Impact of Pharmacist Interventions in a Portuguese Hospital: A Study Using the CLEO Multidimensional Tool

(1) Background: Pharmacist interventions are key to optimizing medication therapy and improving patient outcomes. The CLEO multidimensional tool assesses the clinical, economic, and organizational impact of these interventions, though its use in Portuguese hospital settings is limited. This study explored the predicted impact of pharmacist interventions in the Oncology Department of a Portuguese hospital, using CLEO to quantify their potential contribution to patient care and healthcare system efficiency;(2) Methods: A retrospective observational study was conducted at the hospital's Oncology Outpatient Pharmacy between April and December 2024. Data from 144 pharmacist interventions were analyzed, focusing on drug-related problems, corrective actions, and CLEO scores. Descriptive statistics were used for data analysis; (3) Results: The most frequent drug-related problems were incorrect administration frequency (57.6%), drug interactions (22.2%), and incorrect dosing (10.4%). Nearly half of the interventions (47.2%) resulted in prescription corrections. CLEO analysis demonstrated a predicted positive clinical impact (80% of interventions scored 1C-3C), potential economic benefits (40.3% scored 1E), and organizational improvements (79.9% scored 1O), especially in lung, breast, and colorectal cancer treatments; (4) Conclusions: Pharmacist interventions were predicted to be associated with improvements in clinical, economic, and organizational outcomes in oncology care. These findings suggest that systematic documentation and evaluation of interventions using CLEO may enhance patient safety and healthcare efficiency, although further multicenter and prospective studies are needed to confirm these observations.