Effect of a prior authorization process on antiplatelet therapy and outcomes in patients prescribed clopidogrel following coronary stenting

BACKGROUND: Alberta Blue Cross (ABC) provides copayment-based coverage for residents older than 65 years. A prior authorization (PA) process for patients prescribed clopidogrel following stent insertion was changed to an authorized prescriber (AP) list process in March 2002. OBJECTIVE: To determine the effect of a policy change in medication coverage for clopidogrel on patients' filling of prescriptions and outcomes following stent insertion. METHODS: Consecutive patients who received a coronary stent between September 1, 2001, and August 31, 2002, at the University of Alberta Hospital and were eligible for ABC coverage were identified. Data were obtained from the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease and ABC databases. RESULTS: One hundred twelve patients (45 in the PA period and 67 in the AP period) who received a coronary stent were eligible for ABC coverage during the study period. The two cohorts of patients were similar with respect to demographics. Fewer patients in the PA period than in the AP period had their prescription filled on the day of discharge (31% versus 54%; P=0.02), and the median time to fill was four days versus zero days in the PA and AP periods, respectively (Wilcoxon P=0.04). There was no significant difference in the proportion of patients filling their prescriptions after 28 days from discharge (67% versus 75%, P = not significant) or in the overall comparison of time to fill (log rank P=0.22). Two repeat revascularization procedures were necessary within six weeks after stent placement; both were in PA period patients who delayed or failed to fill their prescription. CONCLUSIONS: The PA process may have delayed patients filling clopidogrel prescriptions following hospital discharge and has the potential to contribute to negative clinical consequences.