Looking beyond polypharmacy: quantification of medication regimen complexity in the elderly.

Abstract Background Polypharmacy has been shown to influence outcomes in elderly patients. However, the impact of medication regimen complexity, quantified by the Medication Regimen Complexity Index (MRCI), on health outcomes after discharge of elderly patients has not been studied. Objective Our aim was to test the convergent, discriminant, and predictive validity of the MRCI in older hospitalized patients with varying functional and cognitive levels. Methods We retrospectively applied the MRCI to the medication regimen of 212 hospitalized patients and assessed its validity. Results The mean (SD) MRCI scores for medication regimens and number of medications at discharge were 30.27 (13.95) and 5.95 (2.40), respectively. The MRCI scores were strongly correlated with the number of medications ( r  = 0.94, P r  = 0.87, P P r  = 0.40, r  = 0.46, P P r  = −0.188, P  = 0.028); however, no such correlation was found regarding the number of medications at discharge. Conclusions The MRCI showed satisfactory validity and good evidence of classifying regimen complexity over a simple medication count. The MRCI demonstrated application in clinical research and practice in the elderly. However, more studies are needed to investigate its advantage over the number of medications for identifying patients with complex medication regimens and directing interventions to simplify their medication regimen complexity.