Empirical Analysis of Medication Adherence Determinants in Elderly Patients with Chronic Non-Communicable Diseases in Lagos State

Elderly patients with multiple chronic non-communicable diseases constitute a rapidly growing population in Nigeria who are particularly susceptible to medication non-adherence due to cognitive, financial, and social vulnerabilities. This study empirically analysed the determinants of medication adherence in elderly patients with chronic NCDs at a geriatric outpatient clinic in Lagos, South West Nigeria. A cross-sectional analytical study was conducted among 200 patients aged 65 years and above with at least two chronic NCDs including hypertension, diabetes, and dyslipidaemia. Adherence was measured using the Morisky Medication Adherence Scale-8 and pill count verification. Multivariable logistic regression identified independent predictors of high adherence. Results showed high adherence in only 36.5 percent of participants. Polypharmacy above seven daily medications was a significant negative predictor of high adherence (OR 0.31; 95 percent CI 0.18 to 0.54; p < 0.001). Social support (OR 2.87; p < 0.001), pharmacist counselling within the preceding three months (OR 3.14; p < 0.001), and simplified once-daily regimen formulation (OR 2.52; p < 0.01) were significant positive predictors. Cognitive impairment was associated with a fourfold increase in non-adherence risk. Cost of medications was cited as a barrier by 58.5 percent of non-adherent patients. The study fills a gap in empirical adherence analysis for elderly multi-morbid patients in Lagos and provides quantified evidence for targeted pharmacist counselling, deprescribing interventions, and health insurance-supported drug cost reduction. Keywords: medication adherence, elderly patients, non-communicable diseases, Lagos State, polypharmacy