U.S. emergency departments visits resulting from poor medication adherence: 2005-07

Objectives: To describe characteristics and trends for emergency department visits related to medication nonadherence and to identify associations between patient characteristics and emergency department visits related to medication nonadherence. Design: Retrospective cross-sectional study. Setting: National Hospital Ambulatory Medical Care Survey (NHAMCS) from 2005 to 2007. Patients: Patients who had an emergency department visit for medication nonadherence. Intervention: NHAMCS data were weighted to yield national estimates of emergency department visits related to medication nonadherence. Descriptive frequencies were calculated for visits related and unrelated to medication adherence. A binary logistic regression model was used to identify covariates for nonadherence. Main outcome measures: National estimates of emergency department visits related to medication nonadherence. Results: An estimated 456,209 +/- 68,940 (mean +/- SD) nonadherence-related visits occurred. Of visits related to nonadherence, 29% resulted from mental health disorders. Significant covariates of nonadherence-related visits included age, payment source, and primary diagnosis. Visits for patients with mental illness (odds ratio 22.74 [95% CI 14.68-34.20]), type 2 diabetes (15.80 [5.20-48.06]), nondependent abuse of drugs (11.85 [3.83-36.65]), or essential hypertension (11.06 [3.99-30.61]) were significantly associated with the probability that an emergency department visit was related to nonadherence. More than 20% of emergency department visits related to medication nonadherence resulted in hospital admission, whereas only 12.7% of visits unrelated to nonadherence resulted in hospital admission (P < 0.0001). Conclusion: Medication nonadherence is an important problem. Targeting patients at high risk for nonadherence, especially patients with mental illness, may improve medication adherence and prevent future emergency department visits.