Prevalence and Geographic Variations of Polypharmacy Among West Virginia Medicaid Beneficiaries

Background: West Virginia (WV) residents are at high risk for polypharmacy given its considerable chronic disease burdens. Objective: To evaluate the prevalence, correlates, outcomes, and geographic variations of polypharmacy among WV Medicaid beneficiaries. Methods: In this cross-sectional study, we analyzed 2009-2010 WV Medicaid fee-for-service (FFS) claims data for adults aged 18-64 (N=37,570). We defined polypharmacy as simultaneous use of drugs from five or more different drug classes on a daily basis for at least 60 consecutive days in one year. Multilevel logistic regression was used to explore the individual- and county-level factors associated with polypharmacy. Its relationship with healthcare utilization was assessed using negative binomial regression and logistic regression. The univariate local indicators of spatial association method was applied to explore spatial patterns of polypharmacy in WV. Results: The prevalence of polypharmacy among WV Medicaid beneficiaries was 44.6%. High-high clusters of polypharmacy were identified in southern WV, indicating counties with above-average prevalence surrounded by counties with above-average prevalence. Polypharmacy was associated with being older, female, eligible for Medicaid due to cash assistance or medical eligibility, having any chronic conditions or more chronic conditions, and living in a county with lower levels of education. Polypharmacy was associated with more hospitalizations, emergency department visits, and outpatient visits, as well as higher non-drug medical expenditures. Conclusions: Polypharmacy was prevalent among WV Medicaid beneficiaries and was associated with substantial healthcare utilization and expenditures. The clustering of high prevalence of polypharmacy in southern WV may suggest targeted strategies to reduce polypharmacy burden in these areas.