B40-06 The Impact of Prior Authorization Policy on Access to Maintenance Inhaled Therapies for COPD in British Columbia

Rationale

Only 16% of patients with chronic obstructive pulmonary disease (COPD) in British Columbia (BC) receive maintenance inhaled therapies that are concordant with evidence-based clinical guidelines. Long-acting muscarinic antagonists (LAMA), the preferred initial therapy for treatment of COPD are underutilized, while inhaled corticosteroids (ICS)/long-acting beta agonist (LABA) combination therapy among patients at low risk of acute exacerbations accounts for over 60% of guideline-discordant use. In July 2020, BC’s universal drug plan removed the requirement for prior authorization to receive coverage for the most common LAMA medications, and simultaneously restricted coverage for ICS/LABA. We evaluated the impact of this policy change on guideline-concordant inhaler use.

Methods

We conducted a population-based cohort study using administrative health data from BC. We used a validated case definition to identify patients with COPD and followed them from January 2019-December 2022; 18 months before and after the policy change. Using interrupted time series analysis, we evaluated monthly ICS/LABA and LAMA use based on the proportion of patients filling a prescription, mean canisters dispensed, proportion of days covered (PDC), rates of ICS/LABA discontinuation and LAMA (re)initiation (≥90 day gap between prescriptions), or initiating LAMA as first-line therapy following diagnosis. Outcomes are reported as the absolute difference in observed versus counterfactual estimates at the end of the study period.

Results

The cohort included 47,583 patients with COPD contributing 1,508,091 person-months of observation (mean age 71.5 years, 46.5% female, mean follow-up 31.7 months). Eighteen months post policy, the proportion of patients filling an ICS/LABA prescription decreased by 1.3% (95% CI -2.4, -0.3), while LAMA use increased by 0.8% (95% CI 0.1, 1.6) There was no significant change in the number of ICS/LABA canisters dispensed, PDC or proportion discontinuing ICS/LABA after the policy change. Mean LAMA canisters dispensed increased by 9.8 per 1,000 patients (95% CI 1.0, 18.7) and PDC increased by 1.5% (95% CI 0.5, 2.4). The proportion of patients (re)initiating LAMA or initiating LAMA as first-line therapy increased by 0.2% (95% CI 0.02, 0.3) and 34.8% (95% CI 22.3, 48.6, Figure 1), respectively. There was no significant change in the total cost of LAMA and ICS/LABA combined.

Conclusions

Changes to public drug coverage in BC significantly improved guideline-concordant medication use. Removing restrictions on public drug coverage for LAMA substantially increased its use overall and as first-line therapy, while ICS/LABA use declined modestly after coverage was restricted. Reimbursement policy is an important tool for improving evidence-based COPD treatment.

This abstract is funded by: Lung Health Foundation