Assessment of Adverse Drug Reactions due to Antimicrobial Drugs in Medicine Inpatients at a Tertiary Care Public Teaching Hospital

Background: Adverse drug reactions (ADRs) represent the risk associated with the anticipated benefits of drug therapy and are known to be leading cause of morbidity and mortality worldwide. ADRs constitute an enormous clinical and economic burden on health care system. Objectives: The objectives of this study were to identify the ADRs and to assess their causality, severity and preventability. Methodology: This prospective observational study was conducted in the patients admitted to medicine wards of a public teaching hospital. Patients of all age groups and either sex admitted in medicine wards were included in this study. The ADRs were identified based on subjective and objective markers. The causality of suspected ADRs was assessed using Naranjo’s ADR probability scale and WHO-UMC causality scale. Severity and preventability were assessed using modified Hartwig’s severity scale and modified Schumock & Thornton criteria, respectively. Results: Over the study period, data from 808 patients was collected. Of which 776 were analysed as they met the inclusion criteria. Out of 776 patients with complete documentation, 77 patients developed 82 ADRs during their stay in hospital with an incidence of 9.9%. The highest number of ADRs were associated with antimicrobial drugs (AMDs) (24.4%) followed by diuretics (15.9%) and opioid analgesics (14.6%). Overall 19 patients suffered adverse drug reactions due to administration of AMDs and a total of 20 ADRs were observed. Beta lactam AMDs were most frequently associated with ADRs. Among the organ systems affected, half of the ADRs due to AMDs were associated with GIT followed by cutaneous (40%). Hypersensitivity reactions (40%) were most commonly observed ADRs due to antimicrobial drugs. Based on Naranjo’s scale 10% of ADRs were ‘definite’, 50% were ‘probable’ and 10% were ‘possible’ in nature. Further, based on WHO-UMC scale 20% of ADRs were ‘certain’, 30% were ‘probable’ and 50% were ‘possible’. Modified Hartwig’s severity scale showed 20% of ADRs were ‘mild’ and 80% were ‘moderate’. Preventability assessment showed that 40% were ‘probably preventable’ and 60% were ‘not preventable’. Also 60% of the ADRs were Type A in nature while remaining 40% were Type-B in nature.