Effect of the Medicare Part D coverage gap on medication use among patients with hypertension and hyperlipidemia.

BACKGROUND Prior studies of the Medicare Part D coverage gap are limited in generalizability and scope. OBJECTIVE To determine the effect of the coverage gap on drugs used for asymptomatic (antihypertensive and lipid-lowering drugs) and symptomatic (pain relievers, acid suppressants, and antidepressants) conditions in elderly patients with hypertension and hyperlipidemia. DESIGN Quasi-experimental study using pre-post design and contemporaneous control group. SETTING Medicare claims files from 2005 and 2006 for 5% random sample of Medicare beneficiaries. PATIENTS Part D plan enrollees with hypertension or hyperlipidemia aged 65 years or older who had no coverage, generic-only coverage, or both brand-name and generic coverage during the gap in 2006. Patients who were fully eligible for the low-income subsidy served as the control group. MEASUREMENTS Monthly 30-day supply prescriptions available, medication adherence, and continuous medication gaps of 30 days or more for antihypertensive or lipid-lowering drugs; monthly 30-day supply prescriptions available for pain relievers, acid suppressants, or antidepressants before and after coverage gap entry. RESULTS Patients with no gap coverage had a decrease in monthly antihypertensive and lipid-lowering drug prescriptions during the coverage gap. Nonadherence also increased in this group (antihypertensives: odds ratio [OR], 1.60 [95% CI, 1.50 to 1.71]; lipid-lowering drugs: OR, 1.59 [CI, 1.50 to 1.68]). The proportion of patients with no gap coverage who had continuous medication gaps in lipid-lowering medication use and antihypertensive use increased by an absolute 7.3% (OR, 1.38 [CI, 1.29 to 1.46]) and 3.2% (OR, 1.35 [CI, 1.25 to 1.45]), respectively, because of the coverage gap. Decreases in use were smaller for pain relievers and antidepressants and larger for acid suppressants in patients with no gap coverage. Patients with generic-only coverage had decreased use of cardiovascular medications but no change in use of drugs for symptomatic conditions. No measures changed in the brand-name and generic coverage groups. Results of sensitivity analyses were consistent with the main findings. LIMITATION Because this study was nonrandomized, unobserved differences may still exist between study groups. CONCLUSION The Part D coverage gap was associated with decreased use of medications for hypertension and hyperlipidemia in patients with no gap coverage and generic-only gap coverage. The proposed phasing out of the gap by 2020 will benefit such patients; however, use of low-value medications may also increase. PRIMARY FUNDING SOURCE Penn-Pfizer Alliance and American Heart Association.