Adverse drug events of older patients presenting in the emergency department

The effect of medication is always a balance between their beneficial effects and any adverse reactions they might elicit. The main risk for adverse drug events (ADEs) is polypharmacy, which is the simultaneous use of multiple drugs. This often applies to older patients, who suffer from multiple diseases and therefore take multiple medications. Thus, it is not surprising, that ADEs are frequent in older patients and account up to 16 % of emergency visits. It is still under discussion, whether age is an independent risk factor for ADEs. However, there are some age-related changes in the pharmacokinetic and pharmacodynamic properties of many drugs, which may influence the highly fragile balance between benefit and harm in older patients. Though there are multiple risk factors for and causes of ADEs, it could be shown that a lot of ADEs are preventable and even predictable: Budnitz et al. showed that almost two thirds of emergency hospitalisations occur due to four medication classes: warfarin, oral antiplatelet agents, insulin and oral hypoglycaemic agents. Nevertheless, only 40 - 60 % of ADEs are recognized in the emergency department. This might be explained by the broad clinical symptoms, ranging from bleeding due to anticoagulants to the more nonspecific symptom of weakness due to hyponatraemia secondary to thiazide diuretics. Detecting and avoiding ADEs could be aided by using lists such as Beers criteria or STOPP/START which list medications which are potentially inappropriate for older patients.