Medication Regimen Complexity and Polypharmacy as Factors Associated With All-Cause Mortality in Older People: A Population-Based Cohort Study

Objectives: To investigate whether medication regimen complexity and/or polypharmacy are associated with all-cause mortality in older people. Methods: This was a population-based cohort study among community-dwelling and institutionalized people >= 60 years old (n = 3348). Medication regimen complexity was assessed using the 65-item Medication Regimen Complexity Index (MRCI) in 10-unit steps. Polypharmacy was assessed as a continuous variable (number of medications). Mortality data were obtained from the Swedish National Cause of Death Register. Cox proportional hazard models were used to compute unadjusted and adjusted hazard ratios (HRs) and 95% Cls for the association between regimen complexity and polypharmacy with all-cause mortality over a 3-year period. Subanalyses were performed stratifying by age (<= 80 and>80 years), sex, and cognition (Mini-Mental State Examination [MMSE] <26 and >= 2.6). Results: During follow-up, 14% of the participants (n = 470) died. After adjusting for age, sex, comorbidity, educational level, activities of daily living, MMSE, and residential setting, a higher MRCI was associated with mortality (adjusted HR = 1.12; 95% CI = 1.01-1.25). Polypharmacy was not associated with mortality (adjusted HR = 1.03; 95% Cl = 0.99-1.06). When stratifying by sex, both MRCI and polypharmacy were associated with mortality in men but not in women. MRCI was associated with mortality in participants <= 80 years old and in participants with MMSE but not in participants >80 years old or with MMSE <26. Conclusion: Regimen complexity was a better overall predictor of mortality than polypharmacy. However, regimen complexity was not predictive of mortality in women, in participants >80 years old, or in those with MMSE<26. These different associations with mortality deserve further investigation.