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

Objective: 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.

Design: A prospective 6-month observational study.

Patients: 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).

Measurements: 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.

Results: 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.

Conclusions: 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.