Background: Prior research indicates that residents of the United States are nearly twice as likely as Canadian residents to report cost-related nonadherence (CRNA) (ie, being unable to fill > or =1 prescription due to cost). However, these kinds of national comparisons obscure important within-country differences in insurance coverage.
Objective: This study was designed to compare rates of CRNA across major financing systems for prescription drugs in the United States and Canada.
Methods: This study used the 2007 International Health Policy Survey in Seven Countries (supported by the US Commonwealth Fund) to estimate rates of CRNA in the following health systems: Canadian compulsory coverage (Quebec), Canadian senior and social assistance coverage (Ontario), Canadian income-based coverage (British Columbia, Manitoba, and Saskatchewan), Canadian mixed coverage (all other provinces), US private coverage (employer-based or individual insurance), US senior and social assistance coverage (Medicare and/or Medicaid), and US no coverage (uninsured).
Results: Adults in the United States were far more likely than adults in Canada to report CRNA (23.1% vs 8.0%; chi(2) = 147.4; P < 0.001). Seniors (> or =65 years of age) were less likely than younger adults (<65 years) to report CRNA in both the United States (9.2% vs 25.8%; chi(2) = 64.3; P < 0.001) and Canada (4.6% vs 8.7%; chi(2) = 14.9; P < 0.001), presumably due to categorical eligibility for prescription drug insurance. Comparative analyses therefore focused on working-age adults (<65 years). Adults in Quebec (who have compulsory drug coverage) were only half as likely as those in Ontario to report CRNA (odds ratio [OR] = 0.5; 95% CI, 0.3-0.8). Uninsured adults in the United States were >7 times as likely to report CRNA (OR =7.2; 95% CI, 5.0-10.5), and adults with public insurance (OR = 2.2; 95% CI, 1.4-3.5) and private insurance (OR = 2.2; 95% CI, 1.6-3.0) were >2 times as likely to report CRNA.
Conclusions: After stratifying by age and simultaneously adjusting for sex, household income, and chronic illness, large differences in CRNA were found between and within countries. Even in a compulsory prescription insurance system like that in Quebec, 4.4% of working-age adults reported CRNA. However, these rates were low compared with CRNA rates for working-age adults in the United States who lack any health insurance (43.3%).