Contribution of adverse drug reactions to hospital admission of older patients.

Objective: To describe the severity of adverse drug reactions as a factor in hospital admission of older patients, and to identify risk indicators for severe adverse drug reactions in these patients.

Design: Observational cross-sectional study.

Setting: Five wards in a university hospital in The Netherlands.

Subjects: Patients aged 70 and over admitted to general medical wards.

Methods: Use of statistical comparison and Kramer's algorithm.

Results: A severe adverse drug reaction was present in 25 (24%) of 106 patients. Thirteen patients (12%; 95% confidence interval 6.1-18.6%) were admitted probably because of an adverse drug reaction. Risk indicators for a severe adverse drug reaction were a fall before admission (odds ratio 51.3, P = 0.006), gastrointestinal bleeding or haematuria (odds ratio 19.8, P < 0.001) and the use of three or more drugs (odds ratio 9.8, P = 0.04).

Conclusion: Adverse drug reactions are an important cause of hospital admissions in older people. A fall before admission may indicate a severe adverse drug reaction.