Adverse events: past and future

The article by Alan Forster and associates1 on adverse events among patients admitted to a Canadian teaching hospital might suggest that this aspect of patient safety is of only recent interest and concern. However, CMAJ readers may be interested to learn of a study with similar findings that we published in CMAJ in 1967.2^,3 The methods used for the 2 studies differed, in that the earlier study used concurrent reporting and multiple means of detection (rather than a chart review) and was limited to a medical inpatient unit (rather than an entire hospital). We found that 24% of 731 patients had onset of an adverse event after admission to hospital, whereas the rate was 5% of 502 patients in the recent study. Reactions to drugs accounted for 62% of adverse events in the earlier study and 50% in the recent study, and nosocomial infections accounted for 9% and 19% of adverse events respectively. The latter difference may be explained by the inclusion of surgical patients in the recent study. Both studies concluded that most of the adverse drug events were preventable (81% and 67% respectively).

Identifying adverse events is an important step in prevention. Our recognition of overdose with digoxin2^,3 led to an educational approach that resulted in an important reduction in the incidence of those events.4

John Ruedy Professor (Emeritus) of Pharmacology Dalhousie University Halifax, NS Richard I. Ogilvie Professor (Emeritus) of Pharmacology and Medicine University of Toronto Toronto, Ont.