Implementation and Clinical Impact of a Structured Clinical Pharmacy Service for Hospitalized Ileostomy Patients: A Retrospective Observational Study Using the RE-AIM Framework

Patients with ileostomy face unique pharmacotherapeutic challenges, including altered drug absorption, yet structured pharmaceutical care for this population is rarely integrated into routine clinical practice. This retrospective monocentric cohort study evaluated the reach, effectiveness, adoption, implementation, and maintenance of a structured ileostomy-specific clinical pharmacy service using the implementation science-based RE-AIM framework at a 1245-bed teaching hospital in Vienna, Austria. Sixty-two patients (54.8% male; median age of 65.5 years) were included, receiving a median of 11 medications. A total of 324 drug-related problems (DRPs) were identified, of which 202 (62.3%) were classified as stoma-specific drug-related problems (SDRPs), representing a predefined subgroup of DRPs associated with ileostomy-related pharmacotherapy challenges. This distinction enabled separate evaluation of the clinical relevance of stoma-specific pharmaceutical interventions. The implementation rate was significantly higher for SDRP-related interventions than for general DRP recommendations (92.0% vs. 63.9%; p < 0.001), with no significant interdepartmental differences observed in either DRPs (p = 0.137) or SDRPs (p = 0.071). Patients with high-output stoma (HOS) had significantly more SDRPs than those without (p < 0.001), while no differences were observed in general DRPs. The service demonstrated wide adoption, high interprofessional acceptance, full protocol fidelity, and continuous implementation over 30 months. The findings provide implementation evidence that may support healthcare decision-makers, hospital administrators, and policy stakeholders in establishing and sustaining structured clinical pharmacy services for ileostomy patients in Austria and similar healthcare settings.