Hospitalisation and morbidity due to adverse drug reactions in elderly patients: a single-centre study.

BACKGROUND: Adverse drug reaction (ADR) is a leading but under-recognised cause of illness, particularly in frail subjects with multiple comorbidities. AIM: To investigate the frequency, patterns and outcomes of ADR as a cause of hospitalisation in elderly patients admitted to an internal medicine ward. METHODS: We performed a retrospective observational study including every patient aged over 65 years who was admitted to our department during a 12-month period. Patients admitted to short-stay (<24 h) observation unit were excluded. RESULTS: ADR accounted for 106 of total 1750 recorded admissions, which constituted a proportion of 6.1% (95% confidence interval 5.0-7.3%). The median age of patients was 83.5 (78.0-87.0) years and 56.6% were on polypharmacy. A total of 170 ADR was recorded with 45.3% of subjects experiencing concomitantly more than one ADR from a single molecule. Diuretics were the most commonly imputed molecules (30 events, 17.6%), followed by antithrombotics (25 events, 14.7%) and central nervous system-active drugs (16 events, 9.4%). Interactions were judged responsible for 39 cases of ADR (36.8%). An unfavourable outcome was observed in about one-third of patients (37.7%). Among those subjects, 11 (10.4%) died and 29 (27.4%) had residual disability. CONCLUSION: ADR are a common cause of hospital admission in elderly patients and are often associated with adverse outcomes. Our data underline the need of appropriate strategies aimed at identifying high-risk patients and avoiding potentially preventable drug toxicities.