Access to chiropractic care and the cost of spine conditions among older adults.

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.