PURPOSE: The evidence guiding the decision to provide injectable anticoagulant bridging therapy during periods of subtherapeutic warfarin anticoagulation is sparse. This study aims to identify the types of patients currently bridged within an academic medical center's Thrombosis Service, to highlight patient populations for future study of bridging outcomes. METHODS: This descriptive cohort study included patients taking warfarin managed by University of Utah Health Thrombosis Service who received outpatient enoxaparin bridging between January 1 and December 31, 2022. Anticoagulation indication, reason for bridging, and type of procedure were validated via manual chart review. RESULTS: During the one-year study period, 181 unique patients (9.4 % of the service's total warfarin population) experienced 244 bridging episodes, mostlyin the periprocedural setting (67.6 %) for gastrointestinal-type procedures (39.4 %). The most common anticoagulation indications in all bridged patients were antiphospholipid syndrome (APS) (23.2 %), venous thromboembolism (VTE) (21.5 %), or a mechanical mitral valve plus another indication (13.3 %). Most bridging episodes for VTE occurred >
3 months from the acute event, with the rationale for bridging including breakthrough VTE (31 %) or APS (23 %). Just over one-half of bridged patients fit the guideline-recommended criteria for high thrombotic risk, and just over one-third were low-moderate thrombotic risk. CONCLUSIONS: In this one-year outpatient study, warfarin patients received enoxaparin bridging most commonly due to a gastrointestinal procedural interruption in the setting of APS, VTE with a prior breakthrough thrombotic event, or mechanical mitral valve. Just over one-third of bridged patients were guideline-classified as low-moderate thrombotic risk, indicating these populations may warrant further investigation or bridging de-escalation.