Objective It has been shown that pharmacists, as members of multidisciplinary patient care teams, can decrease the number of medicine errors. The objective of the present study was to analyse pharmaceutical interventions (PI) in emergency departments, to assess their clinical relevance, the cost-effectiveness and the potential economic benefits.

Methods We designed a 5-month observational prospective study of PI in the emergency department (ED) of a 330-bed hospital in Spain. We analysed PI made by a pharmacist during a period of 3 hours a day from Monday to Friday in the ED, and classified detected medication errors according to their relevance and severity using the National Coordinating Council for Medication Error Reporting and Prevention (NCC MERP) severity index, and whether or not the drug involved was on the High-Alert Medications Institute for Safe Medication Practices (ISMP) list. We used statistical analysis to study the relationship between the relevance of PI and age, gender, the number of interventions per patient, and whether or not the drug was on the High-Alert Medications ISMP list. We also estimated the incremental cost incurred for each PI (cost-effectiveness) and the potential economic benefits (cost-benefit).

Results A total of 529 interventions for 390 patients (median age 72.7±8.6 years, 53.1% women) were performed during the study period, representing 1.4 interventions per patient with an acceptance rate of 84.9%. Of all potential medication errors, 112 (21.2%) were related to drugs on the High-Alert Medications ISMP list, and using the NCC MERP severity index, we found that 150 (28.3%) of those errors could cause harm. We also found a relationship between patients on high-risk medications according to the ISMP and the relevance of PI. Finally, this study showed an incremental cost for each PI of 20.23 Euros and a cost-benefit ratio of 3.46 Euros per intervention.

Conclusion These results show that clinical pharmacist can positively identify and reduce medication errors and costs associated, considering the number of interventions observed and those of clinical relevance. Based on these results, drug safety therapy in the ED can be improved by the revision of prescriptions by a clinical pharmacist.