[Adverse internal medicine drug effects at hospital admission].

Hospital admissions due to adverse drug reactions are an important concern, but there are few data concerning the specific situation in Switzerland. During one year we therefore prospectively studied all admissions to our medical department to determine the profile. 138 of 2168 patients presented a total of 150 adverse drug reactions at hospitalisation (6.4%) and among them 65% of the admissions were directly related to adverse drug reaction. Age stratification revealed that with each decade of age there was an increasing risk of adverse drug reactions and that the patients were sicker (more diagnoses), were consuming more drugs and had longer stays. The majority of adverse drug reactions were type A reactions and therefore potentially preventable. Cardio- and cerebrovascular drugs (diuretics, ACE-inhibitors, platelet aggregation inhibiting therapy) accounted for 65% of the side effects. Analysed by affected organ system, the most frequent adverse drug reactions were gastrointestinal complications followed by dehydration (contracted extracellular fluid volume) and hypo-/hyperkalaemia. Non-compliance by the patients was less frequently at the origin of the admission than iatrogenic causes related to physician errors. The patients generally did not know the reasons, details and side effects of their medical treatment. Based on our data, we estimate that the national number of drug-related hospital admissions caused by inappropriate or unnecessary treatment is 12,000-16,000, with direct annual extra costs of 70-100 million Swiss francs. Adverse drug reactions therefore represent a serious medical and financial problem. Specialised computing systems designed to reduce these events should be introduced in hospitals and ambulatory care.