The association between medication regimen complexity, treatment satisfaction and medication adherence among Malaysian older adult outpatients in Sultan Ahmad Shah Medical Centre@IIUM (SASMEC@IIUM)

Abstract

In 2022, Malaysia has become an ageing nation, where older adults make up about 7.3% of the national population. Older adults constitute the majority of medicine consumers. However, there is a scarcity of research examining the factors influencing medication non-adherence among the Malaysian older adults. This research aimed to explore the association between medication regimen complexity (MRC), treatment satisfaction and medication adherence within this population. A cross-sectional study was conducted in the outpatient settings of Sultan Ahmad Shah Medical Centre@IIUM, from February to September 2023. The study utilised three assessment tools: Medication Regimen Complexity Index (MRCI), Malay Treatment Satisfaction for Medication Version II (M-TSQM v.II), and Malaysia Medication Adherence Assessment Tool (MyMAAT). The research applied multivariate linear and logistic regression models to determine the predictors of MRC, treatment satisfaction and medication adherence. Additionally, mediation analysis was implemented to assess the mediating role of treatment satisfaction for the association between MRC and non-adherence. Initially, a cross-cultural adaptation of M-TSQM v.II was conducted and it included translation, validation, and reliability testing of the questionnaire. For the cross-cultural adaptation of M-TSQM v.II, the study achieved excellent content validity, with high scores for "Relevance" and good scores for "Clarity". Reliability testing of constructs demonstrated good internal consistency, with all Cronbach's ? values of each domain exceeding 0.7. Convergent validity was established with Average Variance Extracted (AVE) values of ?0.5 for every construct. Construct validity, assessed through confirmatory factor analysis (CFA), indicated a robust model fit with favourable fitness indexes. M-TSQM v.II is valid, reliable and psychometrically sound for the Malaysian older adult population. The study included 429 patients with a mean age of 71.98 ± 5.5, and 51.0% (n=217) were non-adherent to their medications. The average total score for MRC was 17.38 ± 7.07, while overall treatment satisfaction, assessed across four domains in TSQM v.II (Effectiveness, Side Effects, Convenience, and General Satisfaction), scored an average of 73.91 ± 15.23. Multivariate logistic regression analysis identified four significant determinants associated with non-adherence: MRC, overall treatment satisfaction, partially self-managed medication, and fully managed medication by caregivers. Furthermore, multivariate linear regression analysis revealed three significant determinants influencing treatment satisfaction: MRC, Charlson Comorbidity Index (CCI), and self-managed medication. Additionally, a mediation analysis unveiled the partial mediating role of treatment satisfaction in the association between MRC and non-adherence. In conclusion, the leading factors contributing to non-adherence among Malaysian older adult have been identified in this study, which signifies the greater need for evaluation of regimen simplification, the patient-centred approach based on their satisfaction and involvement of caregivers in medication management to strengthen geriatric healthcare system in Malaysia.