Case-control study of exposure to medication and the risk of injurious falls requiring hospitalization among nursing home residents.

The association between injurious falls requiring hospitalization and selected classes of medications was examined in a case-control study of nursing home residents. Information for this study was obtained exclusively from four computerized administrative databases. Over the period from April 1987 to March 1992, a total of 1,560 first injurious falls occurred to 14,744 residents of Manitoba, Canada, nursing homes who were eligible for inclusion in the study. An injurious fall was defined as an injury consequent to a fall that resulted in admission to the hospital for treatment. Medication use was ascertained from prescription information contained in computerized dispensing records from community pharmacies. Three series of single controls were pair-matched to each case, implementing increasing stringent matching on age, sex, level of dependency, duration of residence, and the presence of up to five chronic disorders. Estimates of relative odds obtained from the most stringently matched case-control series identified two medication classes in which a prescription dispensed in the previous 30 days was associated with an elevated risk of injurious fall: antipsychotic agents (odds ratio = 1.31, 95 percent confidence interval 1.06-1.61) and anxiolytics/sedatives/ hypnotics (odds ratio = 1.35, 95 percent confidence interval 1.09-1.68). An unexpected protective effect was associated with the use inotropic agents (odds ratio = 0.69, 95 percent confidence interval 0.54-0.89). These results support the hypothesis that psychotropic medications are an independent risk factor for injurious falls in nursing home settings.