Background An emergency department (ED) is a dedicated area in a hospital that provides continuous access to emergency medicine services for undifferentiated, urgent presentations across the entire spectrum of medical, surgical, trauma and behavioural conditions. An adverse drug event (ADE) has been defined as ‘any harm associated with any dose of a drug’. A preventable ADE is ‘harm caused by the use of a drug as a result of an error’.

Purpose Clinical pharmacists can play an important part in the identification and reduction of preventable ADEs in the ED. This study evaluated the type and frequency of a clinical pharmacist’s interventions and their effect on preventable ADEs and their cost implications in the ED of an Irish teaching hospital.

Material and methods The study was a cross sectional observational study of all clinical pharmacist interventions completed on ED lodged (inpatient) adult (≥16 years old) prescriptions over 22 consecutive working days. The Pharmaceutical Care Network Europe 2010 classification system for drug related problems and the National Coordinating Council for Medication Error Reporting and Prevention Index for Categorising Medication Errors were used to categorise interventions. Cost benefit analysis was also performed through the Nesbit method using probability scoring of patient drug harm in the absence of pharmacist intervention.

Results 92 patients required no ED pharmacist intervention and 169 patients required at least one intervention. 289 interventions were completed on 169 patients with a prescriber acceptance rate of 61.9%. The predominant intervention type was omission of regular medication on admission (36%). 65.1% of ED pharmacist interventions were categorised as a potential ADE and 3.5% were categorised as actual ADEs by two ED consultants. Comparatively, the ED pharmacist categorised 67% of interventions as a potential ADE and 11.4% as actual ADEs. A cost benefit of €20 876 and a cost benefit ratio of 3.76:1 was associated with the ED pharmacist service through the avoidance of ADE costs in the study.

Conclusion An ED clinical pharmacist service has demonstrated a positive impact on identification and reduction of preventable ADEs. This reduction in patient drug harm corresponds to a cost avoidance in excess of three times the cost of the pharmacist service.

No conflict of interest