A cross-national study of prescription nonadherence due to cost: data from the Joint Canada-United States Survey of Health.

BACKGROUND

In Canada and the United States, patients who have difficulty paying for prescribed medications are less likely to obtain them and may experience increased risks for morbidity and mortality and/or increased health care costs due to nonadherence. As prescription drug costs have risen, the ability to pay for medications has emerged as a critical public health issue.

OBJECTIVES

The objectives of this study were to estimate the rates of cost-associated nonadherence in Canada and the United States, and to identify factors that predict cost-associated nonadherence in both countries.

METHODS

This original analysis used data from the 2002/2003 Joint Canada-US Survey of Health, a household phone survey jointly conducted by Statistics Canada (Ottawa, Ontario, Canada) and the US National Center for Health Statistics (Hyattsville, Maryland). The sample included 3505 adults in Canada and 5183 adults in the United States. Weighted group comparisons and logistic regression analyses were used to identify population factors predictive of cost-associated prescription nonadherence.

RESULTS

Residents of Canada were much less likely than residents of the United States to report cost-associated nonadherence (5.1% vs 9.9%; P < 0.001). Americans without health insurance (28.2%) and Americans and Canadians without prescription-drug coverage (16.2%) were significantly more likely than those with insurance (6.2%) to report cost-associated nonadherence (P < 0.001). In addition to country of residence and insurance coverage, significant risk factors predictive of nonadherence were young age, poor health, chronic pain, and low household income.

CONCLUSIONS

The results of this analysis suggest that people with low incomes and inadequate insurance, as well as those with poor health and/or chronic symptoms, are more likely to report failing to fill a prescription due to cost. The overall rate of cost-associated nonadherence was significantly higher in the United States than in Canada, even when other person-level factors were controlled for, including health insurance and prescription-drug coverage.