Hospitalizations because of adverse drug reactions in elderly patients admitted through the emergency department: a prospective survey.

Background And Objectives: Several studies have been conducted to determine the frequency and characteristics of adverse drug reactions (ADRs) in elderly populations, focusing on those leading to hospital admission. However, most of these studies have been limited in their ability to assess risk factors, particularly the renal status of patients. Thus, the aim of this prospective study was to assess the incidence of ADRs and associated factors leading to hospital admissions in the elderly population.

Methods: All patients aged > or =65 years admitted to the Toulouse University Hospital through the Emergency Department during four non-consecutive weeks in 2002-3 were included in this study except for patients in ambulatory care or admitted for intentional overdoses. The characteristics of patients admitted for a suspected ADR were compared with those of patients admitted for other reasons.

Results: The incidence of hospital admissions for ADRs was 8.37 per 100 admissions (95% CI 6.52, 10.52), corresponding to 66 patients with ADRs among 789 admissions. The most important factors associated with ADRs were the number of drugs being taken (odds ratio [OR] 1.18; 95% CI 1.08, 1.29), self-medication (OR 2.34; 95% CI 1.18, 4.66), use of antithrombotics (Anatomic Therapeutic and Chemical [ATC] classification B01; OR 2.26; 95% CI 1.33, 3.88) and use of antibacterial drugs (ATC J01; OR 4.04; 95% CI 1.50, 10.83). Surprisingly, exposure to drugs for acid-related disorders was associated with a low risk of ADRs (OR 0.26; 95% CI 0.09, 0.76).

Conclusion: A significant incidence of ADRs leading to hospital admissions was found among elderly people. Our study showed that there is a need to increase the availability of information for the general public concerning potential ADRs due to self-medication and for prescribers concerning ADRs due to drug-drug interactions and polypharmacy.