Incidence of Adverse Drug Reactions at the University Hospital Center of Libreville, Gabon: From Data Collection to a Risk Minimization Plan

Background: According to the literature, adverse drug reactions (ADRs) account for 5–10% of hospital admissions and affect 25–30% of hospitalized patients, but no data are available for Gabon. Objectives: To estimate the incidence of ADRs among hospitalized patients at the Libreville University Hospital Center (CHUL) and to classify them according to their frequency, severity, mechanism and preventability, while proposing appropriate risk minimization strategies. Patients and Methods: A 14-month, single-center, prospective study included all patients experiencing ADRs, excluding those without ADRs or with intentional overdoses. ADRs were analyzed using the World Health Organization (WHO) causality assessment, the ATC classification, and Rawlins and Thompson criteria. Data were actively collected from patients and hospital records. Results: Among 4999 patients, 105 experienced 177 adverse events (incidence: 3.5%, 95% CI: 1.7–2.5%). Among the identified ADRs, 42% were serious. Nausea and vomiting were the most frequent ADRs, mainly caused by analgesics (nefopam, tramadol) and antibiotics (amoxicillin–clavulanic acid). The gastrointestinal and nervous systems were the most affected. According to the Rawlins and Thompson classification, 90% of ADRs were type A, 8% type B, and 2% type E (withdrawal syndrome). Overall, 90% of ADRs were preventable. Conclusions: This study highlights the importance of pharmacovigilance at CHUL, Gabon, and emphasizes the role of healthcare professionals in ADR reporting and risk minimization.