RESUMO
BACKGROUND: The prevalence of medication nonadherence among Malaysian older adults is approximately 60%. However, there is a lack of studies assessing the factors associated with medication nonadherence among this population. This research aims to explore the association between medication regimen complexity (MRC), treatment satisfaction and medication adherence among Malaysian older adults. METHOD: A cross-sectional study was conducted in outpatient clinics of a teaching hospital in Pahang, Malaysia, between April 2023 and September 2023. MRC Index (MRCI), Treatment Satisfaction for Medication version II (TSQM v.II), and the Malaysian Medication Adherence Assessment Tool (MyMAAT) were used. Multivariate linear and logistic regression models were performed to test the factors affecting treatment satisfaction and medication adherence. Mediator analysis was implemented to assess the mediating role of treatment satisfaction. RESULT: The study involved 429 Malaysian older adult patients, with a prevalence of nonadherence of 51.0% (n = 219) and an MRCI mean score of 17.37 (SD = 7.07). The mean overall treatment satisfaction score was 73.91 (SD = 15.23). Multivariate logistic regression analysis expressed four significant predictors associated with nonadherence: MRC (AOR = 1.179, p = 0.002), overall treatment satisfaction (AOR = 0.847, p < 0.001), partially self-managed medication (AOR = 2.675, p = 0.011) and fully managed medication by family members/caregivers (AOR = 8.436, p = 0.004). Multivariate linear regression shows three predictors of treatment satisfaction: MRC (ß = -1.395, p < 0.001), Charlson Comorbidity Index (CCI) (ß = -0.746, p = 0.009) and self-managed medication (ß = 5.554, p = 0.006). Mediator analysis indicated that treatment satisfaction partially mediated the association between MRC and nonadherence. CONCLUSION: Nonadherence was quite prevalent among Malaysian older outpatients and was associated with regimen complexity, treatment satisfaction and patient dependence on others to manage their medications. Future studies should focus on interventions to control the factors that negatively affect patients' medication adherence.