Optimizing pharmacists' detection of prescribing errors: Comparison of on-ward and central pharmacy services

Prescribing errors are the leading cause of adverse drug events in hospitalized patients. Pharmaceutical validation, defined as the review of drug orders by a pharmacist, associated with clinical decision support (CDS) systems, significantly reduces these errors and adverse drug events. In Belgium, because clinical pharmacy services have limited public financial support, most pharmaceutical validations are performed at the central pharmacy instead of on-ward, by hospital pharmacists doing dispensing activities. In that context, we aimed at evaluating whether the strategy of CDS-guided central validation was the most appropriate method to improve the quality and safety of medicines' use compared to an on-ward pharmaceutical validation.

Our retrospective observational study was conducted in a Belgian tertiary care hospital, in 2018-2019. Data were extracted from our validation software and pharmacists' charts. The outcomes of the study were the number of pharmaceutical interventions due to the detection of prescribing errors, reasons for interventions, their acceptance rate and their potential clinical impact (according to two blinded experts) in the central pharmacy and on-ward validation groups.

Despite the use of the same CDS, a pharmaceutical intervention following the detection of a prescribing error was made for 2.9% (20/698) of central group patients and 13.3% (93/701) of on-ward patients (χ²  = 49.97, p < 0.001). Interventions made at the central pharmacy (n = 20) mostly relied on CDS-alerts (i.e. drug-drug interaction [25%] or overdosing [20%]) while interventions made on-ward (n = 93) were also for pharmacotherapy optimization (i.e. no valid indication [25%] or inappropriate drug's choice [11%]). The on-ward validation group showed a higher acceptance rate compared to the central group (84% and 65%, respectively [Fisher's test, p = 0.053]). Proportions of interventions with significant or very significant clinical impact were similar between the two groups but as fewer interventions were made centrally, a significant proportion of errors were probably not detected by the central validation.

On-ward pharmaceutical validation leads to a higher rate of prescribing error detection. Pharmaceutical interventions made by on-ward pharmacists are also better accepted and more relevant, going further than CDS-alerts.