Structural analysis of causal pathways between adherence, satisfaction and clinical outcomes in hypertensive patients using a mobile adherence intervention: A SEM–NCA–cIPMA approach

Poor medication adherence remains a major barrier to effective hypertension control, particularly in low-resource settings. This study aimed to explore causal pathways, necessity conditions and optimization priorities of the CareAide mobile application for improving medication adherence and clinical outcomes among hypertensive patients. A prospective, randomised, open-label, two-arm trial was conducted at University Malaya Medical Centre. Adults (N = 275) with hypertension and low Morisky Medication Adherence Scale (MMAS-8) scores were randomised to CareAide plus usual care or usual care alone for six months. Primary outcome was adherence (MMAS-8) at third (F1) and sixth month (F2); secondary outcomes included systolic/diastolic blood pressure (Hypertension F1, F2) and application satisfaction via Mobile Adherence Satisfaction Scale (MASS). Structural Equation Modelling (SEM), Necessary Condition Analysis (NCA) and Combined Importance-Performance Map Analysis (cIPMA) tested hypotheses from an integrated theoretical framework. Intervention showed large positive effects on adherence at (F1 β = 0.58, F2 β = 0.79, P < 0.001). Six-month adherence mediated the intervention's impact on blood pressure (indirect β = -0.16, P = 0.006) and together with early adherence, formed a sequential mediation chain (β = -0.05, P = 0.01). NCA showed the intervention (d = 0.18) and early adherence (d = 0.28) were necessary for high F2 adherence; the intervention (CE-FDH = 100%) and prior blood pressure control (CE-FDH = 48.58%) were necessary for optimal F2 blood pressure. Feature satisfaction (FS) was both sufficient (β = 0.20, P < 0.001) and necessary (d = 0.29) for sustained adherence. cIPMA identified the intervention, early adherence and FS as high-importance, low-performance targets. CareAide significantly improves adherence and blood pressure via a temporally sequenced behavioral pathway with early adherence gains and FS are critical, actionable factors. Trial registration: CAREAide Trial (ClinicalTrials.gov identifier: NCT06068309).