Impact of prescription benefit coverage limits on sevelamer hydrochloride adherence for patients with ESRD

To assess the impact of prescription benefit coverage on medication adherence in Medicare-eligible members diagnosed with end-stage renal disease taking sevelamer hydrochloride.

This pilot study involved a retrospective analysis of patients with end-stage renal disease taking sevelamer, with an annual cap on brand prescription drug spending compared with those without a cap. We compared sevelamer adherence and discontinuation proportions between the 2 groups of Medicare patients in 2003 and 2004. Medication adherence was calculated based on the proportion of available days covered in relationship to capped versus noncapped pharmacy benefit.

Rate ratios showed that in 2003, the patients taking sevelamer under a capped benefit (N = 43) had 27% fewer days of drug use compared with those (N = 88) without a capped benefit (relative risk, 0.73; 95% CI, 0.58-0.93). Similarly, in 2004, those taking sevelamer under the capped benefit (N = 21) had 33% fewer days of drug use compared with those (N = 117) without a capped benefit (relative risk, 0.67; 95% CI, 0.46-0.96).

Medication adherence was significantly lower for patients with a capped brand-name drug benefit. These findings provide insight into potential drug utilization patterns, including for sevelamer, under the Medicare Part D benefit, where members could face significant out-of-pocket expenditures once coverage limits are reached.