Background: Evaluations of drug cost-sharing policies within the same population are needed for a fair comparison of different options.
Objective: The aim of this work was to analyze the impact of 2 changes in a public drug insurance plan on the use of inhaled medications in British Columbia (BC), Canada.
Methods: Data for the period from 1997 to 2004 were used to assess whether changes in the use of steroid, beta2-agonist, and anticholinergic inhalers were associated with insurance-plan changes in a large, natural experiment involving all BC residents aged>or=65 years. The 3 sequential policies included full coverage, fixed copayments at the beginning of 2002, and 25% coinsurance with an income-based deductible beginning May 1, 2003. Linkable prescription, physician billing, hospitalization, and mortality records were obtained from the BC Ministry of Health Services. From the total population of residents aged>or=65 years, we extracted data for all patients to whom inhaled steroids, beta2-agonists, or anticholinergics were dispensed on or after January 1, 1997. Multivariable linear regression was used to estimate inhaler use during a 60-month baseline period and during implementation of the subsequent copayment and coinsurance plus deductible policies. We used logistic regression to identify predictors of initiation and cessation use of inhaled medications among older patients.
Results: Use declined for inhaled steroids (-12.3%; P<0.001), inhaled anticholinergics (-12.2%; P<0.001), and inhaled beta2-agonists (-5.8%; P<0.001). Patients with new diagnoses of asthma or chronic obstructive pulmonary disease were 25% (95% CI, 14%-31%) less likely to initiate treatment with inhaled steroids when covered by the copayment or coinsurance plus deductible policies than when they had full coverage. Chronic users of inhaled steroids were 47% (95% CI, 40%-55%) more likely to cease treatment when they were covered by the copayment policy and 22% (95% CI, 15%-29%) more likely to cease when covered by the coinsurance plus deductible policy than when they had full coverage.
Conclusions: The copayment and coinsurance plus deductible policies were associated with significant reductions in use of inhaled medications, mostly due to decreased initiation and increased cessation rates. However, the consequences of these policies on health outcomes have not yet been determined.