Cost-related prescription nonadherence in the United States and Canada: a system-level comparison using the 2007 International Health Policy Survey in Seven Countries.

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%).