Prevalência de Reações Adversas a Medicamentos em um Hospital de Nível III no Sudoeste da Colômbia em 2024

Introduction: Adverse drug reactions (ADRs) constitute a patient safety problem with a significant clinical and economic impact; they affect up to 10% of hospitalized patients, and more than 90% go unreported. This study aims to determine the prevalence of ADRs in hospitalized patients using the tracer drug methodology during 2024 at a clinic in southwestern Colombia. Methodology: This retrospective cross-sectional study analyzed the records of patients hospitalized during 2024 at a level III clinic in southwestern Colombia who were prescribed one of the defined tracer drugs (hydrocortisone, clemastine, hydroxyzine, protamine, neostigmine, vitamin K, flumazenil, or naloxone). Data from patients over 18 years of age were included, and cases with insufficient information or a diagnosis of sepsis requiring corticosteroid use were excluded. The variables included sociodemographic characteristics, medication type, and the presence and characteristics of adverse drug reactions (ADRs) (type, severity, and causality). Severity was classified as mild, moderate, or severe, and causality was assessed using the Naranjo algorithm. Data were analyzed using RStudio. Results: 403 patient records were analyzed (59.8% women, median age 57 years). The majority were hospitalized in general wards (75.6%) with a median length of stay of 5 days. The most frequently prescribed tracer medications were hydrocortisone (37.9%) and hydroxyzine (36.8%). The overall prevalence of ADRs was 8.81% (95% CI: 6.53–11.77). Reactions were observed primarily with clemastine (17.2%), hydrocortisone (9.9%), and hydroxyzine (6.6%). Moderate reactions (52.5%) and type B reactions (48.7%) predominated, followed by type A reactions (41%). Regarding causality, 35.9% were proven or defined, and 33.3% were probable. No significant differences were found in severity by medication (p=0.61), but significant differences were found in causality (p=0.01). Conclusions: The observed prevalence falls within the ranges reported nationally and internationally. The tracer drug methodology proved effective in identifying clinically relevant ADRs, even in contexts of underreporting. These findings support the implementation of active surveillance strategies, staff training, and the use of clinical alerts to promote the rational and safe use of medications in Colombian hospital settings.