Factors associated with medication regimen complexity in older people: a cross-sectional population-based study

Purpose: There is a lack of population-based research about factors associated with medication regimen complexity. This study investigated factors associated with medication regimen complexity in older people, and whether factors associated with regimen complexity were similar to factors associated with number of medications. Methods: This cross-sectional population-based study included 3348 people aged ≥60 years. Medication regimen complexity was computed using the validated 65-item Medication Regimen Complexity Index (MRCI). Multinomial logistic regression was used to compute unadjusted and adjusted odds ratios (ORs) with 95 % confidence intervals (CIs) for factors associated with regimen complexity. Multivariable quantile regression was used to compare factors associated with regimen complexity and number of medications. Results: In adjusted analyses, participants in the highest MRCI quintile (MRCI>20) were older (OR=1.04, 95 % CI 1.02;1.05), less likely to live at home (OR=0.35, 95 % CI 0.15;0.86), had greater comorbidities (OR=2.17, 95 % CI 1.89;2.49), had higher cognitive status (OR=1.06, 95 % CI 1.01;1.11), a higher prevalence of self-reported pain (OR=2.85, 95 % CI 2.16;3.76), had impaired dexterity (OR=2.39, 95 % CI 1.77;3.24) and were more likely to receive help to sort their medications (OR=4.43 95 % CI 2.39;8.56) than those with low regimen complexity (MRCI >0-5.5). Similar factors were associated with both regimen complexity and number of medications. Conclusion: Older people with probable difficulties managing complex regimens, including those with impaired dexterity and living in institutional settings, had the most complex medication regimens even after adjusting for receipt of help to sort medications. The strong correlation between regimen complexity and number of medications suggests that clinicians could use a person's number of medications to target interventions to reduce complexity.