Introduction
Medical treatment represents the most commonly used treatment modalities in the world but adverse drug reactions (ADRs) from their usage pose a great limitation. Adverse drug reactions (ADRs) are an important cause of hospital admission, morbidity and mortality in hospitalised patients [1]. Prevalence of ADR-related hospitalisations in developed and developing countries reported as 6.3 % (3.3-11.0) and 5.5 % (1.1-16.9), respectively, and the majority of the ADRs are preventable [2]. ADRs have been reported as a significant cause of deaths among hospitalised patients. The economic burden resulting from adverse drug reactions among hospitalised patients is enormous, requiring between billion United State Dollars ($30 billion) annually in the US [4].
In the Western world, the incidence of adverse reaction reactions varies between 3.5% and 19.2% [5,6], while the incidence of 5.5% was reported in Saudi Arabia [7]. In South Africa, the incidence of ADRs was reported as 6.3% [8]. Adverse drug reactions studies in Nigeria are rare and where available are retrospective [9], or from randomized controlled clinical trials [10,11]. Adverse drug reaction rates vary depending on the methods of ADRs detection employed in different studies. Medical record review in conjunction with patient interview yield higher ADR admission rates compared with medical record review alone.
Adverse drug reactions reporting through pharmacovigilance have been difficult in Nigeria and most studies have reported a low rate of reporting [12-15]. Particularly, intense follow up of patients in order to assess any adverse reaction occurring during the hospital stay is rare. Our literature search did not reveal and to our knowledge this is the first prospective cohort studies on adverse drug reactions in in-patients spanning a period of one year in Nigeria. Aim of the study is an intensive monitoring of medical patients for ADRs to assess prevalence, incidence, risk factors, preventability and fatality of ADRs leading to hospital admission or occurring in the hospital.