Background and importance 4.7% of Spanish hospital patients suffer a preventable adverse event (AE) due to medication errors. In surgical specialties, errors may result in important negative consequences, so hospital pharmacists have implemented new programmes to prevent them.

We created a Presurgical Pharmaceutical Care Consultation in 2016 to avoid errors prior to surgery with managing a patient’s chronic medication.

Aim and objectives The aim was to analyse the economic impact of implementing this consultation based on the presurgical medication errors avoided with pharmaceutical interventions.

Material and methods We analysed all the interventions performed by pharmacists in the Presurgical Pharmaceutical Care Consultation between 2016 and 2020 in Traumatology, General, Cardiac and Thoracic Surgery Services of a third-level hospital.

Two clinical pharmacists and two anaesthesiologists composed a multidisciplinary team for intervention analysis and classification. Each prevented error was classified according to its probability of causing an AE, based on literature and clinical judgement. Assigned probability could be 0, 0.01, 0.1, 0.4 or 0.6 (1 was not considered due to a conservative approach).We calculated the cost of each prevented error as: ‘AE probability * €6924’, €6924 being the cost of an AE according to the Spanish literature, adjusted by the 2020 Consumer Price Index. A sensitivity analysis was performed using an AE cost 20 % higher or lower. The total cost of hiring pharmacists (one full-time pharmacist in the consultation during 5 years ) was €227 470 (€45 494 per year).

Results Between 2016 and 2020, 3101 patients were assisted in our Consultation (51.30% male, mean age 66.4 years), on whom 1179 interventions were performed to prevent medication errors. Classification according to probability of causing an AE was as follows: 0: 6 (0.5%), 0.01: 224 (19.0%), 0.1: 346 (29.3%), 0.4: 497 (42.2%) and 0.6: 106 (9.0%), meaning that 299 AE could be avoided in total. Cost avoidance was estimated at €2 076 785 (sensitivity analysis €1 657 490–€2 486 385). Cost–benefit ratio of the Presurgical Pharmacist Consultation was €9.1 in savings for each invested euro (sensitivity analysis €5.4–€10.9).

Conclusion and relevance The implementation of our Presurgical Pharmaceutical Care Consultation was cost-effective, preventing more than 200 medication errors per year. It could be extrapolated to other hospitals in order to improve surgical patient safety in a cost-effective way.

Conflict of interest No conflict of interest