Medication Regimen Complexity and Adherence in Patients at Risk of Medication Misadventure

Abstract

ABSTRACTBackgroundDosage forms, dosing frequencies and additional instructions contribute to regimen complexity, which in turn is known to influence treatment outcomes.AimTo evaluate the relationship between complexity of medication regimens and adherence in patients at risk of medication misadventure.MethodA modified Morisky scale was administered to inpatients during their hospital stay. Complexity of the medication regimens at the time of hospital discharge was assessed using the Medication Regimen Complexity Index.ResultsThe 310 subjects had a mean age of 72 years and were using a mean of 10.4 prescribed medications. High adherence was self‐reported by 198 (64%) patients. Unintentional nonadherent behaviour was evident in 80 (26%) patients, while 51 (17%) patients admitted making intentional deviations from the recommended treatment. The reliability of the Morisky scale was poor (α = 0.38; 0.26–0.49). Patients who stopped taking their medicine when feeling worse had significantly less complex (p = 0.01) 'additional instructions' (median 4; 1–12) than those who did not stop their medicines (median 6; 0–18). This association was independent of age, gender and other medication regimen features. There were no significant differences between medication regimen features of patients who were forgetful, careful, and who stopped their medications when feeling better and their respective counterparts.ConclusionPatients using medications with less complex additional instructions were more likely to stop taking their medicine when feeling worse. Interventions designed to improve adherence by reducing regimen complexity are unlikely to be effective in all patients, especially in those with intentional nonadherence.