The frequency of adverse drug reactions as dependent upon age, sex and duration of hospitalization.

In 1972, 171 (18, 7%) of 914 patients showed evidence of an adverse drug reaction (ADR) in a prospective study of the division of internal medicine in a regional teaching hospital (Zieglerspital, Bern). The following factors correlated positively with frequency of ADR: 1. The duration of hospital stay. 2. The age between 60 and 80 years. 3. Female sex. 4. Previous ADR. The fact that most of the ADR occur within the first three weeks of a hospital stay, combined with point 1, suggests early ADR having some predictive value for duration of hospital stay. Statistical data of type, severity, duration and pathogenesis of ADR are given. The drugs involved are mentioned.