BACKGROUND: The lack of information on serious adverse drug-related events (ADEs) among outpatients in Japan makes it difficult to assess the preventability of such events and develop strategies to prevent their occurrence or to ameliorate them. We therefore examined the frequency, severity, consequences of serious ADEs and the causative drugs used in the critical care setting.

METHODS: A standard case data form and questionnaire regarding ADEs were mailed to critical care departments (CCDs) of hospitals in Japan. Demographic data and information regarding the diagnoses, causative drugs, treatments, and outcome, etc., were entered into an electronic database.

RESULTS: Between January and December 2008, 66,983 patients were admitted to 39 CCDs (17.9% of all CCDs) in Japan. Of them, 363 cases were attributable to ADEs. The common ADEs were hypoglycemia, followed by hemorrhage, allergic reaction, and cardiac arrhythmia. The major causative drugs were insulin, aspirin, warfarin, glibenclamide, glimepiride, ticlopidine, and diclofenac. Almost all these causative drugs were prescribed by physicians and dispensed by pharmacists.

CONCLUSIONS: To decrease serious ADEs, physicians and pharmacists should target these prescription drugs and monitor the course of treatment with these drugs to provide accurate and complete instructions for treatment in outpatients more appropriately.