The impact of permissive and restrictive pharmaceutical policies on quetiapine dispensing: Evaluating a policy pendulum using interrupted time series analysis

Purpose: To evaluate the impact of 2 policy changes on quetiapine dispensing in Australia: removal of prior authorisation for prescribing (policy 1: July 2007) and removal of repeat prescriptions for 25-mg quetiapine (policy 2: January 2014). Methods: We performed an interrupted time series analysis using Pharmaceutical Benefits Scheme claims data (July 2005 to December 2015). We assessed the impact of both policies on monthly quetiapine dispensing (25 mg and >25 mg) and the impact of policy change 2 on monthly rates of 25-mg discontinuation and switching from 25 mg to other quetiapine strengths. We also estimated the impact of both policies on the proportion of people with potentially inappropriate therapy (no evidence of dose escalation) following 25-mg initiation. Results: Following removal of prior authorisation, 25-mg and >25-mg quetiapine dispensing in the Pharmaceutical Benefits Scheme 10% sample increased by 11/month (95% CI: 2–21) and 14/month (95% CI: 8–20), respectively. After removing 25-mg repeats, there was a permanent decrease of 1072 (95% CI 773–1371) dispensings and an increase in discontinuation of this strength; 48% of people dispensed the 25-mg strength that discontinued, discontinued quetiapine completely; the remainder continued to use higher quetiapine strengths. We observed minimal switching to other quetiapine strengths. There was no change in inappropriate 25-mg therapy following policy change 1 and a small decrease (79% to 76%, P = 0.05) following policy change 2. Conclusion: More nuanced policies are needed to ensure the appropriate access to 25-mg quetiapine for dose escalation while discouraging use for indications where the evidence of risk and benefit is unclear.