Incidence of lethal adverse drug reactions in the comprehensive hospital drug monitoring, a 20-year survey, 1974-1993, based on the data of Berne/St. Gallen

Realising the limitations of spontaneous drug monitoring systems concerning the epidemiological aspects, a comprehensive program was founded. It was based on previous publications from the US, Canada and Northern Ireland, mainly those of the BCDSP (Boston Collaborative Drug Surveillance Programme). Drug monitoring was carried out by a group of physicians which included the medical head of each of the divisions of internal medicine, a statistician and an informatician. Only probable or definite drug event relationships were included. A probable event is defined as one in which the drug interaction was more likely to be the cause than any non-drug-related cause. The same criteria were valid for the lethal reactions. In the present evaluation, we found 26 probable lethal adverse drug reactions out of a total of 48,005 patients consecutively admitted to the divisions of internal medicine of three Swiss teaching hospitals during the years 1974-1993, an incidence of 0.054%. The median age of the cohort was 68 years (range 11-103 years), of which 49% were women. The median hospital stay was 14 days and the median number of drugs was eight per patient. The patients with a lethal outcome were presented under the eight pharmacologic-therapeutic classes of drugs and the classification proposed by NS Irey. This is based on long histopathologic experience and helps to identify preventable risks.