Pharmacists in OPAT: a systematic review and meta-analysis

Background and objectives: Outpatient parenteral antimicrobial therapy (OPAT) is defined as the administration of at least two doses of parenteral antimicrobials in an outpatient setting without an overnight hospital admission. OPAT has demonstrated positive patient outcomes whilst reducing bed pressures in hospital and exposure to healthcare-associated infections. International infection societies stress the importance of a core multi-disciplinary team to manage OPAT services. However, many services do not have a pharmacist as part of this core group, with few studies evaluating their effectiveness. To evaluate current evidence for the impact of pharmacists working in OPAT settings on patient safety and outcomes. Methods: A PRISMA protocol was developed and published (PROSPERO CRD42023452470). Database literature search completed from conception to April 2025. Studies were required to have a pharmacist as part of the multi-disciplinary team alongside a comparator cohort. Results: We identified 918 studies, with ten meeting the eligibility criteria and all demonstrating a high risk of bias. Pharmacist intervention was found to increase adherence to therapeutic drug monitoring and antibiotic dose adjustment by 40–64% and reduce antimicrobial prescribing errors by 17%–22%. Complications, including re-admissions; emergency department (ED) visits and unfavourable outcomes, had less consistent results across studies. Conclusion: The findings of this systematic review and meta-analysis indicate that the involvement of pharmacists was associated with improvements in process outcomes such as adherence to drug monitoring protocols, but associations with health outcomes were less consistent. Further studies with robust protocols are required.