Inappropriate drug use by Portuguese elderly outpatients - effect of the Beers criteria update

Objective To characterize the use of medicines and to evaluate the inappropriateness of drugs in elderly outpatient population. Setting Twelve community pharmacies in different districts of Lisbon - Portugal. Method Observational cross-sectional survey, in a sample of 213 elderly outpatients (age = 65-years-old) presenting a prescription with two or more drugs, for their own use. Main outcome measures Drug use pattern and prevalence of potentially inappropriate medication. Results We have studied 213 outpatients, who were taking a total of 1,543 drugs, with an average of 7.23 per patient. The drugs were distributed mainly in the following 3 ATC (Anatomical Therapeutic Chemical Classification) classes: C (cardiovascular system), N (nervous system) and A (alimentary tract). Using the 1997 Beers Explicit criteria, 75 occurrences of inappropriate medicines were detected in 59 patients (27.7%), while with the 2003 Beers Explicit criteria we detected 114 cases of inappropriate medication in 82 patients (38.5%). The occurrence of inappropriate medicines was significantly associated with the consumption of a high number of drugs. According to the ATC Classification, more than one half of the cases of inappropriateness were related with long acting benzodiazepines and with ticlopidine. The 2003 version detected a significantly higher prevalence of inappropriate drug use having potentially adverse outcomes of high severity. Conclusions The application of the updated Beers criteria lead to higher rates of potentially inappropriate medication, and especially those responsible for more severe adverse outcomes. The results suggest that there is a need for interventions to improve instructions for safe drug use in the elderly patients and to decrease the number of medications whenever it is possible. This study suggests a high prevalence of potentially inappropriate drug use by the elderly patients of Lisbon region, Portugal