Dual-comparator Taiwan cohort strengthens the evaluation case for emergency-department-initiated OPAT

A retrospective cohort study across two Taiwanese teaching hospitals (2017–2019) evaluated emergency-department-initiated outpatient parenteral antimicrobial therapy (OPAT) using coarsened exact matching, producing two separate comparator groups from 986 of 1,409 eligible patients: an inpatient-matched group to assess effectiveness, and an outpatient-matched group to assess safety. Against the inpatient comparator, OPAT saved a net 8.9 hospital-days per patient over 30 days and reduced costs by NT$34,367 per patient. Against the outpatient comparator, OPAT carried a transiently higher risk of return visits at day 7 (a 5-percentage-point absolute increase, p=0.008), without a corresponding increase in severe adverse events or 14-day readmissions, though it cost more than standard outpatient care.

Primary Study evidence of this kind is methodologically stronger than the single-comparator designs that dominate OPAT evaluation: matching against both an inpatient and an outpatient group separates the effectiveness question from the safety question rather than conflating them. No UK data appears in this study, so no claim about UK services follows from it directly — its value here is as a template for evaluation design: a service auditing its own emergency-department-initiated OPAT pathway has a working example of how to test both what is saved against admission and what is risked against standard outpatient care, in the same evaluation.