The effects of catastrophic drug plan deductibles on older women's use of cardiovascular medicines: a retrospective cohort study.

Background: In recent years, some provinces have implemented income-based catastrophic drug coverage in an effort to provide universal drug coverage while limiting government liability for the escalating costs of medicines needed for an aging population. We sought to examine the effects of income-based deductibles under British Columbia's Fair PharmaCare system on older patients' use of cardiovascular medicines in 2013, 10 years after the province's policy change.

Methods: Using linked administrative databases, we studied rates of hypertension and cholesterol medication used by 2 cohorts of older, married women who had different levels of public drug subsidy based solely on their spouses' ages. We compare measures of 2013 medication use by study cohorts using statistical models that controlled for age, general health status, indicators of need for specific drug classes, ethnicity, rural residence and household income.

Results: Among members of our study cohorts, the odds of filling cardiovascular prescriptions in 2013 were influenced by patient age, general health status, drug-specific diagnoses, ethnicity, place of residence and household income. For women with household incomes less than $50 000 (42% of our study population), having preferential public drug coverage by way of spousal age was associated with a 15% increase in the adjusted odds of filling 1 or more prescription for hypertension treatment (adjusted odds ratio [OR] 1.15, 95% confidence interval [CI] 1.06 to 1.24) and a 13% increase in the adjusted odds of filling 1 or more prescription for cholesterol treatments (adjusted OR 1.13, 95% CI 1.06 to 1.21). There were no statistically significant effects on the number of days of therapy purchased per user of these cardiovascular medicines.

Interpretation: We have found that the level of income-based deductibles under catastrophic drug benefi t plans can affect the use of cardiovascular drug treatments, even long after deductibles are put in place. These results add to the body of evidence in support of the idea that public drug coverage design can affect access to necessary medications.