Impact of a co-pay accumulator adjustment program on specialty drug adherence

To assess the impact of a co-pay accumulator adjustment program (CAAP) on usage patterns of autoimmune specialty drugs, comparing health savings account (HSA) or preferred provider organization (PPO) plan enrollees before and after implementation of the CAAP.

Retrospective cohort analysis.

Data on HSA and PPO patients with autoimmune specialty drug use were drawn from the Conduent pharmacy benefit manager for January 2016 to October 2017 from 15 self-insured employers initiating a CAAP in January 2017. Outcomes included monthly mean fills per person, therapy discontinuation, and proportion of days covered (PDC). Linear regressions, Kaplan-Meier survival curves, and Cox proportional hazards models assessed differences while adjusting for patient characteristics.

There were 365 HSA and 238 PPO patients. After the CAAP implementation, for HSA versus PPO patients, adjusted trends in monthly fills per person decreased more rapidly, the risk of treatment discontinuation was significantly higher, and PDC was significantly lower. Prior to the CAAP, these metrics were not statistically different between groups except in 1 case. To help place the post-CAAP adjusted differences in trends in context, by the end of October 2017, 10 months after the CAAP start, HSA patients had 233 fewer autoimmune drug fills per 1000 patients, 20 percentage points higher treatment discontinuation, and 12 percentage points lower PDC.

After the CAAP, HSA patients on autoimmune drugs had significantly lower monthly fill rates, higher risk of discontinuation, and lower PDC than did PPO patients, suggesting that CAAPs have the potential to negatively affect specialty drug use.