
Medicare Coverage of Chiropractic Services 
In 2013, Medicare paid $502 million for chiropractic services provided by  
45,490 chiropractors to almost 2 million beneficiaries.1  Chiropractors 
treat patients for problems of the musculoskeletal and nervous systems, 
such as headaches or pain in the back, neck, or joints.2  However,  
Medicare limits coverage of chiropractic services to manual manipulation 
treatments to treat subluxation of the spine, which is the dislocation of one 
or more spinal bones.3  Medicare covers chiropractic services to improve 
function, which it refers to as active treatment.4,5  Medicare does not 
cover maintenance therapy, which is when further clinical improvement  
cannot be reasonably expected from ongoing treatment.6    
Vulnerabilities Involving Chiropractic Services 
The Office of Inspector General (OIG) has previously found 
vulnerabilities in Medicare payments for chiropractic services.  OIG 
evaluations from 2005 and 2009 found that between 40 and 47 percent of 
all paid chiropractic claims were for maintenance therapy, which Medicare 
does not cover.7 Both reports found that when chiropractic care extends 
beyond 12 treatments in a year, it becomes increasingly likely that 
 
1 OIG analysis of 2013 Medicare Part B claims  data.  These totals are for the paid amount  
for chiropractic services. 

2 American Chiropractic Association, About Chiropractic. Accessed at 

http://www.acatoday.org/level1_css.cfm?T1ID=42 on  March 3, 2015.  

3 CMS, Medicare Benefit Policy Manual, ch. 15,   30.5 and 240. 
   
4 Social Security Act,  1862(a)(1)(A). 
 
5 CMS, Medicare Benefit Policy Manual, ch. 15,   240.1.3. 

6 CMS, Medicare Benefit Policy Manual, ch. 15,   30.5(B) and 240.1.3(A). 
 
7 OIG,  Chiropractic Services in the Medicare  Program: Payment Vulnerability Analysis, 

OEI-09-02-00530, June 2005; Inappropriate Medicare Payments for Chiropractic  
Services, OEI-07-07-00390, May 2009.  
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   1 
   
   
individual services are medically unnecessary and that chiropractors are 
often failing to comply with Medicare documentation requirements.  In 
addition, an OIG audit from November 2013 found that Medicare 
inappropriately paid over $700,000 to a California chiropractor.  These 
payments were for services that were medically unnecessary, incorrectly 
coded, undocumented, or insufficiently documented.8  
Medicare fraud cases involving chiropractors have involved services not 
rendered, medically unnecessary services, duplicate claims, and 
upcoding, as well as fraudulently billing for other health care services, 
such as physical therapy.9  For example, in 2012, a chiropractor was 
sentenced to 2 years in prison for billing over $8.5 million to Medicaid 
and Medicare over 3 years for both chiropractic and physical therapy 
services.10 In 2014, another chiropractor was sentenced to 5 years in 
prison for billing false claims to Medicare and private insurance by using 
the names of other providers whom he employed to bill for services that 
he was not qualified to perform.11     
Lastly, according to experts in chiropractic practice and fraud detection, 
other markers of potential chiropractic fraud exist.  These include 
beneficiaries with claims from multiple chiropractors (indicating potential 
kickback arrangements or medical identity theft), chiropractic claims with 
same-day services for other types of therapy (indicating that services were 
potentially not rendered or were medically unnecessary), and chiropractors 
billing for more services per day than could have reasonably been 
provided. 
Improper Payment Rate for Chiropractic Services 
Chiropractic services have had the highest rate of improper payments 
among Part B services over the last several years, according to the Centers 
for Medicare & Medicaid Services (CMS) Comprehensive Error Rate 
Testing (CERT) program.  In fact, from 2010 to 2014, the improper 
payment rate for chiropractic services increased from 43.9 to 54.1 percent 
 
8 OIG,  Diep Chiropractic Wellness, Inc., Received Unallowable Medicare Payments for 

Chiropractic Services, A-09-12-02072, November 2013. 

9 Upcoding is the practice of billing for a service that is more expensive than the service 

that was actually provided. 
 
10 Federal Bureau  of Investigation (FBI), Medicare Fraud Lands Area Chiropractor in 
 
Prison.  May 25, 2012.  Accessed at http://www.fbi.gov/houston/press-
releases/2012/medicare-fraud-lands-area-chiropractor-in-prison on May 22, 2015. 

11 FBI,  Wichita Chiropractor Sentenced in Health Care Fraud Case. November 3, 2014. 
 
Accessed at http://www.fbi.gov/kansascity/press-releases/2014/wichita-chiropractor-
sentenced-in-health-care-fraud-case on May 22, 2015. 

Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   2 
   
   
while the overall improper payment rate for Part B services remained 
between 9.9 and 12.9 percent (see Table 1). 
 
Table 1: Amount of Projected Improper Payments and Rate of Improper 
Payments for Chiropractic Services According to the CERT, 20102014  
Amount of Projected   Rate of Improper  Rate of Improper 
Year  Improper Payments for  Payments for  Payments 
Chiropractic Services   Chiropractic Services   for All Part B Services  
2010   $256,897,088   43.9%   12.9%  
2011   $263,038,123   44.1%   10.5%  
2012   $277,795,837   47.4%   9.9%  
2013   $273,488,430   51.7%   10.5%  
2014   $303,816,558   54.1%   12.1%  
Source:  CMS, Supplementary Appendices for  the  Medicare  Fee-for-Service Improper Payments Reports for  20102014.  
The CERT program estimates payments that did not meet Medicare 
coverage, coding, and billing rules.12  CMS determines the improper 
payment rate by reviewing a sample of medical records.  The five major 
error categories are: no documentation, insufficient documentation, lack 
of medical necessity, incorrect coding, and other (i.e., errors that do not fit 
into the other categories). For chiropractic services, the improper payment 
rate has increasingly resulted from insufficient documentation.13    
 
Medicare Coverage Requirements for Chiropractic Services  
Diagnosis codes for chiropractic services. Medicare requires that 
chiropractic claims have a primary diagnosis of subluxation for 
payment, but there is no diagnosis code that contains the word 
subluxation. CMS has instructed chiropractors to use the diagnosis 
codes that indicate nonallopathic lesions of the spine.14  Medicare 
Administrative Contractors (MACs) also issue local coverage 
determinations that define the appropriate diagnosis codes for chiropractic 
claims billed in their jurisdictions.  Claims for chiropractic services must 
contain the required diagnosis codes.   
 
12 CMS, Medicare Fee-For-Service 2013 Improper Payments Report, July 24, 2014.  
13 CMS, Supplementary Appendices for the Medicare Fee-for-Service Improper 
Payments Reports for 20102014.  The improper payment rates attributed to insufficient 
documentation by year are as follows:  2010, 39.5%; 2011, 72.9%; 2012, 76.2%;  

2013, 92.5%; 2014, 92.2%. 

14 CMS, Medicare Learning Network,  Chiropractic Services, ICN 906143, October 2013. 

Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   3 
   
   
Procedure codes for chiropractic services. Chiropractors use Current 
Procedural Terminology (CPT) codes to bill Medicare Part B.15  Medicare 
pays only for the three CPT codes for chiropractic manipulative treatment 
of the spine.16   These codes indicate the number of spinal regions treated.  
(See Table 2 for CPT codes and Figure 1 for spinal regions.)   
 
Table 2: CPT Codes for Chiropractic Services Covered by Medicare and  
Figure 1: Regions of the Spine for Chiropractic Treatment  
 
CPT Code   Description  
Treatment of one to two 
98940  
spinal regions 
Treatment of three to four 
98941  
spinal regions 
Treatment of five spinal 
98942  
regions 
Source  for Figure 1:   Spinal Column with Vertebrae, accessed at http://nphonsskeletal4.wikispaces.com/Axial+Skeleton  
on February 17, 2015.  This work is licensed under a Creative Commons Attribution-ShareAlike  3.0 Unported License. 
 
Modifications were made to  the colors and labels from the original. 
 
Active Treatment Modifier.   CMS requires that chiropractors use the 
Active Treatment (AT) modifier on a claim when providing a chiropractic 
service that is active/corrective therapy and not maintenance therapy, 
which Medicare does not cover.17  However, CMS acknowledges that the 
 
15  The five character codes and descriptions included in this report are obtained 
from Current Procedural Terminology (CPT), copyright 2012 by the American 
Medical Association (AMA). CPT is developed by  the AMA as a listing  of  
descriptive terms and five character identifying codes and modifiers for reporting 
medical services and procedures. Any use of CPT outside of this report should refer  
to the most current version of the Current Procedural Terminology available from 
AMA. Applicable FARS/DFARS apply.  
16 CMS, Medicare Benefit Policy Manual Transmittal 23,  Revised Requirements for 
Chiropractic Billing of Active/Corrective Treatment and Maintenance Therapy (Change  
Request 3449, Oct. 8, 2004); CMS, MLN Matters No. MM3449  (Oct. 8, 2004). 
17 CMS, Medicare Benefit Policy Manual, ch. 15,   240.1.3. 
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   4 
   
   
presence of the AT modifier may not in all instances indicate that the 
service is reasonable and necessary.18  
Limits on covered services. CMS does not limit the number of 
chiropractic services that a beneficiary may receive over a given time 
period. However, some MACs have issued local coverage determinations 
that limit the number of chiropractic services per beneficiary per year or 
that require medical review for services that exceed a certain threshold.  
METHODOLOGY 
This study is national in scope and is based primarily on paid Medicare 
claims for chiropractic services provided in 2013.  See 
Appendix A for a full discussion of our methodology. 
Questionable Chiropractic Payments 
We developed four measures to identify paid claims that were 
questionable. We based these measures on previous OIG reports and fraud 
investigations, interviews with experts in chiropractic practice and fraud 
detection, and our own analysis. These four measures are summarized 
below: 
Treatment Suggestive of Maintenance Therapy.  A high average number of 
claims per beneficiary per chiropractor suggests billing for services that 
were not active treatment.  Previous OIG work has found that as more 
services are provided to a beneficiary, it becomes more likely that services 
are medically unnecessary or maintenance treatment. 
Potentially Upcoded Claims.  A high average physician work relative 
value unit for a chiropractors claims suggests billing for services at a 
higher level than warranted.19  Only about 10 percent of all paid 
chiropractic services are for the highest CPT code, 98942.  Previous OIG 
work found that almost half of chiropractic services with CPT code 98942 
were upcoded.20    
Potential Sharing of Beneficiaries.  A high average percentage of a 
chiropractors beneficiaries who received services from other 
chiropractors suggests the misuse of beneficiary identification numbers.  
OIG investigations and interviews with experts informed us that 
 
18 CMS, Medicare Benefit Policy Manual, ch. 15,   240.1.3. 

19 Medicare assigns each CPT  code a physician relative value unit to establish the level 
 
of time, skill, and training to  provide the service.  A higher relative value unit takes more 

time and/or skill to provide the service and  results in a higher payment. 
 
20 OIG,  Inappropriate Medicare Payments for Chiropractic  Services. OEI-07-07-00390, 

May 2009. 
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   5 
   
   
chiropractors with a high percentage of beneficiaries receiving treatments 
from other chiropractors may be involved with fraud schemes, such as 
medical identity theft or kickback arrangements. 
Unlikely Number of Services per Day.  A high number of hours of services 
provided by a chiropractor on 1 day suggests billing for services of 
diminished quality and/or for services that were not rendered. 
We calculated these measures for each chiropractor and analyzed the 
distribution of chiropractors for each measure.  For the first three 
measures, we used a statistical technique called the Tukey method to 
identify chiropractors who were outliers compared to other chiropractors.  
For these three measures, we considered a chiropractors payments to be 
unusually high, or questionable, if they were greater than the 
75th percentile plus 1.5 times the interquartile range.21  For the fourth 
measure, we established a threshold of 16 hours per day based on our 
knowledge, experience, and discussions with experts. 
Inappropriate Chiropractic Payments  
We developed three measures to identify paid claims that did not meet 
Medicare requirements for payment.  These three measures are 
summarized below: 
Claims Lacking a Covered Primary Diagnosis. These claims lacked a 
primary diagnosis code that was covered by Medicare based on CMSs 
guidance and the local coverage determination where the chiropractic 
service was provided. 
Claims for Duplicate Services. These claims were for services provided 
on the same day for the same beneficiary with the same diagnosis and 
procedure codes and the same chiropractor. 
Claims Lacking the AT Modifier. These claims lacked the AT modifier, 
which indicates active treatment and is required for payment. 
Chiropractors with High Questionable Payments 
After calculating the total amount of questionable payments paid to each 
chiropractor, we identified chiropractors who received high amounts of 
questionable payments.  For these chiropractors, we determined their 
locations, past questionable payments, and the extent to which their 
beneficiaries received physical and occupational therapy services on the 
 
21 This is a standard exploratory method for identifying members of a population  with  
unusually high values  on a given statistic compared to the rest of the population when  no  
established benchmarks exist.  See J.W. Tukey,  Exploratory Data  Analysis, 
Addison-Wesley, 1977.  The interquartile range is the value at the 75th  percentile minus  
the value at the 25th  percentile.  
 
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   6 
   
   
same day.   We identified their locations using the ZIP Codes on their 
claims.  We identified past questionable payments by analyzing 
chiropractic claims data from 20092012 using our measures of 
questionable payment.  Finally, we analyzed Part B claims data for 
physical and occupational therapy services to determine the extent to 
which the beneficiaries of chiropractors with high questionable payments 
received physical and occupational therapy services on the same day as 
chiropractic services. 
Limitations 
We did not conduct a medical record review to determine whether 
chiropractic services were medically necessary or had been coded 
correctly.  The measures included in our analysis are not intended to be a 
comprehensive set of characteristics for identifying chiropractors with 
questionable and inappropriate payments.  Moreover, the four measures 
that identify questionable payments used in this study do not provide 
conclusive evidence of improper or fraudulent payments.  Rather, the 
measures are intended to identify Medicare payments to chiropractors that 
exceed those of other chiropractors in ways that raise program integrity 
concerns. Further investigation would be required to determine whether 
these chiropractors were paid for improper or fraudulent Medicare claims  
for chiropractic services. 
Standards 
This study was conducted in accordance with the Quality Standards for 
Inspection and Evaluation issued by the Council of the Inspectors General 
on Integrity and Efficiency.   
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   7 
   
   
FINDINGS 
In 2013, $76 million of the Medicare payments for 
chiropractic services were questionable  
Of the $502 million that Medicare paid in 2013 for chiropractic services, 
$76.1 million was for claims that were questionable based on our four 
measures of questionable payment.  Payments for these claims represent 
15 percent of the Medicare payments for chiropractic services in 2013.   
Treatment suggestive of maintenance therapy was the driver 
of questionable payments 
In total, 16 percent of chiropractors (7,191) paid by Medicare in 2013 
received questionable payments for chiropractic services.  Almost half of 
these payments were for claims suggestive of maintenance therapy, which 
we identified through high average numbers of claims per beneficiary per 
chiropractor.  Medicare does not cover maintenance therapy.  Table 3 
provides detail on our measures that identified questionable payments. 
Table 3: Chiropractors and Paid Amount by Measure of Questionable Payment in 2013* 
Percentage 
Paid Amount   of Total  Number of   Percentage of  
Measure of  Questionable Payment  
for Measure*   Paid  Chiropractors*  Chiropractors  
Amount 
Treatment Suggestive of Maintenance Therapy   $33,956,039   6.8%   1,787   3.9%  
Potential Sharing of Beneficiaries  $25,724,446   5.1%   4,216   9.3%  
Potentially Upcoded Claims  $21,291,936   4.2%   1,450   3.2%  
Unlikely Number of Services per Day  $768,964   0.2%   16  0.04%  
Total   $76,104,699   15.1%   7,191   15.8%  
Source:  OIG analysis of data from 2013 Part  B claims  for chiropractic services paid for by Medicare. 
* Because some claims exceeded the threshold for more than one  measure of questionable payment, the columns do not sum to the totals.  
The 1,787 chiropractors (4 percent) who had questionable payments for 
claims suggestive of maintenance therapy provided an average of 
25 services per beneficiary during 2013.  In contrast, all other 
chiropractors provided an average of  8 services per beneficiary during 
2013. Although we are unable to determine when a beneficiarys course 
of treatment began, the volume of services that these chiropractors 
provided to their beneficiaries suggests that the treatment was 
maintenance.22   Table 4 shows noteworthy examples of chiropractors with 
questionable payments for treatment suggestive of maintenance therapy. 
 
22 According to the  Medicare Claims Processing Manual, Pub. No. 100-04, ch.12,  
  220(D), Medicare requires that chiropractors report the date of initiation  of treatment on  
their claims.  However, this information  is not contained in CMSs National Claims  
History  file and was thus unavailable for our use.  
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   8 
   
   
 
Table 4: Examples of Chiropractors with Questionable Payments for Treatment 
Suggestive of Maintenance Therapy  
Location  Example  
Ninety-nine percent of a chiropractors payments were for claims suggestive of 
California   maintenance therapy.  Several beneficiaries  of this chiropractor each had more than 
250 visits in 2013.  
All but one of the beneficiaries seen by  a chiropractor in 2013 each had more than 
Missouri 
20 visits. These beneficiaries had an average of 172 visits with this chiropractor. 
Medicare paid a chiropractor over $205,000 for about 200 beneficiaries who had 
New York  
treatments suggestive of maintenance therapy in 2013. 
Almost two-thirds of a chiropractors beneficiaries had treatment suggestive of 
Michigan 
maintenance therapy  in 2013 (on average, around 50 visits per beneficiary). 
Source: OIG analysis of data from 2013 Part B claims for chiropractic services paid for by Medicare.  
Lastly, the use of the AT modifier to ensure that payments are made only 
for active treatment is not effective.  Every claim that we identified as 
being suggestive of maintenance therapy included the AT modifier, raising 
questions about its effectiveness as a control to ensure that Medicare pays 
only for active treatment.  Prior OIG work found that CMSs requirement 
to use the AT modifier to indicate active treatment merely resulted in an 
increase in the use of the AT modifier, rather than in reduced payments for 
 
maintenance therapy.23  Moreover, in 2013, 96 percent of all claims for 
chiropractic services that were submitted to Medicare included the AT  
modifier.24  
About $47 million in questionable payments was related to 
potential beneficiary sharing, upcoding, and unlikely number 
of services per day 
Potential sharing of beneficiaries. In 2013, Medicare paid $25.7 million 
to chiropractors who shared 52.5 percent or more of the beneficiaries they 
treated with other chiropractors.  These 4,216 chiropractors represent 
9 percent of the chiropractors paid by Medicare in 2013.  In contrast, 
chiropractors who did not have questionable payments for beneficiary 
sharing had an average of 14 percent of their beneficiaries who received 
services from other chiropractors. It is possible that beneficiaries chose to 
receive services from multiple chiropractors.  However, when high 
percentages of beneficiaries receive services from multiple chiropractors, 
 
23 OIG,  Inappropriate Medicare Payments for Chiropractic  Services.   OEI-07-07-00390, 
May 2009. 

24 This percentage includes all claims for chiropractic services performed in  2013 that 

were submitted to Medicare for payment, including those that were denied. 
 
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   9 
   
   
this has implications for the continuity of the beneficiaries care.  High 
percentages of beneficiaries who are shared among chiropractors also may 
be related to fraud schemes, such as medical identity theft or kickback 
arrangements. 
Potentially upcoded claims. Medicare paid $21.3 million to chiropractors 
whose payments had high average physician work relative value units 
(RVUs), which reflect the relative time and skill associated with furnishing 
services under the Medicare Physician Fee Schedule.25   By analyzing the 
work RVUs, we identified 1,450 chiropractors, or 3 percent, as outliers 
who were paid for chiropractic services at higher-levels than other 
chiropractors were.  Of these chiropractors, more than half had all of their 
Medicare payments for the highest level chiropractic CPT code98942 
which is an adjustment of all five regions of the spine.  In contrast, only a 
fifth of chiropractors paid by Medicare in 2013 were paid for this CPT  
code, and just 10 percent of the Medicare payments for chiropractic 
services were for this code. Although some chiropractors may specialize 
in complex conditions, previous OIG work found that almost half of the 
claims for chiropractic services with CPT code 98942 were upcoded.26   
Unlikely number of services per day. Medicare paid $768,964 to 
16 chiropractors for days on which their paid chiropractic services totaled  
16 hours or more. However, 81 percent of the payments for this measure 
went to two chiropractors (see Table 5).  This raises questions regarding 
the quality of patient care and, perhaps, whether these services were even 
rendered by the chiropractor.  
Table 5: Chiropractors Who Received 81 Percent of the Payments for 
Days With 16 Hours or More of Chiropractic Services  
Location  Description  
Medicare paid a chiropractor for claims totaling 16 hours or more on 140 
days of 2013, during which this chiropractor billed for providing an average  
California  
of 65 chiropractic services per day.  Solely for these dates, Medicare paid 
this chiropractor $322,887.  
Medicare paid a chiropractor $302,729 for 115 days of providing 
Illinois   16 hours or more of chiropractic services.  On these dates, this 
chiropractor was paid for an average of 88 chiropractic services per day.  
Source:  OIG analysis of data from 2013 Part  B claims  for chiropractic services paid for by Medicare. 
 
 
25 CMS, Medicare Learning Network,  Medicare Physician Fee Schedule:  Payment 
System Fact Sheet Series, ICN 006814, December 2014.  Higher RVUs result in  higher 
Medicare payments.   
26 OIG,  Inappropriate Medicare Payments for Chiropractic  Services. OEI-07-07-00390, 
May 2009. 
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   10 
  Two percent of chiropractors were responsible for half 
of the questionable payments 
In 2013, 962 ofthe 45,490 chiropractors paid by Medicare received 
$38 million of the $76 million in questionable payments (see Figure 2). 
These 962 chiropractors (hereinafter, chiropractors with high questionable 
payments) received 9 percent ($43.6 million) of all Medicare payments for 
chiropractic services in 2013.  We identified 87 percent of their payments 
as questionable. 
Figure 2:  Number and Percentage of Chiropractors With 
and Without Questionable Payments in 2013* 
Chiropractors with 
questionable payments 
Chiropractors without  ( 6,229) 14% 
questionable payments 
( 38,299 ) 84%  ~ 
Chiropractors with high 
questionable payments 
( 962) 2% 
Source: OIG analysis of data from 2013 Part B claims for chiropractic services paid for by Medicare. 
* A total of 45,490 chiropractors were paid by Medicare in 2013. The total number of chiropractors with 
questionable payments in 2013 was 7, 191. 
Chiropractors with high questionable payments provided more 
services to more beneficiaries compared to all other 
chiropractors 
On average, chiropractors with high questionable payments provided 
chiropractic services to twice the number of beneficiaries compared to all 
other chiropractors (see Table 6).  In addition, the chiropractors with high 
questionable payments had about 4 times the number of paid chiropractic 
claims compared to all other chiropractors.  Accordingly, the Medicare 
payments to chiropractors with high questionable payments were also 
4 times higher than payments to other chiropractors. 
Questionable and Inappropriate Payments for Chiropractic Services (OEl-01-14-00200)  11   
   
Table 6: Payments to Chiropractors with High Questionable Payments 
Compared to All Other Chiropractors 
Chiropractors with High  All Other Chiropractors 
  Questionable Payments  (N=44,528)  
(N=962)  
Average paid amount per 
$45,313   $10,303  
chiropractor  
Average number of paid claims per 
1,604   407 
chiropractor  
Average number of beneficiaries per 
101  47 
chiropractor with paid services 
Source:  OIG analysis of data from 2013 Part  B claims  for chiropractic services paid for by Medicare. 
Half of these chiropractors questionable payments were for 
treatments suggestive of maintenance therapy 
In addition to being high-volume providers, chiropractors with high 
questionable payments had more payments for claims suggestive of 
maintenance therapy.  For the chiropractors with high questionable 
payments, 53 percent of their claims were suggestive of maintenance 
therapy. In contrast, just 3 percent of the claims  for all other chiropractors 
paid by Medicare in 2013 were suggestive of maintenance therapy.   
Over a quarter of these chiropractors claims were for the 
highest intensity chiropractic service  
Medicare paid the chiropractors with high questionable payments 
substantially more for treatments to five regions of the spine, CPT code 
98942. Twenty-eight percent of paid services provided by chiropractors 
with high questionable payments were for 98942.  In contrast, only 
5 percent of paid services provided by all other chiropractors were for this  
CPT code.  Finally, 30 percent of the chiropractors with high questionable 
payments received 95 percent or more of their Medicare payments for 
CPT code 98942, yet just 3 percent of all other chiropractors received 
95 percent or more of their Medicare payments for this code.   
Many chiropractors with high questionable payments 
shared certain characteristics 
Chiropractors with high questionable payments were located 
in certain States as well as in high-fraud areas 
Fifty-nine percent of the chiropractors with high questionable payments 
were concentrated in seven States:  California, Michigan, Illinois, 
New York, Kansas, Florida, and New Jersey.  Each of these States had 
more than 50 chiropractors with high questionable payments.  In total, 
these chiropractors received about a third ($23.8 million) of all 
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   12 
   
   
questionable payments in 2013.  The remaining 41 percent of 
chiropractors with high questionable payments were located in 38 other 
States.  
In addition, most of the counties that had 10 or more chiropractors with 
high questionable payments are located in Medicare Fraud Strike Force 
(Strike Force) areas (see Table 7).  The Strike Force operates in locations 
considered to be hot spots for Medicare fraud and targets suspicious 
billing patterns as well as emerging schemes that migrate from one 
community to another.27,28  The chiropractors in the 11 Strike Force 
counties included in Table 7 represented nearly one quarter of the 
chiropractors with high questionable payments, and they collectively 
received $9.5 million in questionable payments.  
Table 7: Counties with 10 or more Chiropractors With High Questionable Payments, 
Ordered by  Payment Total 
County and State  Number of   Questionable   Percent of  Strike 
Chiropractors  Payments to  Questionable   Force 
with High  Chiropractors with  Payments to  Area  
Questionable   High Questionable  Chiropractors with 
Payments   Payments   High Questionable 
Payments  
Queens County, New York   20  $1,571,702  4.1%   
 
Los Angeles County, California   24  $1,380,929  3.6%   
 
Cook County, Illinois  29  $1,377,090  3.6%   
 
Kings County, New  York   15  $992,092  2.6%   
 
Wayne County,  Michigan  26  $892,619  2.3%   
 
Maricopa County, Arizona  21  $726,743  1.9%    
Orange County, California  18  $710,418  1.9%   
 
Oakland County, Michigan  20  $596,077  1.6%   
 
Macomb County, Michigan  19  $577,878  1.5%   
 
Suffolk County, New York   15  $566,548  1.5%   
 
San Diego County, California   10  $502,971  1.3%    
Sedgwick County, Kansas    12  $478,794  1.3%    
Du Page County, Illinois   11  $444,362  1.2%   
 
Nassau County, New York   14  $370,266  1.0%   
 
Source:  OIG analysis of data from 2013 Part  B claims  for chiropractic services paid for by Medicare.  
 
27  As of August 2015, the Medicare Fraud Strike Force was operating in Brooklyn, 
Chicago, Dallas, Detroit,  Los  Angeles, Miami, southern Louisiana, southern Texas, and 
Tampa.  Also see http://www.hhs.gov/news/press/2014pres/02/20140226a.html. 
28 Department of Health and Human Services and Department of Justice, Health Care 
Fraud and Abuse Control Program  Annual  Report for Fiscal Year 2014. 
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   13 
   
   
Beneficiaries of chiropractors with high questionable 
payments were more likely to have paid claims for physical 
and occupational therapy on the same day, especially in 
high-fraud areas 
Thirteen percent of beneficiaries who had a paid claim for a service from a 
chiropractor with high questionable payments also had one or more paid 
claims for physical/occupational therapy (hereinafter, therapy services) on 
the same day.  In contrast, only 4 percent of beneficiaries who had services 
from other chiropractors had therapy services on the same day.  Moreover,  
beneficiaries with paid claims from a chiropractor with high questionable 
payments had an average of three times the dollar amount of therapy 
services on the same day than the other beneficiaries (see Table 8). 
 
Table 8: Physical and Occupational Therapy Services That Were Provided on the Same 
Day as Chiropractic Services  
Beneficiaries with Same-Day   Total Paid  Average Payment  Average Number   Average 
Chiropractic and Therapy Services  Amount for  per Beneficiary  for  of Therapy  Claims  Payment per 
Therapy   Therapy Services  per Beneficiary   Therapist  
Services 
Beneficiaries with paid claims from  $10,618,801   $982   34  $4,680  
chiropractors with high questionable 
payments  
Beneficiaries with no paid claims  $22,177,479  $320   11  $930  
from chiropractors with high 
questionable payments 
Source:  OIG analysis of data from 2013 Part  B claims  for physical and occupational  services paid for by Medicare.  
Although it is plausible that some beneficiaries had same-day therapy 
independent of the chiropractic services, the concentration of providers of 
both types of servicesas well as their locations and amount of therapy 
services providedsuggests otherwise.  Sixty percent of chiropractors 
with high questionable payments had two or more beneficiaries who 
received same-day therapy services. In contrast, just 24 percent of 
chiropractors without high questionable payments had two or more 
beneficiaries who received same-day therapy services.  In addition, the 
payments to therapists appear to be concentrated in amount and location.  
The average payment to therapists for beneficiaries who received same-
day services from chiropractors with high questionable payments was five 
times higher than the average payment to therapists for other beneficiaries.  
Moreover, 90 percent of the $10.6 million in payments for same-day 
therapy services was paid to therapists in Strike Force areas, and Medicare 
paid just over half of this amount to only 16 therapists.  
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   14 
  Most chiropractors with high questionable payments in 2013 
also had questionable payments in a prior year 
The chiropractors with high questionable payments also received a total of 
nearly $100 million in questionable payments from 2009-2012 (see 
Figure 3).  In addition, almost half of the chiropractors with high 
questionable payments in 2013 had at least one questionable payment in 
each year between 2009 and 2012, thus demonstrating that these 
chiropractors had a consistent pattern of questionable payments over a 
5-year span. 
Figure 3:  Percentage of Chiropractors With High Questionable 
Payments in 2013 (N=962) Who Had Questionable Payments in 
2009-2012 
100%  $35 
Cf) 
$30  c 
90% 
$30  .Q 
80% 
$23  ~ 
70%  $25 
$20  d 
60%  J.a 
$20 
50% 
$15 
40%  80% 
70% 
30%  57%  61%  $10 
20% 
$5 
10% 
0%  $0 
2009  2010  2011  2012 
Percentage of chiropractors with questionable payments 
- Amount of questionable payments 
Source: OIG analysis of data from Part B claims from 2009-2012 for chiropractic services paid for by Medicare. 
In 2013, Medicare inappropriately paid $21  million for 
chiropractic services lacking a covered primary 
diagnosis 
Thirty-nine percent of chiropractors received a total of $20.7 million for 
claims that lacked a covered primary diagnosis code (see Table 9);29  We 
used CMS 's guidance and MACs' local coverage determinations to 
identify claims that lacked a primary diagnosis covered by Medicare.  All 
29 Some of these inappropriate claims (126,873 claims totaling $3.6 million) were also 
identified as questionable payments for other reasons, based on our four measures.  See 
Table B4 in Appendix B for a detailed breakdown of questionable and inappropriate 
chiropractic claims in 2013 . 
Questionable and Inappropriate Payments for Chiropractic Services (OEl-01 -14-00200)  15   
   
MACs but one have local coverage determinations that align with CMSs 
guidance. That one MAC has a local coverage determination allowing 
coverage of chiropractic services for 209 primary diagnoses, but it does 
not include the diagnosis codes for nonallopathic lesions.  As a result, we 
did not count the payments for claims with these 209 primary diagnoses in 
this MACs jurisdiction as inappropriate.30    
The other two measures of inappropriate payment that we analyzed 
claims for duplicate services and claims lacking the AT modifier 
identified only about a thousand claims that totaled $27,259. 
 
Table 9: Chiropractors and Paid Amount by Measure of Inappropriate Payment in 2013* 
Number of   Percentage of   Paid  Percentage of  
Measure of Inappropriate Payment  
Chiropractors   Chiropractors   Amount  Paid Amount 
Claims lacking a covered primary diagnosis  17,640   38.8%   $20,709,516   4.1%  
Claims for duplicate services  225  Less than 1%   $25,680  Less than 1%  
Claims lacking the AT modifier   30  Less than 1%   $1,579   Less than 1%  
Total   17,751   39.0%   $20,735,315   4.1%  
Source:  OIG analysis of data from 2013 Part  B claims  for chiropractic services paid for by Medicare. 
* Because some claims exceeded the threshold for more than one  measure of inappropriate payment, the columns do not sum to the totals.   
 
   
 
30 CMS, Local Coverage Determinations L29099  and L29114 for Chiropractic Services. 
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   16 
   
   
CONCLUSION AND RECOMMENDATIONS 
Previous OIG work and the CERT identified questionable and 
inappropriate payments for chiropractic services as a longstanding 
concern. In this study, we used four measures to identify Medicare 
payments to chiropractors with billing characteristics that raise program  
integrity concerns, as well as payments for claims that did not meet certain  
Medicare rules for payment. We found that in 2013, nearly 20 percent of 
the payments for chiropractic services were questionable or inappropriate, 
based on these measures and selected requirements.  
Especially concerning is that just 2 percent of chiropractors paid by 
Medicare in 2013 received half of the questionable payments.  Many of 
these 962 chiropractors had a history of receiving questionable payments 
in prior years and/or were located in high-fraud areas.  Although this study 
did not determine whether the questionable payments we identified for 
chiropractic services were fraudulent or improper, the concentration of 
payments to these 962 chiropractors suggests that further scrutiny of them  
and their payments is warranted. 
In addition, over half of the questionable payments we identified were for 
treatment suggestive of maintenance therapy, and almost all of the 
inappropriate payments that we identified were for claims lacking a 
covered primary diagnosis.  CMS instituted the AT modifier as a control to 
prevent Medicare from paying for maintenance therapy.  However, the 
evidence in this study, as well as previous OIG work, shows that the AT  
modifier is not an effective safeguard.  In addition, the payments for 
services with primary diagnoses other than subluxation indicate that 
Medicare paid for chiropractic services that did not meet coverage 
requirements. 
The Medicare Access and CHIP Reauthorization Act of 2015 (MACRA), 
which became law in April 2015, contains provisions for oversight of 
Medicare chiropractic services, including requiring preauthorization for 
services provided by chiropractors with aberrant billing or high rates of 
denial.31   Through targeted tactics that align with or complement these new 
provisions, CMS can address the vulnerabilities that we identify in this 
study. 
   
 
31 P.L. No. 114-10, Title V, Subtitle A,   514  (April 16, 2015). 
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   17 
   
   
We recommend that CMS: 
Establish a more reliable control for identifying active 
treatment 
Given that half of the questionable payments that we identified in 2013 
were for treatment suggestive of maintenance therapy, CMS should devise 
a more reliable method for detecting it.  As a first step, CMS could 
examine the date of initiation of treatment for a particular diagnosis 
reported on a chiropractic claim.  Doing so would enable CMS to 
determine the length of a beneficiarys chiropractic treatment and identify  
treatments likely to be maintenance therapy.  CMS could also consider 
including this information in the National Claims History file so that it is 
available to Medicare contractors for pre- and post-payment review. 
Develop and use measures to identify questionable payments 
for chiropractic services 
CMS could use these measures in a variety of ways.  For example, it could 
use measures as part of its Fraud Prevention System to identify 
chiropractors for investigatory followup.  It also could use measures to 
help its contractors identify and review potentially upcoded claims.  In 
addition, it could use measures to identify and examine same-day services 
(such as therapy services) provided to beneficiaries, especially in 
high-fraud areas. Lastly, it could use measures to identify chiropractors 
who warrant pre- or post-payment review of services as called for in 
MACRA.  
Take appropriate action on the chiropractors with questionable 
payments  
We identified 7,191 chiropractors with questionably paid claims, 962 of 
whom received half of the questionable payments.  In a separate 
memorandum, we will provide CMS with information on chiropractors 
with high questionable payments, so that it may take action.  CMS and/or 
its contractors should review their claims and take appropriate action.  
Such actions could include: (1) recouping inappropriate payments; 
(2) educating providers on proper billing; (3) making referrals to law 
enforcement; (4) imposing payment suspensions; (5) revoking billing 
privileges; or (6) taking no action, if the payment is determined to be 
appropriate. 
Collect overpayments based on  inappropriately paid claims 
CMS should collect the $20.7 million in payments that resulted from the 
inappropriate claims we identified.  In a separate memorandum, we will 
refer these claims to CMS for collection.  
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   18 
   
   
Ensure that claims are paid only for Medicare-covered 
diagnoses 
Although Medicare requires a diagnosis of subluxation of the spine, no 
diagnosis code exists with that description.  CMS should work with MACs 
to ensure that claims are paid for diagnosis codes that meet current and 
future Medicare coverage requirements.  This would be a timely action to 
take, given that new diagnosis codes for subluxation will be used when 
ICD-10 is implemented in October 2015.32  In addition, CMS should 
assess whether the diagnosis codes that its MACs use in their local 
coverage determinations are consistent with national Medicare coverage 
policy. 
   
 
32 The ICD (International Classification  of Diseases) is an international diagnostic tool  
that provides a system of diagnostic codes.  
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   19 
   
   
AGENCY COMMENTS AND OFFICE OF INSPECTOR GENERAL  
RESPONSE 
CMS did not concur with our first recommendation and concurred with 
our other four recommendations. 
CMS did not concur with our recommendation to establish a more reliable 
control for identifying active treatment, citing significant obstacles to 
doing so. CMS stated that it will implement prior authorization medical 
review required by MACRA, which it believes will help address the 
concerns we identified. However, we are uncertain that this adequately 
addresses our concerns with payments for maintenance therapy.  The 
medical review under MACRA targets a narrow group of chiropractors 
with aberrant billing or high rates of claim denial, who are not necessarily 
chiropractors receiving payments for maintenance therapy.  
CMS concurred with our recommendation to develop and use measures to 
identify questionable payments for chiropractic services.  CMS stated that 
it will reexamine its models for identifying chiropractic fraud, waste, and 
abuse and that it will look for opportunities to improve or extend these 
models. 
CMS concurred with our recommendation to take appropriate action on 
the chiropractors with questionable payments.  CMS stated that it will 
consider chiropractors we identified when it develops postpayment review 
under MACRA. However, postpayment review will apply to chiropractic 
services provided on or after January 1, 2017. CMSs approach may delay 
appropriate action on chiropractors we identified as having high 
questionable payments, many of whom were paid millions of dollars for 
questionable claims for several years.  In the near term, we urge CMS to 
consider the approaches that we suggest in our recommendation and 
determine the appropriate course of action.   
CMS concurred with our recommendation to collect overpayments for 
inappropriately paid claims.  CMS stated that it will analyze the claims we 
provide, determine which to review more closely, and take appropriate 
action as needed. We are forwarding to CMS by separate memorandum  
the claims that we have already identified as not meeting Medicares 
coverage requirements to facilitate overpayment recovery. 
CMS concurred with our recommendation to ensure that claims are paid 
only for Medicare-covered diagnoses. CMS stated it will work with the 
MACs to ensure that claims are paid only for the diagnosis codes that 
meet Medicare coverage requirements. 
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   20 
   
   
We ask that CMS provide details on its efforts to address our 
recommendations in its final management decision.  For the full text of 
CMSs comments, see Appendix C.   
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   21 
   
   
APPENDIX A 
Detailed Methodology 
Data Collection and Analysis 
This study is primarily based on our analysis of national Medicare Part B 
claims for chiropractic services from 2013.  To create our data set of 
chiropractic claims, we identified all claims from CMSs National Claims  
History Carrier File for chiropractic services (CPT codes 98940, 98941, 
 
and 98942) rendered in 2013 with a paid amount greater than $0.33  This 
resulted in 19,671,262 claims for which 45,490 providers received 
payment.  Although providers other than chiropractors are able to bill and  
be paid for chiropractic services, over 99 percent of paid claims in 2013 
for chiropractic services were furnished by chiropractors.  For this reason, 
we collectively refer to providers of chiropractic services as chiropractors 
in this report. 
Identification of Inappropriately Paid Claims 
We define inappropriately paid claims as those that did not meet the 
Medicare requirements for payment.  We developed three measures of 
inappropriate payment and analyzed the data set of all paid claims to 
determine the extent to which Medicare inappropriately paid claims based 
on the following criteria. 
The three measures of inappropriate payment are as follows: 
1.	   Claims lacking a covered primary diagnosis. Medicare requires a 
primary diagnosis of subluxation on claims for chiropractic 
services. Although no diagnosis code exists that contains the word 
subluxation, CMS has instructed chiropractors to use ICD-9 codes 
in the 739 series, which indicate nonallopathic lesions of the 
spine.34   All but one of the MACs local coverage determinations  
for chiropractic services require a diagnosis code in the 739 series 
as the primary diagnosis.  The local coverage determination for the 
remaining MAC, which handles claims for services provided in 
Florida, Puerto Rico, and the Virgin Islands, lists 209 diagnosis 
codes that can be used for the primary diagnosis on chiropractic 
claims but does not list the diagnosis codes in the 739 series among 
these.35    
 
33 Because of sequestration, Medicare fee-for-service claims  with dates of service on or 

after April 1, 2013 incurred a 2  percent reduction in payment.  See CMS, Mandatory 
 
Payment Reductions in the Medicare Fee-for-Service (FFS) ProgramSequestration, 
 
March 8,  2013. 

34 CMS, Medicare Learning Network,  Chiropractic Services, ICN 906143 October 2013. 

35 CMS, Local Coverage Determinations L29099 and L29114  for chiropractic services. 
 
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   22 
   
   
Thus, for chiropractic services provided in all States, we counted 
any claim with a primary diagnosis code in the 739 series as 
appropriate because those claims were in accordance with CMSs 
instructions to chiropractors. For chiropractic services provided in 
Florida, Puerto Rico, and the Virgin Islands, we also counted any 
claim with a primary diagnosis code listed in the local coverage 
determination as appropriate. 
2. 	  Duplicate services.  These are paid claims for chiropractic 
treatments provided on the same day for the same beneficiary with 
the same diagnosis and procedure codes and the same chiropractor.  
In any instance where there were two or more claims with this 
same information, we counted all of the duplicate claims as 
inappropriate. 
3. 	  Claims lacking the AT modifier. CMS requires that chiropractic 
claims include the AT modifier, which indicates active treatment 
and is required for payment. We counted any paid claim that 
lacked this modifier as inappropriate. 
Identification of Questionably Paid Claims 
Population  For our analysis of questionably paid claims, we used the 
aforementioned data set of claims for chiropractic services with some  
exclusions. 
	   Claims for services submitted by beneficiaries that lacked the 
providers National Provider Identifier (NPI) or contained an NPI 
that lacked the proper number of digits.  
	   Claims from chiropractors that had fewer than 10 paid claims or 
paid claims for just 1 beneficiary.    
Based on these two criteria, we excluded 4.8 percent of chiropractors and 
0.1 percent of both claims and the paid amount for our questionable 
payment analyses.  Table A1 provides the totals before and after the 
exclusions.  
  Table A1:  Totals for Chiropractors, Claims, and Paid Amount Excluded 

  from Questionable Payment Analysis 

Data Set  Chiropractor NPIs  Claims   Paid Amount 
Before exclusions  45,490   19,671,262   $502,356,538  
Exclusions made  2,206   20,093   $495,380  
Totals after exclusions   43,284   19,651,169   $501,861,158  
Source:  OIG analysis of data from 2013 Part  B claims  for chiropractic services paid for by Medicare.  
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   23 
   
   
Measures of questionable payment - We developed four measures of 
questionable payment based on previous OIG reports, fraud investigations 
of chiropractic services, interviews with experts in chiropractic practice 
and fraud detection, and our own analysis.  For the first, second, and third 
measures we used a statistical technique called the Tukey method to 
identify chiropractors who were outliers on these measures compared to 
other chiropractors.  For these measures, we considered a chiropractors 
payments to be unusually high, or questionable, if the payments were 
 
greater than the 75th percentile plus 1.5 times the interquartile range.36  
For the fourth measure, we used our knowledge and experience to 
establish a threshold to identify chiropractors with questionable payments. 
The four questionable payment measures are as follows: 
1. 	  Treatment suggestive of maintenance therapy. A high average 
number of claims per beneficiary per chiropractor suggests the 
services provided were for active treatment.  To calculate this 
measure, for each chiropractor we determined the average number 
of paid claims per beneficiary.  Using the Tukey method, we 
determined that 20 services per beneficiary was the threshold for 
this measure.   We identified as an outlier any chiropractor whose 
average number of paid claims per beneficiary exceeded the 
threshold.  For these chiropractors, we identified their 
beneficiaries who had treatments in excess of the threshold and 
considered all claims associated with these beneficiaries to be 
questionable. Although a beneficiary could legitimately receive a 
high number of chiropractic services in a year (e.g., because of  
different diagnoses), this measure identifies chiropractors who 
provide a high average number of services across all their 
beneficiaries. 
2. 	  Potential sharing of beneficiaries. A high percentage of a 
chiropractors beneficiaries who received services from another 
chiropractor suggests misuse of beneficiary identification 
numbers.  To calculate this measure, for each chiropractor we  
determined the percentage of her/his beneficiaries who had paid 
services from two or more chiropractors.  Using the Tukey 
method, we identified the threshold as 52.5 percent of a 
chiropractors beneficiaries who received services from another 
 
36 This is a standard exploratory method for identifying members of a population  with  
unusually high values  on a given statistic compared to the rest of the population when  no  
established benchmarks exist.  See J.W. Tukey,  Exploratory Data  Analysis, 
Addison-Wesley, 1977. The interquartile range is the value at the 75th percentile minus  
the value at the 25th  percentile. 
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   24 
   
   
chiropractor.  For chiropractors whose percentage exceeded the 
threshold, we considered all of their payments for the 
beneficiaries seen by other chiropractors to be questionable. 
3.	   Potentially upcoded claims. A high average level of services for 
a chiropractors claims suggests billing for services at a higher 
level than warranted.  To calculate this measure, we first used  
CMSs 2013 National Physician Fee Schedule Relative Value File 
to identify the work relative value units (RVUs) for each of the 
three chiropractic CPT codes covered by Medicare.  Based on this 
file, we counted CPT code 98940 as 0.45 work RVUs, CPT code 
98941 as 0.65 work RVUs, and CPT code 98942 as 0.87 work 
RVUs.  We then calculated the average work RVUs for each 
chiropractors claims.  Using the Tukey method, we determined 
that 0.85 was the threshold for this measure.  For the 
chiropractors that had average work RVUs greater than the 
threshold, we considered all of their claims for CPT code 98942 
to be questionable. 
4.	   Unlikely number of services per day. A high number of hours of 
services provided on 1 day by a chiropractor suggests billing for 
services of diminished quality and for services that were not 
rendered. To calculate this measure, we first determined the 
length of time for chiropractic services based on the total time for 
each CPT code in CMSs 2013 Time File from the Physician Fee 
Schedule. Based on this file, we counted CPT code 98940 as 
12 minutes, CPT code 98941 as 17 minutes, and CPT code 98942 
as 21 minutes.  We then calculated the number of hours per day 
for each chiropractors paid services.   We established 16 hours as 
the threshold for this measure.  We considered all of a 
chiropractors claims on any day that met or exceeded the 
threshold as questionable. 
See Tables B1 and B2 in Appendix B for threshold data and number of 
questionable claims for each questionable measure. 
Identification and Description of Chiropractors with High 
Questionable Billing 
After identifying the chiropractors who had questionable payments, we 
determined the number of them who received half of all questionable 
payments.  We refer to these chiropractors as chiropractors with high 
questionable payments.   
Provider location/Strike Force area. We used the ZIP Code for the 
chiropractor that was included in the National Claims History Carrier File 
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   25 
   
   
to identify the State and county in which each chiropractor was located.  
We then consulted with our Office of Investigations to determine whether 
the counties were located in Medicare Fraud Strike Force areas.   
Questionable payments in prior years. To determine the extent to which  
the chiropractors with high questionable payments received similar 
questionable payments in prior years, we analyzed data from 20092012.  
We used the same measures to identify questionable payments in 2013 to 
determine how many of the chiropractors with high questionable payments 
in 2013 had received questionable payments in the prior years and the 
amount of questionable payments that Medicare paid these chiropractors 
for the measures of questionable payment. 
Analysis of same-day physical and occupational therapy services. For 
each beneficiary who received a Medicare-paid chiropractic service in 
2013, we identified the date of that service and whether the beneficiary 
received the service from one of the chiropractors with high questionable 
payments.  Next, from CMSs National Claims History Carrier File, we 
obtained the paid claims with the CPT codes for 32 selected physical and 
occupational therapy services (hereinafter, therapy services) that occurred 
on the same day as the beneficiaries  chiropractic services.  We calculated 
the overall paid amount of therapy services and the average number of 
therapy services per beneficiary.   We calculated these amounts separately 
for the beneficiaries who had same-day chiropractic services with the 
chiropractors with the high questionable payments and for beneficiaries 
who did not have same-day services with these chiropractors.  We  
compared the Medicare payments for these beneficiaries therapy services  
to the Medicare payments for the therapy services received by all other 
beneficiaries who received chiropractic services in 2013. 
Limitations 
We did not conduct a medical record review to determine whether 
chiropractic services were medically necessary or had been coded 
correctly.  The measures included in our analysis are not intended to be a 
comprehensive set of characteristics for identifying chiropractors with 
questionable and inappropriate payments.  Moreover, the four measures 
that identify questionable payments used in this study do not provide 
conclusive evidence of improper or fraudulent payments.  Rather, the 
measures are intended to identify Medicare payments to chiropractors that 
exceed those of other chiropractors in ways that raise program integrity 
concerns. Further investigation would be required to determine whether 
these chiropractors were paid for improper or fraudulent Medicare claims  
for chiropractic services. 
   
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   26 
   
   
APPENDIX B 
Summary Data for Questionable and Inappropriate Payments 
 
Table B1:  Threshold and Summary  Data for Each Measure of Questionable Payment in 
2013  
Summary Statistics for All Chiropractors With  
Measure of   Threshold for Chiropractor To  Paid Claims  
Questionable Payment   Be Considered  an Outlier  
Median  Minimum  Maximum 
Average of 8  Average of 1  Average of 160 
Treatment Suggestive of   Was paid for an average of 20 
services per  service per  services per 
Maintenance Therapy  services per beneficiary 
beneficiary   beneficiary   beneficiary  
52.5% of a chiropractors 
Potential Sharing of  13% of  0% of  100% of 
beneficiaries had paid claims 
Beneficiaries  beneficiaries  beneficiaries  beneficiaries 
from another chiropractor  
Was paid for an average of 0.85  
Potentially Upcoded  Average of 0.63  Average of 0.45  Average of 0.87 
work relative value units (RVU) 
Claims  work RVU   work RVU   work RVU  
per service 
Unlikely Number of  Was paid for 16 or more hours in  0.57 hours in  0.20 hours in  28.62 hours in 
Services per Day  1 day   1 day  1 day  1 day 
Source:  OIG analysis of data from 2013 Part  B claims  for chiropractic services paid by Medicare.  
 
 
 
Table B2:  Chiropractic Claims by Measure of Questionable Payment in 2013*  
Percentage of Total  
Measure of  Questionable Payment   Number of Claims  
Paid Claims  
Treatment Suggestive of Maintenance Therapy   1,271,815   6.5%  
Potential Sharing of Beneficiaries  988,926   5.0%  
Potentially Upcoded Claims  603,655   3.1%  
Unlikely Number of Services per Day  24,465   0.1%  
Total   2,719,427   13.8%  
Source:  OIG analysis of data from 2013 Part  B claims  for chiropractic services paid by Medicare.  
* Because some claims exceeded the threshold for more than one measure of questionable payment, the columns do not sum to the 
totals.   
 
 
 
 
 
 
 
 
 
 
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   27 
   
   
Table B3:  Chiropractic Claims by Measure of Inappropriate Payment in 2013*  
Percentage of Total  
Measure of Inappropriate Payment   Number of Claims  
Paid Claims  
Claims lacking a covered primary diagnosis  808,971   4.1%  
Claims for duplicate services (i.e., services provided on the 
same day for the same beneficiary with the same diagnosis and  970  Less than 1%  
procedure codes and the same chiropractor)  
Claims lacking the AT modifier   61  Less than 1%  
Total   809,945   4.1%  
Source:  OIG analysis of data from 2013 Part  B claims  for chiropractic services paid by Medicare. 
* Because some claims exceeded the threshold for more than one measure of questionable payment, the columns do not sum to the 
totals.   
 
 
Table B4:  Totals for Questionably and Inappropriately Paid  Claims for Chiropractic 
Services in 2013  
Number of   Percentage of Paid 
  Paid Amount*  
Claims   Amount* 
Questionably paid  2,592,554   $72,507,606   14.4%  
Inappropriately paid  683,072   $17,138,222   3.4%  
Both questionably and inappropriately paid   126,873   $3,597,093   0.7%  
Neither inappropriately nor questionably paid   16,268,763   $409,113,618   81.4%  
Total   19,671,262   $502,356,538   100%  
Source:  OIG analysis of data from 2013 Part  B claims  for chiropractic services paid by Medicare. 
* The amounts in these columns do not sum to  the total because of rounding. 
 
 
   
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APPENDIX C 
Agency Comments 
 
 
   
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Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)  30 
   
   
 
   
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)  31 
   
   
ACKNOWLEDGMENTS 
This report was prepared under the direction of Joyce Greenleaf, Regional 
Inspector General for Evaluation and Inspections in the Boston regional 
office, and Russell Hereford and Kenneth Price, Deputy Regional 
Inspectors General.  
Maria Maddaloni served as the team leader for this study, and 
Kimberly Ruppert served as the lead analyst.  Central office staff who 
provided support include Mandy Brooks, Berivan Demir Neubert, 
Evan Godfrey, Dave Graf, Althea Hosein, Scott Manley, and 
Christine Moritz.  
Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200)   32 
   
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