Adverse drug events in surgical patients: an observational multicentre study

Background Errors occurring during different steps of the medication process can lead to adverse drug events (ADEs). Surgical patients are expected to have an increased risk for ADEs during hospitalization. However, detailed information about ADEs in the surgical patient is lacking. Objective In this study, we aim to measure the incidence and nature of (preventable) ADEs, potential risk factors for and outcome parameters of (preventable) ADEs in surgical patients. Setting Observational multicentre cohort study in which eight surgical wards participated from three Dutch hospitals, all using computerized physician order entry (CPOE) systems with clinical decision support. Methods Electively admitted surgical patients of the participating wards were included from March until June 2009. ADEs were measured using a standardized method with expert judgment. Incidence, severity, preventability and accountable medication were assessed. Poisson regression analysis was applied to determine the associations between possible risk factors and the occurrence of ADEs, expressed as incidence rate ratio (IRR). Also outcomes of ADEs in surgical patients were measured. Main outcome measure The incidence and nature of (preventable) ADEs in surgical patients. Results A total of 567 surgical patients were included. We found an incidence of 27.5 ADEs and 4.2 preventable ADEs (pADEs) per 100 admissions (15.4 %). A quarter of the pADEs were severe or life-threatening. Opioids and anti-coagulation medication play a major role in the occurrence of ADEs and pADEs respectively. Univariate analysis revealed an American Society of Anesthesiologists classification of III or more as a risk factor for ADEs. Patients older than 65 years [IRR 2.77 (1.14–6.72)], with cardiovascular comorbidity [IRR 2.87 (1.13–7.28)], or undergoing vascular surgery [IRR 2.32 (1.01–5.32)] were at risk for pADEs. Patients experiencing an ADE had a significant longer duration of admission than patients without an ADE. Conclusions Surgical patients are at considerable risk of experiencing one or more ADEs during their admission, also in CPOE-hospitals. Risk factors for pADEs are age older than 65 years, cardiovascular comorbidity, and vascular surgery. Intensified monitoring may be needed in patients with a higher than average risk for pADEs.