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

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<0.001) and the number of daily doses (r=0.87, P<0.001) and increased as the number of medications taken ≥3 times daily increased (27.35, 34.45, and 43.00 for none, 1, and 2 drugs, respectively; P<0.001). Positive correlations were observed between the Cumulative Illness Rating Scale-Geriatrics score and both the number of medications and the MRCI score (r=0.40, r=0.46, P<0.001, respectively). No relationship was found between MRCI scores and the number of medications and age, sex, and postdischarge medication modifications. Patients nonadherent to at least 1 drug were discharged with a higher MRCI score and higher number of medications compared with medication-compliant patients (33.3 and 7.0 vs 27 and 5.8, respectively; P<0.01). An inverse correlation was found between overall adherence 1 month after discharge and the MRCI score (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.