Patients referred to but not taken on to an outpatient parenteral antimicrobial therapy (OPAT) service: the impact of infection specialist advice on the assessment and clinical outcomes.

Objectives: This study explored antimicrobial stewardship opportunities, clinical impact and patient outcomes in those referred to an outpatient parenteral antimicrobial therapy (OPAT) service, screened by an infection specialist but not taken on in a large tertiary centre. Methods: All OPAT referrals that were screened but not taken on by the NHS Greater Glasgow and Clyde OPAT service over a 3 year period (2022-2024) were reviewed. Those that were advised an oral antibiotic option that did not require close monitoring and did not require specialist OPAT follow-up were analysed for reason for referral, duration of antibiotic prescribed and patient outcome (readmission and mortality) at 30 days. Results: During the study period 5024 patients were referred to OPAT and 1467 (29.2%) were not taken onto the service. Of these 517 (35%) were given advice to switch to an oral antibiotic option that did not require specific OPAT monitoring. These included referrals for bone and joint, complex intra-abdominal and Conclusions: These data highlight the central role of antimicrobial stewardship in OPAT gate keeping and the importance of measuring the unseen and wider healthcare service impact of OPAT. Assuming those referred had remained on IV therapy then the equivalent of 13 909 days of inpatient or OPAT IV days was avoided.