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 antiinflammatory drugs and antidiabetic drugs were the most observed ADRs.

Background Adverse drug reactions (ADRs) constitute major clinical burden of public health concern. Intensive adverse drug reactions monitoring in hospitals, though advocated are rare. Aims Intensive monitoring of medical patients for ADRs to assess incidence, risk factors and fatality of ADRs leading to hospital admission or occurring in the hospital. Research design and methods Prospective cohort study on 1280 adult patients admitted to the six medical wards of a tertiary institution over a 12-month period. Patients were assessed for ADRs during and throughout admission. Causality assessment and preventability of ADRs were assessed. Results Sixty-seven (5.2%) patients had ADRs, which was the cause of admission in 46 (3.6%), and majority 61(91%) of the ADRs were preventable. NSAIDs, 14 (20.3%), antidiabetics, 12 (17.4%) and antibacterial, 11 (15.8%) were the most suspected drugs. Gastrointestinal tract (37%), CNS (30.2%), and skin (24.7%) were the most affected organ/systems, while upper GI bleeding and hypoglycaemia were the most observed ADRs. ADRs led to deaths in 7(10.4%) patients, with overall case fatality rate of 0.5%. Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis 3/7(42.9%) had the highest fatality rate. Risk factors, relative risk, 95% confidence interval for ADRs were alcohol intake, 1.7 (1.04, 2.80) and duration of hospital stay, 2.0 (1.16, 3.26). Conclusions Preventable ADRs are common and important cause of hospitalization and inpatients' morbidity and mortality among medical patients in Nigeria. Upper GI bleeding and hypoglycaemia, resulting from NSAIDs and antidiabetic drugs were the most observed ADRs. Strategic planning for intensive follow up of ADRs in Nigeria is advocated.