Medication Regimen Complexity and Hospital Readmission for an Adverse Drug Event

Background: Adverse drug events (ADEs) are costly, dangerous, and often preventable. Little is known about the link between medication regimen complexity and rehospitalization as a result of an ADE. Objective: The objective of this study was to compare admission and discharge medication regimen complexity in 2 cohorts: patients readmitted for an ADE within 30 days and patients not readmitted for an ADE. Methods: The study used a retrospective parallel-group case-control design. Participants from 4 urban acute care hospitals were included in the revisit cohort if they were rehospitalized within 30 days as a result of an adverse event coded as accidental poisoning. The no-revisit cohort was formed by randomly sampling patients with the same disease classification codes as the revisit group but without history of a readmission within 30 days. Complexity of medication regimens at the initial admission and discharge was quantified with the medication regimen complexity index (MRCI). Results: The revisit group comprised 92 individuals and the no-revisit group, 228. The revisit group had a significantly higher MRCI score at admission and discharge than the no-revisit group (all P < .005). Receiver operating characteristic curves, used to determine a potential MRCI cutoff score for risk of an ADE, revealed MRCI scores of 8 or greater to optimally predict increased risk for readmission caused by an ADE. Conclusions: Complex medication regimens at hospital admission are predictive of rehospitalizations for ADEs. This finding suggests that medication regimen complexity be considered as a target for interventions to decrease the risk for readmission.