Identifying Adherence Patterns Across Multiple Medications and Their Association With Health Outcomes in Older Community-Dwelling Adults With Multimorbidity

Objectives: To classify older people with multimorbidity according to their adherence patterns and to examine the association between medication adherence and health outcomes. Methods: This is a secondary analysis of a cohort study. Community-dwelling adults aged >= 70 years were recruited from 15 general practices in Ireland in 2010 (wave 1) and followed up 2 years later (wave 2). Participants had RxRisk-V multimorbidity conditions at wave 1 and had dispensations of RxRisk-V medications (wave 1-wave >= 2). Average adherence across RxRisk-V conditions was estimated based on continuous multiple-interval measure of medication availability (CMA7 function in AdhereR). Group-based trajectory models were used to group participants' adherence patterns for RxRisk-V medications. Multilevel regression was used to examine the association between adherence and (1) EuroQol 5-dimension (EQ-5D) utility (linear) and (2) vulnerability, using the Vulnerable Elders Survey (3 defined as vulnerable; logistic) at wave 2, controlling for potential confounders. Results: Average adherence (CMA7) was 77% across 501 participants. Group-based trajectory models identified 5 adherence groups: (1) initial low adherers, gradual increase; (2) high adherers, sharp decline; (3) steady adherers, gradual decline; (4) consistent high adherers; and (5) consistent nonadherers. Higher average adherence was associated with a significant increase in EQ-5D utility (adjusted beta = 0.11, robust standard error 0.04). Group 5 was associated with significantly increased vulnerability compared to group 4 (adjusted odds ratio = 1.88; 95% confidence interval 1.01-3.50). Conclusion: Increased average adherence was associated with higher EQ-5D utility. Adherence grouping did not significantly impact utility. Suboptimal adherence to multiple medications in older adults with multimorbidity was associated with vulnerability.