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.

Objectives: 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).

Methods: 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.

Results: 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.

Conclusion: 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.