DRUG INTERACTIONS AND ADVERSE DRUG REACTIONS IN THE OLDER PATIENTS ADMITTED TO THE EMERGENCY DEPARTMENT

Purpose: The aim of this study was to prospectively evaluate drug interactions and adverse drug reactions (ADRs) in the older patients admitted to the emergency department (ED) and to characterize risk factors. Methods: In 80 patients aged 65 years and older medication history and ED drug administration were-analysed. Medical records were analysed for ADRs by an expert panel which also evaluated their avoidability and causality. An interaction program was used to search for potential drug interactions followed by assessment for clinical significance. Data were analysed using a logistic regression model. The significance level was set at alpha=0.05. Results: Eighty seven ADRs were identified in 37 patients; 18 were the result of an interaction (15 patients). Causality was assessed as definite (n = 1 ), probable (n = 62) and possible (n = 24). The reason for admission was definitely and probably related to an ADR in 6 and 18 patients respectively. Only 17 (20%) of the ADRs were assessed as unavoidable, while 23 (26%) and 47 (54%) were classified as definitely and possibly avoidable, respectively. ADRs were related with female gender (p = 0.023) and number of drugs (p = 0.004), but not with high age, (p = 0.151.). Clinically relevant interactions were related with older age (p = 0.032) and number of drugs (p = 0.003), but not with gender (p = 0.380). None of the interactions with ED initiated medications were considered unjustified. Conclusions: ADRs frequently occur in the older patients admitted to the ED and are an important cause of hospital admissions with a substantial contribution of adverse drug interactions.