Prospective Evaluation of Adverse Drug Reactions in Hospitalized Older Adults in Ethiopia

Background: Older adults are vulnerable to adverse drug reactions (ADRs), particularly in low-income settings, yet data on ADR prevalence in Africa, including Ethiopia, remain limited. Objective: This study aimed to evaluate the incidence, severity, and preventability of ADRs among hospitalized older adults, as well as all-cause inpatient mortality. Methods: A cross-sectional observational study was conducted at Jimma Medical Center, located in Jimma town, Ethiopia, from 6 September 2021 to 26 December 2022. The study participants were older adults (N = 162) admitted to the medical wards. ADRs were assessed using the Naranjo ADR probability scale, severity was classified according to the modified Hartwig and Siegel criteria, and preventability was determined using the Schumock and Thornton criteria. Results: The median age of participants was 65 years (interquartile range: 60–70). During their hospital stay, 84 patients (51.9%) experienced at least one ADR. A total of 123 ADRs (76 ADRs per 100 admissions) were captured. Most ADRs (93.5%) were classified as mild to moderate in severity, and 84.5% (n = 105) were considered preventable. Endocrine and metabolic systems (48.8%) and diuretics (43.9%) were the most frequently affected organ systems and drug class linked to ADRs, respectively. Furosemide (41.5%) and aspirin (10.6%) were the most frequently implicated medications, commonly causing hypokalemia (35.3%) and dyspepsia (53.8%), respectively. The observed all-cause in-patient mortality rate was 6.8% (5 deaths per 1000 patient-days). The use of potentially inappropriate medications (PIMs) (aOR: 4.747, p = 0.003) and presence of digestive system disorders (aOR: 8.784, p = 0.038) were associated with an increased risk of ADRs, while a history of recent traditional medicine use (aOR: 0.285, p = 0.042) was linked to a lower risk. Conclusions: More than half of the hospitalized older adults experienced ADRs, most of which were mild to moderate in severity and considered preventable. Regular medication review for screening and minimizing PIM use in older adults may play a crucial role in lowering ADR occurrence. The borderline but statistically significant association between a history of traditional medicine use and lower occurrence of ADRs requires cautious interpretation and further investigation to explore possible explanations. Nearly seven deaths per hundred hospitalized patients were recorded.