Abstract 13666: Part D's Coverage Gap Reduces Cardiovascular Medication Use in a Nationally-Representative Sample of Fee-for-Service Medicare Beneficiaries with Hypertension and Hyperlipidemia
Objectives: Previous studies of Part D's coverage gap have been limited to isolated Medicare Advantage plans. This study is the first to evaluate the impact of the coverage gap on use of antihypertensive drugs (AHTDs) and lipid-lowering drugs (LLDs) among nationally-representative samples of fee-for-service (FFS) patients with hypertension and hyperlipidemia, respectively.
Methods: The two samples consisted of patients >=65 years from the 5% Medicare files with a hypertension or hyperlipidemia diagnosis in 2005 and 12-month FFS Part D coverage in 2006. Within each sample a quasi-experimental design was used to examine three groups who entered the coverage gap during 2006 and had (1) no coverage; (2) generic only coverage; and (3) brand /generic coverage during the gap. Patients whose drug spending exceeded the coverage gap threshold but faced no gap in coverage because of low-income subsidy (LIS) status formed the control group. Study outcomes included adherence (percent days covered >=0.80) and discontinuation (>=30-day continuous gap) of AHTDs or LLDs. The impact of the coverage gap was estimated using propensity score weighted generalized-estimating-equations. Subgroup analyses were conducted in patients with coronary heart disease (CHD).
Results: Among patients with hyperlipidemia, those with no coverage in the gap had lower adherence (OR=0.62, 95% CI: 0.56-0.69) and higher discontinuation (OR=1.63, 95% CI: 1.46-1.82) of LLDs compared to LIS patients. Patients with generic only coverage had reductions in brand LLD use but no significant change in generic LLD use during the gap. Similar findings were observed for AHTDs in hypertension patients. Among patients with brand/generic coverage in the gap, no statistically meaningful impact was observed on AHTDs; however, the use of brand LLDs was higher during the gap compared to LIS patients. Similar results were seen in the subgroup of CHD patients.
Conclusions: The coverage gap was associated with reductions in LLD and AHTD use; however, the effect varied based on the type of gap coverage. Similar results in CHD patients further raise concerns given their higher risk for coronary events. Elimination of the coverage gap under the health reform law may improve use of such life-saving cardiovascular drugs.
- © 2011 by American Heart Association, Inc.