Cohort study on adverse drug reactions in adults admitted to the medical wards of a tertiary hospital in Nigeria: Prevalence, incidence, risk factors and fatality

Abstract

Aims: Intensive monitoring of medical patients for adverse drug reactions (ADRs) to assess prevalence, incidence, risk factors and fatality of ADRs leading to hospital admission or occurring in the hospital. Methods: Prospective cohort study on 1280 adult patients admitted to the medical wards of a tertiary institution over 12 months. Patients were assessed for ADRs during and throughout admission; causality and preventability of ADRs were assessed. Results: Sixty-seven (5.2%) patients had ADRs, 51 (3.9%) caused hospitalisation while 17(1.3%) occurred during hospitalisation, and 42 (62.7%) of total ADRs were preventable. Nonsteroidal anti-inflammatory drugs, 14 (20.3%), antidiabetics, 12 (17.4%) and antibacterial, 11 (15.8%) were the most implicated drug classes. Gastrointestinal tract (37%), central nervous system (30.2%), and skin (24.7%) were the most affected organ/systems, while upper gastrointestinal bleeding and hypoglycaemia were the most observed ADRs. ADRs led to deaths in 7 (10.4%) patients, with an overall case fatality rate of 0.5%. The highest number of deaths were among patients with Stevens–Johnson syndrome 2/7 (28.6%) and hepatotoxicity 2/7 (28.6%). Risk factors, adjusted odds ratio (AOR [95% confidence interval, CI]) for ADRs leading to hospitalisation was male sex 3.11 (1.11, 8.73) while for ADRs during hospitalisation were number of drugs used before admission (AOR [95% CI] = 6.67 [1.16, 38.47]) and comorbidities (AOR [95% CI] = 3.0 [1.13, 8.01]). Patients admitted with ADRs had prolonged hospital stay (AOR [95% CI] = 3.37 [1.11, 8.71]). Conclusion: Preventable ADRs are common and important causes of hospitalisation and inpatients' morbidity and mortality among medical patients in Nigeria. Upper gastrointestinal bleeding and hypoglycaemia, resulting from nonsteroidal anti-inflammatory drugs and antidiabetic drugs were the most observed ADRs.