The Incidence of Serious Adverse Drug Reactions in Critical Care and their Reporting Rate: a Prospective Study

Andrew Hitchings1,2. 1Royal Free London NHS Foundation Trust, London, UK, 2St George's, University of London, London, UK

BACKGROUND: Adverse drug reactions (ADRs) are a major cause of morbidity and mortality, and are often avoidable. Spontaneous reporting of these reactions may play an important role in safeguarding public health. Critically ill patients are at particular risk of ADRs due to the intensity of drug treatment they require, and the presence of physiological disturbances that may increase their susceptibility to adverse reactions.

AIMS: To characterise the incidence and nature of serious adverse drug reactions in a critical care setting, and to audit their reporting to the medicines regulator via the Yellow Card scheme.

METHOD: A single investigator prospectively reviewed the case histories of adult patients admitted to the critical care units of a London teaching hospital over a 3-month period. A convenience sampling method was used. Where ADRs were identified, they were classified by severity; whether they caused or complicated critical illness; and whether or not they were potentially avoidable. Enquiries were made of the clinical staff involved to ascertain whether the reaction had triggered a Yellow Card report.

RESULTS: Between 1 January and 31 March 2012, 358 patients were admitted to the adult critical care units of this hospital, of whom 143 (40%) were included in the study. 1026 patient-days of ICU care were reviewed. The patients included had a median age of 61 years; 89 (62%) were male; and 89 (62%) were admitted non-electively. Serious ADRs were detected in 9 cases (6.3%), equating to a rate of 8.8 events per 1000 patient-days. In 6 cases, the ADR was the main reason for ICU admission (4.2% of all admissions, or 6.7% of non-elective admissions). Eight of the ADRs (89%) were classified as life-threatening (death occurred in 1 case), and 4 (44%) to have been potentially avoidable. None of the events had been reported through the Yellow Card scheme prior to their identification in this study.

CONCLUSION: This study supports the view that adverse drug reactions are an important cause of potentially avoidable morbidity and mortality among critically ill patients. In common with other settings, underreporting of ADRs in critical care is prevalent.