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The American Journal of Managed Care August 2019
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Access to Chiropractic Care and the Cost of Spine Conditions Among Older Adults
Matthew A. Davis, PhD, DC, MPH; Olga Yakusheva, PhD; Haiyin Liu, MA; Joshua Tootoo, MS; Marita G. Titler, PhD, RN; and Julie P.W. Bynum, MD, MPH
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Access to Chiropractic Care and the Cost of Spine Conditions Among Older Adults

Matthew A. Davis, PhD, DC, MPH; Olga Yakusheva, PhD; Haiyin Liu, MA; Joshua Tootoo, MS; Marita G. Titler, PhD, RN; and Julie P.W. Bynum, MD, MPH
Among older adults who have a spine condition, access to chiropractic care may reduce medical spending on diagnostic services.

Objectives: Chiropractic care is a service that operates outside of the conventional medical system and is reimbursed by Medicare. Our objective was to examine the extent to which accessibility of chiropractic care affects spending on medical spine care among Medicare beneficiaries.

Study Design: Retrospective cohort study that used beneficiary relocation as a quasi-experiment.

Methods: We used a combination of national data on provider location and Medicare claims to perform a quasi-experimental study to examine the effect of chiropractic care accessibility on healthcare spending. We identified 84,679 older adults enrolled in Medicare with a spine condition who relocated once between 2010 and 2014. For each year, we measured accessibility using the variable-distance enhanced 2-step floating catchment area method. Using data for the years before and after relocation, we estimated the effect of moving to an area of lower or higher chiropractic accessibility on spine-related spending adjusted for access to medical physicians.

Results: There are approximately 45,000 active chiropractors in the United States, and local accessibility varies considerably. A negative dose–response relationship was observed for spine-related spending on medical evaluation and management as well as diagnostic imaging and testing (mean differences, $20 and $40, respectively, among those exposed to increasingly higher chiropractic accessibility; P <.05 for both). Associations with other types of spine-related spending were not significant.

Conclusions: Among older adults, access to chiropractic care may reduce medical spending on services for spine conditions.

Am J Manag Care. 2019;25(8):e230-e236
Takeaway Points
  • Chiropractic care is a Medicare-reimbursed service that operates outside of the conventional medical system and provides a sizable amount of the nation’s spine care.
  • Medicare beneficiaries can use chiropractic care without a medical referral.
  • Previous studies have not considered how use of chiropractic care affects spending on costly medical services.
  • We found some evidence of a relationship between lower accessibility of chiropractic care and higher spending on diagnostic imaging and testing for spine conditions.
Back pain and neck pain are associated with an estimated direct cost of $86 billion to the United States economy.1 Among the top contributors to disability, back pain and neck pain outrank chronic diseases such as chronic pulmonary disease, ischemic heart disease, and diabetes.2 Although back pain can be attributed to a serious underlying medical problem, up to 85% of cases are classified as nonspecific (ie, cases without an underlying pathology).3 Approximately one-fourth of all adults will experience nonspecific back pain during a 3-month period, and at any one point in time, approximately 30% of older adults suffer from back pain.4 Older adults are particularly vulnerable to back pain and most who experience nonspecific back pain have future recurrences4,5; thus, it is among the most common reasons older Americans visit physicians.6

With more than 100 million visits for spine conditions each year,7,8 the chiropractic profession is the largest health service that operates outside of the conventional medical system9,10 and the only such service reimbursed by Medicare.11,12 Medicare beneficiaries can use chiropractic care without a medical referral; however, the only reimbursable modality is manual therapy, which costs approximately $30 to $50 per visit. Chiropractors cannot be reimbursed directly for diagnostic imaging nor prescribe medications. In light of the ongoing debate regarding coverage of presumably nonessential services, there is a specific need to more rigorously examine how chiropractic care may affect national healthcare spending.

Previous observational research that has examined spending among chiropractic patients compared with medical care patients suggests that chiropractic care may reduce utilization of and expenditures on medical services for back pain.13,14 Traditional observational studies use assignment of patients to a specific treatment type (eg, chiropractic vs usual care) to study the cost of chiropractic care. These designs, however, are unable to account for the potential impacts from those who choose to use chiropractic care in place of medical care. To date, previous studies have neglected to consider such indirect effects of the service on the system at large.

Therefore, we performed a quasi-experimental study to examine how accessibility of chiropractic care among Medicare beneficiaries affects healthcare spending for spine conditions. To do so, we used a cohort of older adults in Medicare with back and/or neck pain who relocated and experienced a change in geographic accessibility of chiropractic care. In this way, the change in accessibility of chiropractic care served as a proxy for access to the service among Medicare beneficiaries, providing us with the unique opportunity to observe how either reducing or increasing access affects spine-related spending among older adults.


We examined the effect of accessibility of chiropractic care on spine-related spending using a quasi-experimental design. For our study, we geocoded Medicare beneficiaries and identified a cohort with back and/or neck pain who relocated once from 2010 to 2014. Then, using the variable-distance enhanced 2-step floating catchment area method15,16 to estimate provider to population ratios, we determined the effect of a change in accessibility of chiropractic care on spine-related spending. This method for estimating provider accessibility is the gold standard because it has a higher resolution that incorporates travel time, takes into account the location of healthcare in adjacent areas, and is less affected by choice of geographic scale.

As our study used administrative claims and publicly available data on healthcare providers, it received an expedited review by the University of Michigan Health Sciences and Behavioral Sciences Institutional Review Board.

Study Population

First, we identified all older adults (65 years and older) enrolled in Medicare Part B throughout 2010 to 2014—this resulted in the identification of 16,842,729 beneficiaries (eAppendix Figure 1 [eAppendix available at]). For each calendar year, we merged beneficiary residential zip codes with hospital referral regions (HRRs) that represent the 306 regional US healthcare markets. We then identified 986,076 beneficiaries who relocated at least once by changing HRR. We restricted our sample to the 887,917 beneficiaries who relocated only once during the 5-year time period—634,935 had at least 1 year of data prior to and after the relocation (eAppendix Figure 2).

Of those 634,935, we identified 84,679 beneficiaries who had a back and/or neck pain visit using an established list of International Classification of Disease, Ninth Revision, Clinical Modification codes for spine conditions.17 Our aim was to identify a cohort of beneficiaries who had back and/or neck pain prior to relocation (ie, those most likely to be affected by accessibility of chiropractic care). Therefore, we restricted our sample to beneficiaries who had 2 separate claims for back or neck pain at least 4 months apart in the year prior to relocation.

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