Comparing Self-Administered Outpatient Parenteral Antimicrobial Therapy (S-OPAT) with Alternative Delivery Models: Risk Factors for Treatment Failure and Complications in a UK Cohort

Self-administered outpatient parenteral antimicrobial therapy (S-OPAT) is an increasingly recognised antimicrobial delivery model, yet comparative evidence on its safety and effectiveness remains limited. We compared clinical outcomes across OPAT delivery models and examined predictors of adverse outcomes in S-OPAT. Adult OPAT episodes at a large UK teaching hospital (January 2023–January 2026) were categorised as S-OPAT, healthcare professional home-administered (H-OPAT), or clinic-based (C-OPAT). Primary outcomes were treatment failure, complications, and 30-day unplanned hospitalisation. Outcome risks were compared using robust multivariable Poisson regression with generalised estimating equations and Bonferroni correction. Among 1064 OPAT episodes, 286 (26.9%) were S-OPAT, and cure/clinical improvement occurred in 912/1064 (85.7%). Treatment failure occurred in 26/286 (9.1%) S-OPAT episodes, with no significantly higher risk than H-OPAT (adjusted relative risk [aRR], 0.72; 98.3% CI, 0.43–1.19) or C-OPAT (aRR, 0.94; CI 0.48–1.84). Rates of unplanned hospitalisation and OPAT-related complications were broadly comparable, except potentially vascular access-related events. Within S-OPAT, older age, higher comorbidity burden, diabetes, peripheral vascular disease, and central venous access were associated with treatment failure. Overall, these findings suggest that S-OPAT can be delivered safely and effectively to appropriately selected patients, while enhanced monitoring may be warranted for older individuals and those with greater comorbidity burden or central venous access devices.