Suzanne Murrin 

Deputy Inspector General 

for Evaluation and Inspections 

 

September 2015 

OEI-01-14-00200 

Department of Health and Human Services 

OFFICE OF 

INSPECTOR GENERAL 

CMS SHOULD USE 

TARGETED TACTICS TO CURB 

QUESTIONABLE AND 

INAPPROPRIATE PAYMENTS FOR 

CHIROPRACTIC SERVICES 
 

 

 

 

 

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/pressreleases/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-chiropractorsentenced-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, 2010–2014 

Year 

Amount of Projected 

Improper Payments for 

Chiropractic Services 

Rate of Improper 

Payments for 

Chiropractic Services 

Rate of Improper 

Payments 

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 2010–2014. 

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 2010–2014. 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 

98940 Treatment of one to two 

spinal regions 

98941 Treatment of three to four 

spinal regions 

98942 Treatment of five spinal 

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 chiropractor’s 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 

chiropractor’s 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 chiropractor’s 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 CMS’s 

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 lo cations using the ZIP Codes on their 

claims. We identified past questionable payments by analyzing 

chiropractic claims data from 2009–2012 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* 

Measure of Questionable Payment Paid Amount 

for Measure* 

Percentage 

of Total 

Paid 

Amount 

Number of 

Chiropractors* 

Percentage of 

Chiropractors 

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 beneficiary’s 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 CMS’s 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 

California 

Ninety-nine percent of a chiropractor’s payments were for claims suggestive of 

maintenance therapy. Several beneficiaries of this chiropractor each had more than 

250 visits in 2013. 

Missouri All but one of the beneficiaries seen by a chiropractor in 2013 each had more than 

20 visits. These beneficiaries had an average of 172 visits with this chiropractor. 

New York Medicare paid a chiropractor over $205,000 for about 200 beneficiaries who had 

treatments suggestive of maintenance therapy in 2013. 

Michigan Almost two-thirds of a chiropractor’s beneficiaries had treatment suggestive of 

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 CMS’s 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.
 

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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 code—98942— 

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 

California 

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 

of 65 chiropractic services per day. Solely for these dates, Medicare paid 

this chiropractor $322,887. 

Illinois 

Medicare paid a chiropractor $302,729 for 115 days of providing 

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 
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% 

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. 

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. 

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Table 6: Payments to Chiropractors with High Questionable Payments 

Compared to All Other Chiropractors 

Chiropractors with High 

Questionable Payments 

(N=962) 

All Other Chiropractors 

(N=44,528) 

Average paid amount per 

chiropractor $45,313 $10,303 

Average number of paid claims per 

chiropractor 1,604 407 

Average number of beneficiaries per 

chiropractor with paid services 101 47 

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 

Chiropractors 

with High 

Questionable 

Payments 

Questionable 

Payments to 

Chiropractors with 

High Questionable 

Payments 

Percent of 

Questionable 

Payments to 

Chiropractors with 

High Questionable 

Payments 

Strike 

Force 

Area 

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 

Chiropractic and Therapy Services 

Total Paid 

Amount for 

Therapy 

Services 

Average Payment 

per Beneficiary for 

Therapy Services 

Average Number 

of Therapy Claims 

per Beneficiary 

Average 

Payment per 

Therapist 

Beneficiaries with paid claims from 

chiropractors with high questionable 

payments 

$10,618,801 $982 34 $4,680 

Beneficiaries with no paid claims 

from chiropractors with high 

questionable payments 

$22,177,479 $320 11 $930 

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 services—as well as their locations and amount of therapy 

services provided—suggests 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 sameday 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 
Figure 3: Percentage of Chiropractors With High Questionable 

Payments in 2013 (N=962) Who Had Questionable Payments in 

2009-2012 

100% $35 Cf) 

90% $30 

$30 

c 

.Q 

80% ~ 

70% 

$20 

$23 

d $25 

60% J.a $20 

50% 

40% 80% $15 

70% 

30% 61% $10 

20% 

57% 

$5 10% 

0% $0 

2009 2010 2011 2012 

Percentage of chiropractors with questionable payments 

- Amount of questionable payments 

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. 

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 CMS’s 

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 MAC’s 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* 

Measure of Inappropriate Payment Number of 

Chiropractors 

Percentage of 

Chiropractors 

Paid 

Amount 

Percentage of 

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 beneficiary’s 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 
 

 

Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200) 19 

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. 
 

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. CMS’s 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 Medicare’s 

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 

CMS’s 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 CMS’s 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) Program—“Sequestration,”
 

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 CMS’s 

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 

provider’s 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 chiropractor’s 

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 

chiropractor’s 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 

chiropractor’s 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 chiropractor’s claims suggests billing for services at a higher 

level than warranted. To calculate this measure, we first used 

CMS’s 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 

chiropractor’s 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 CMS’s 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 chiropractor’s paid services. We established 16 hours as 

the threshold for this measure. We considered all of a 

chiropractor’s 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 2009–2012. 

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 CMS’s 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 

Tabl

2013

e B1: Threshold and Summary Data for Each Measure of Questionable Payment in 

Measure of 

Questionable Payment 

Threshold for Chiropractor To 

Be Considered an Outlier 

Summary Statistics for All Chiropractors With 

Paid Claims 

Median Minimum Maximum 

Treatment Suggestive of 

Maintenance Therapy 

 Was paid for an average of 20 

services per beneficiary 

Average of 8 

services per 

beneficiary 

Average of 1 

service per 

beneficiary 

Average of 160 

services per 

beneficiary 

Potential Sharing of 

Beneficiaries 

52.5% of a chiropractor’s 

beneficiaries had paid claims 

from another chiropractor 

13% of 

beneficiaries 

0% of 

beneficiaries 

100% of 

beneficiaries 

Potentially Upcoded 

Claims 

Was paid for an average of 0.85 

work relative value units (RVU) 

per service 

Average of 0.63 

work RVU 

Average of 0.45 

work RVU 

Average of 0.87 

work RVU 

Unlikely Number of 

Services per Day 

Was paid for 16 or more hours in 

1 day 

0.57 hours in 

1 day 

0.20 hours in 

1 day 

28.62 hours in 

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* 

Measure of Questionable Payment Number of Claims Percentage of Total 

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* 

Measure of Inappropriate Payment Number of Claims Percentage of Total 

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 

procedure codes and the same chiropractor) 

970 Less than 1% 

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 

Claims Paid Amount* Percentage of Paid 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. 

Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200) 28 
 

 

APPENDIX C 

Agency Comments 

Questionable and Inappropriate Payments for Chiropractic Services (OEI-01-14-00200) 29 
 

 

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 
Office of Inspector General

http://oig.hhs.gov 

The mission of the Office of Inspector General (OIG), as mandated by Public Law 95452, as 

amended, is to protect the integrity of the Department of Health and Human Services 

(HHS) programs, as well as the health and welfare of individuals served by those programs. 

This statutory mission is carried out through a nationwide network of audits, investigations, 

and inspections conducted by the following operating components: 

Office of Audit Services 

The Office of Audit Services (OAS) provides auditing services for HHS, either by conducting 

audits with its own audit resources or by overseeing audit work done by others. Audits 

examine the performance of HHS programs and/or its grantees and contractors in carrying 

out their respective responsibilities and are intended to provide independent assessments of 

HHS programs and operations. These assessments help reduce waste, abuse, and 

mismanagement and promote economy and efficiency throughout HHS. 

Office of Evaluation and Inspections 

The Office of Evaluation and Inspections (OEI) conducts national evaluations to provide 

HHS, Congress, and the public with timely, useful, and reliable information on significant 

issues. These evaluations focus on preventing fraud, waste, or abuse and promoting 

economy, efficiency, and effectiveness of departmental programs. To promote impact, OEI 

reports also present practical recommendations for improving program operations. 

Office of Investigations 

The Office of Investigations (OI) conducts criminal, civil, and administrative investigations 

of fraud and misconduct related to HHS programs, operations, and individuals. With 

investigators working in all 50 States and the District of Columbia, OI utilizes its resources 

by actively coordinating with the Department of Justice and other Federal, State, and local 

law enforcement authorities. The investigative efforts of OI often lead to criminal 

convictions, administrative sanctions, and/or civil monetary penalties. 

Office of Counsel to the Inspector General 

The Office of Counsel to the Inspector General (OCIG) provides general legal services to 

OIG, rendering advice and opinions on HHS programs and operations and providing all 

legal support for OIG’s internal operations. OCIG represents OIG in all civil and 

administrative fraud and abuse cases involving HHS programs, including False Claims Act, 

program exclusion, and civil monetary penalty cases. In connection with these cases, OCIG 

also negotiates and monitors corporate integrity agreements. OCIG renders advisory 

opinions, issues compliance program guidance, publishes fraud alerts, and provides other 

guidance to the health care industry concerning the anti-kickback statute and other OIG 

enforcement authorities.