Guideline-directed statin therapy and cardiovascular events among patients with type 2 diabetes mellitus in South Ethiopia: a case-control study

Type 2 diabetes mellitus (T2DM) significantly increases cardiovascular disease (CVD) risk. Statin therapy is a cornerstone of primary prevention, yet suboptimal prescribing and adherence remain common, particularly in resource-limited settings. Evidence on statin utilization and outcomes in Ethiopian T2DM patients is limited. This study aimed to determine the association between guideline-directed statin therapy and cardiovascular events among T2DM patients at Wolaita Sodo University Comprehensive Specialized Hospital (WSUCSH). A hospital-based case-control study was conducted from April to July 2022 at WSUCSH in South Ethiopia. Cases were T2DM patients aged 40-75 years who developed a first cardiovascular event after T2DM diagnosis. Controls were T2DM patients without CVD, frequency-matched by age (±5 years) and sex. Data were collected through retrospective medical record review and patient interviews using a structured data abstraction form and the Morisky Medication Adherence Scale. Unconditional logistic regression was used to estimate adjusted odds ratios (AOR) with 95% confidence intervals (CI), with age and sex included as covariates to account for the frequency-matched design. A p-value <0.05 was considered statistically significant. A total of 196 participants (98 cases and 98 controls) were included. Among cases, stroke (43.9%) and myocardial infarction (35.7%) were the most frequent cardiovascular events. Patients receiving guideline-directed statin therapy had significantly lower odds of CVD events [AOR=0.242, 95% CI: 0.093-0.630, p=0.004]. However, only 13.8% received guideline-concordant therapy, and annual lipid testing was documented in only 4.6%. In this case-control study, guideline-directed statin therapy was associated with lower odds of cardiovascular events among T2DM patients in South Ethiopia. However, the majority of participants did not receive guideline-concordant therapy, highlighting a substantial practice gap. Interventions to improve statin prescribing, adherence, and continuity are urgently needed in this setting.