The relationship between emergency department use and cost-related medication nonadherence among Medicare beneficiaries

Abstract

Study objective: The objective of this study was to evaluate the relationship between self-reported cost-related nonadherence to prescription medications and emergency department (ED) utilization among Medicare beneficiaries. We hypothesized that persons who report cost-related medication nonadherence would have subsequent higher ED use.

Methods: We conducted a retrospective cohort study of continuously enrolled Medicare beneficiaries in 2006 and 2007. We used multivariate logistic regression to evaluate the relationship between ED use and cost-related medication nonadherence. Our principal dependent variable was any ED visit within a 364-day period after an interview assessing cost-related medication nonadherence. Our principal independent variables both denoted cost-related medication nonadherence: mild cost-related medication nonadherence, defined as a reduction in dose or a delay in filling medications because of cost; and severe cost-related medication nonadherence, defined as not filling a medication at all because of cost.

Results: Our sample consisted of 7,177 Medicare Current Beneficiary Survey respondents. Approximately 7.5% of respondents reported mild cost-related medication nonadherence only (n=541) and another 8.2% reported severe cost-related medication nonadherence (n=581). Disabled Medicare beneficiaries with severe cost-related medication nonadherence were more likely to have at least 1 ED visit (1.53; 95% confidence interval 1.03 to 2.26) compared with both disabled Medicare beneficiaries without cost-related medication nonadherence and elderly Medicare beneficiaries in all cost-related medication nonadherence categories.

Conclusion: Our results show an association between severe cost-related medication nonadherence and ED use. Disabled beneficiaries younger than 65 years who report severe cost-related medication nonadherence were more likely to have at least 1 ED visit, even when adjusting for other factors that affect utilization.

Figure 1. Percentage of persons with 0, 1, 2, 3, and 4 or more visits, by age and eligibility categories*

* Weighted to National Medicare Population, includes missing observations.

Figure 2. Adjusted Predicted Percentages, Any ED Visit, by CRN and eligibility categories*

* Predicted probabilities of percentages of persons with at least one ED visit from multivariate logistic regression, weighted to national Medicare population. Excludes missing observations. Error Bars Represent 95% CI (Predicted from multivariate logistic regression analysis controlling for variables in Table 2.)

Figure 3. Adjusted predicted average number of ED visits, by CRN and eligibility categories*

* Predicted probabilities of average number of ED visits from multivariate Poisson regression, Excludes missing observations. Weighted to National Medicare Population. Error Bars Represent 95% CI^, (Predicted from multivariate Poisson regression analysis controlling for variables identified in Table 3.)