Unmet needs and polypharmacy as key drivers of drug therapy problems among cardiac patients at a tertiary hospital: a cross-sectional study

Drug therapy problems (DTPs), unintended events in pharmacotherapy that impede therapeutic goals and risk patient harm, are critical barriers to effective cardiovascular disease (CVD) management. Ambulatory cardiac patients are highly vulnerable to DTPs primarily due to complex comorbidities, but the prevalence and specific drivers of these problems within chronic care settings in Ethiopia are poorly characterized. Therefore, this study aimed to determine the prevalence and predictors of DTPs among adult ambulatory CVD patients at Wolaita Sodo University Comprehensive Specialized Hospital from May 9 to July 8, 2022. We conducted an institution-based cross-sectional study among ambulatory cardiac patients receiving chronic care. Data were collected through structured patient interviews and comprehensive medical record reviews. DTPs were systematically identified and classified using Cipolle's validated methodology, adapted for the local patient population. Binary logistic regression was used to assess the associations between predictor variables and DTPs, followed by multiple logistic regression to control for potential confounders. Statistical significance was determined at p≤0.05, with 95% confidence intervals used to estimate precision of effect measures. Among 195 ambulatory CVD patients, hypertension (59.5%, n=116) and heart failure (47.2%, n=92) were the most prevalent conditions. The study identified DTPs in 69.7% of patients (n=136), totaling 168 DTPs (mean: 1.3, standard deviation: 0.461) per affected patient. Unmet therapeutic needs (41.0%) and medication non-adherence (24.4%) emerged as the most common DTP categories. ASCVD risk assessment classified 40% of evaluated patients as high-risk (10-year risk ≥20%). Significant predictors of DTPs included polypharmacy [adjusted odds ratio (AOR): 3.48, 95% confidence interval: 1.47-8.24] and age (25-64 years: AOR=16.38), while prior hospitalization (AOR: 0.31) demonstrated protective effects. This study identifies unmet therapeutic needs and medication non-adherence as the predominant DTPs and polypharmacy as the most significant predictor among ambulatory CVD patients at Wolaita Sodo University Comprehensive Specialized Hospital, calling for systematic medication reviews, pharmacist-led interventions for high-risk groups, and enhanced adherence support programs to optimize treatment outcomes.