Chiropractic use and changes in health among older medicare beneficiaries: a comparative effectiveness observational study.
OBJECTIVE
The purpose of this study was to investigate the effect of chiropractic on 5 outcomes among Medicare beneficiaries: increased difficulties performing activities of daily living (ADLs), instrumental ADLs (IADLs), and lower body functions, as well as lower self-rated health and increased depressive symptoms.


METHODS
Among all beneficiaries, we estimated the effect of chiropractic use on changes in health outcomes among those who used chiropractic compared with those who did not, and among beneficiaries with back conditions, we estimated the effect of chiropractic use relative to medical care, both during a 2- to 15-year period. Two analytic approaches were used--one assumed no selection bias, whereas the other adjusted for potential selection bias using propensity score methods.


RESULTS
Among all beneficiaries, propensity score analyses indicated that chiropractic use led to comparable outcomes for ADLs, IADLs, and depressive symptoms, although there were increased risks associated with chiropractic for declines in lower body function and self-rated health. Propensity score analyses among beneficiaries with back conditions indicated that chiropractic use led to comparable outcomes for ADLs, IADLs, lower body function, and depressive symptoms, although there was an increased risk associated with chiropractic use for declines in self-rated health.


CONCLUSION
The evidence in this study suggests that chiropractic treatment has comparable effects on functional outcomes when compared with medical treatment for all Medicare beneficiaries, but increased risk for declines in self-rated health among beneficiaries with back conditions.