Prior Authorization and Association With Delayed or Discontinued Prescription Fills.

Purpose: Prior authorization requirements are increasing but little is known about their effects on access to care. We examined the association of a new prior authorization policy with delayed or discontinued prescription fills for oral anticancer drugs among Medicare Part D beneficiaries.

Methods: Using Medicare part D claims data from 2010 to 2020, we studied beneficiaries regularly filling one of 11 oral anticancer drugs, defined as three 30-day fills in 120 days preceding the plan's prior authorization policy change on that drug and continuously enrolled in the same plan for 120 days before and after the policy change at the start of a new year. The control group consisted of beneficiaries meeting the same utilization criteria, but who were enrolled in plans at the same time that did not implement a prior authorization policy change. The outcomes of interest were discontinuation of the drug within 120 days (analyzed with regression analyses) and time (in days) to next fill after a prior authorization policy change (analyzed using a quasi-experimental difference-in-differences event study).

Results: The introduction of a new prior authorization on an established drug increased the odds of discontinuation within 120 days (adjusted odds ratio, 7.1 [95% CI, 6.0 to 8.5]; < .001) and increased time to next fill by 9.7 days (95% CI, 8.2 to 11.2; < .001), relative to patients whose plans did not have a prior authorization policy change.

Conclusion: Introduction of a new prior authorization policy on an established drug regimen is associated with increased probability of discontinued and delayed care. For some conditions, this may represent a clinically consequential barrier to access. Waiving prior authorization for patients already established on a drug may improve adherence.