Association of low-income subsidy, medicaid dual eligibility, and disability status with high-risk medication use among Medicare Part D beneficiaries

Background: Low-income subsidy/dual eligibility (LIS/DE) status and disability status may be associated with high-risk medication (HRM) use but are not usually accounted for in medication-use quality measures. Objective: To examine the association of: 1) LIS/DE status and HRM use; and 2) disability status and HRM use, while controlling for both health plan level effects and patient characteristics for Medicare beneficiaries enrolled in Medicare Advantage Prescription Drug Plans (MA-PD) and stand-alone Prescription Drug Plans (PDP). Methods: This retrospective cross-sectional study used 2013 Medicare data to determine if LIS/DE status and disability status were independently associated with HRM use (using the Pharmacy Quality Alliance HRM measure) in MA-PDs and PDPs. Multivariable generalized linear mixed models assessed the association of LIS/DE and HRM use, and disability and HRM use, after adjusting for health plan effect and patient-level confounders for MA-PD and PDP beneficiaries. Results: Of 520,019 MA-PD beneficiaries, 88,693 (17.1%) were LIS/DE and 48,997 (9.4%) were disabled. Of 881,264 PDP beneficiaries, 213,096 (24.2%) were LIS/DE, and 83,593 (9.5%) were disabled. LIS/DE beneficiaries had a higher percent of HRM users compared to non-LIS/DE MA-PD (13.3% vs. 9.7%, p < 0.001) and PDP (17.1% vs. 13.2%, p < 0.001) beneficiaries. Disabled beneficiaries had a higher percent of HRM users compared to non-disabled MA-PD (17.0% vs. 9.6%, p < 0.001) and PDP (22.9% vs. 13.2%, p < 0.001) beneficiaries. Multivariable analyses showed LIS/DE (adjusted odds ratio [AOR] = 1.07; 95% CI = 1.04, 1.10) and disability (AOR = 1.38; 95% CI = 1.34, 1.42) were associated with HRM use among MA-PD and PDP beneficiaries (LIS/DE AOR = 1.14; 95% CI = 1.12, 1.16; disability AOR = 1.37; 95% CI = 1.34, 1.40). Conclusions: The association of LIS/DE and disability with higher HRM use in both MA-PD and PDP beneficiaries, when controlling for health plan effects and patient characteristics, suggests these factors should be considered when comparing health plan performance on HRM measures.