Life-threatening adverse drug reactions at admission to medical intensive care : a prospective study in a teaching hospital

To assess the characteristics of life-threatening adverse drug reactions in patients admitted to medical intensive care unit and to define those that could facilitate early identification. A prospective 6-month observational study. Of the 436 admissions to the teaching hospital medical intensive care unit, all patients aged over 15 years and who had received documented drug treatment were included (n = 405). Characteristics of patients [age, gender, underlying diseases, organ failure(s), drugs taken, Severity Acute Physiologic Score II, length of stay, outcome at discharge] were prospectively collected using a standardised questionnaire. A panel of experts assessed putative serious adverse drug reaction(s) for each drug taken and each organ failure at admission by using a standardised causality assessment method. Characteristics of patients with and without serious adverse drug reactions at admission were compared using univariate and then stepwise descending multivariate logistic regression. Of the 405 patients included, 111 (27.4%) presented an adverse drug reaction leading to organ failure. In 48% of cases adverse drug reactions were preventable, 23% were undiagnosed and 19% contributed to death. Age over 75 years [odds ratio (OR) 2.25; 95% confidence interval (CI) 1.15-4.38; p = 0.02], having more than three drugs (OR 6.90; 95% CI 1.44-33.00; p = 0.02) and a diagnosis of haematological malignancy (OR 6.19; 95% CI 2.07-18.53; p = 0.001) were independently associated with serious adverse drug reactions. Preventable life-threatening adverse drug reactions were frequently involved in organ failure at admission to medical intensive care; many of them had not been identified.