Background To demonstrate the added value that pharmacists bring, it is essential that all activities undertaken to improve therapy in the hospital are recorded and quantified.

Purpose To analyse the pharmaceutical interventions with potential to avoid adverse drug events (ADE) in hospitalised patients and to calculate the cost avoided with them.

Material and methods Retrospective study of pharmaceutical interventions carried out over 3 months, using the registration in the pharmacy software and its exportation to Excel, where variables were registered. Avoided cost was calculated from multiplying 1.7 days, which is the average stay increase due to an ADE according to the bibliography, cost of the stay and probability of ADE occurrence if it had not been intervened.

Results Over a period of 3 months, 10 pharmacists performed 1238 interventions, in 958 hospitalised patients in charge of 15 clinical departments: 18.7% of interventions were carried out in internal medicine, 16.2% in traumatology, 14.8% in general surgery, 10.9% in urology and8.4% in gynaecology-obstetrics. Reasons for intervention were: treatment reconciliation (41.4%), therapeutic exchange (16.5%), narrow therapeutic window/high-risk drug (9.6%), moderate adverse reaction (6.9%), renal impairment adjustment (4%), relevant interaction (3.5%), 2 to 4 times upper/lower dosage (2.7%), other dosage adjustments (2.7%), therapeutic doubling (2.2%), other optimisations (1.5%), severe adverse reaction (1.5%), clarification/completing medical order (1.3%), adequacy of antibiotic treatment (1.3%), providing relevant information (1.2%), low-risk drug lacking/remaining (1.1%), pharmaceutical form/administration route with toxicity risk or therapeutic failure (0.8%), allergy (0.6%), sequential therapy (0.6%), four to 10 times upper/lower dose (0.2%), mild adverse reaction (0.2%) and asking for blood test (0.2%). Acceptance of interventions was 84.7%, with 7.2% interventions being non-valued. Accepted pharmaceutical interventions were estimated to have avoided a cost of €169,816, by preventing prolongation of the hospital stay due to ADE.

Conclusion Registration of pharmaceutical interventions is essential for analysing and quantifying the role of the pharmacist as part of the care team. This study allows us to conclude that the pharmacist is involved in optimising the pharmacotherapy of hospitalised patients in all clinical departments, contributing to the prevention of ADE, which means an increase in patient safety, as well as cost savings for the sanitary system.

No conflict of interest