Geographic variation in utilization of chiropractic and primary care for new onset neck pain among Medicare fee-for-service beneficiaries in the United States in 2021

Neck pain (NP) is a leading cause of disability among older adults. Clinical practice guidelines recommend nonpharmacological therapies as a first-line approach. However, prior studies suggest substantial geographic variability in the availability and utilization of nonpharmacological therapies in the United States. Characterizing care utilization patterns among older adults with NP yields critical insights into equitable access to, and utilization of, guideline-concordant services. Aims were to (i) investigate spatial variation in rates of outpatient provider utilization, with attention to potential disparities in access and (ii) assess predictors of initial provider specialty for new onset NP among Medicare fee-for-service (FFS) beneficiaries in 2021. We conducted a retrospective observational study, using Medicare claims data to calculate state-level rates of care utilization for NP overall and for frequently utilized provider types for NP: chiropractic and primary care. Spatial distribution of care utilization for NP and provider utilization was visualized and investigated through spatial autocorrelations. Associations between provider utilization and sociodemographic risk factors were assessed. Predictors of chiropractic and primary care utilization were analyzed using regression models. We identified 236,995 Medicare FFS beneficiaries with an outpatient visit for new onset NP. The mean state-level rate of care utilization for NP was 188.72 per 1000 beneficiaries. Northern plains and mountain states exhibited higher rates of care utilization for NP, higher chiropractic utilization, and lower primary care utilization. Chiropractic care utilization was positively associated with better population health status and low back pain (LBP) prevalence, whereas LBP prevalence was negatively associated with primary care utilization. This study demonstrates significant geographic variation in utilization for NP by provider specialty among Medicare FFS beneficiaries, and significant associations between provider utilization and sociodemographic factors. Future research should investigate disparities in care access and utilization for NP across sociodemographic groups to inform efforts toward health equity.