Adverse drug reactions in older patients during hospitalisation: are they predictable?

Background: adverse drug reactions (ADRs) are a major cause of morbidity and healthcare utilisation in older people. The GerontoNet ADR risk score aims to identify older people at risk of ADRs during hospitalisation. We aimed to assess the clinical applicability of this score and identify other variables that predict ADRs in hospitalised older people. Methods: we prospectively studied 513 acutely ill patients aged >= 65 years. The GerontoNet ADR risk score was calculated for all patients. ADRs were identified through patient and physician consultation together with analysis of case notes. Receiver operator characteristic (ROC) curves were constructed to test the ability of the GerontoNet risk score to predict ADRs. Multivariate logistic regression examined the influence of individual variables on the presence of ADRs. Results: in-hospital ADRs were identified in 135 patients (26%). The area under the ROC curve was 0.62 (95% CI: 0.57-0.68). Variables which increased ADR risk include (i) renal failure (OR: 1.81, 95% CI: 1.12-2.92), (ii) increasing number of medications (OR: 1.09, 95% CI: 1.02-1.17) (iii) inappropriate medications (OR: 2.40, 95% CI: 1.26-4.50) and (iv) age >= 75 years (OR: 2.12, 95% CI: 1.23-3.70). Conclusion: the GerontoNet ADR risk score incorrectly classified 38% of patients as low risk. Inappropriate medications and increasing age also contribute to ADR risk.