Adverse drug reactions leading to urgent hospital admission in an elderly population: prevalence and main features

To assess the prevalence of urgent hospitalization due to adverse drug reactions (ADRs) in patients aged a parts per thousand yen65 years, to compare the in-hospital mortality rates between patients admitted for ADRs and those admitted for other causes, and to describe the ADRs, the used and suspected drugs, and the drug-reaction associations. A cross-sectional study was conducted by using the institutional database of the Pharmacovigilance Programme of Bellvitge University Hospital, a 750-bed tertiary care hospital, with information corresponding to a 7-year period. ADR-related admissions of patients aged a parts per thousand yen65 years prospectively identified through a systematic daily review of all admission diagnosis were reviewed. ADRs were suspected to be the main reason for urgent admission in 1976 out of 60,263 patients aged a parts per thousand yen65 years (prevalence of ADR-related hospitalization 3.3 % [95 % CI 3.1-3.4 %]). The crude in-hospital mortality rate was 10.2 % in patients with ADR-related admission and 9 % in patients admitted for other causes (p = 0.077). Most patients (86 %) were exposed to polypharmacy, and a drug-drug interaction was suspected in 49 % of cases. The most frequent drug-reaction associations were acute renal failure related to renin-angiotensin system inhibitors, gastrointestinal bleeding caused by antithrombotics and/or non-steroidal anti-inflammatories, and intracranial bleeding induced by vitamin K antagonists. One out of every 30 urgent admissions of patients aged a parts per thousand yen65 years is ADR-related. These ADRs can be as serious and life-threatening as any other acute pathology that merits urgent hospital admission. Most cases involve patients exposed to polypharmacy and result from well-known reactions of a few commonly used drugs.