When Ambulances Wait at the Emergency Department: Hospital Factors and Offload Times in California

Abstract Introduction Ambulance patient offload time (APOT), the interval between ambulance arrival at the emergency department (ED) and transfer of care, is an understudied measure of emergency care delivery. We examined associations between hospital characteristics and APOTs across 310 California EDs before Assembly Bill (AB) 40 established statewide APOT reduction requirements. Methods We conducted a retrospective cross-sectional study using data from the California Emergency Medical Services (EMS) Authority, 34 local EMS agencies, and the California Department of Health Care Access and Information. The primary outcome was APOT-1, the time within which 90% of EMS-ED transfers are completed. We used LASSO for predictor selection and fitted three nested negative binominal regression models. Results Among 310 EDs, 77.7% were urban, 62.9% were nonprofit, and 89.0% were non-teaching. Urban location and more ED treatment stations were associated with longer APOT-1. Predicted APOT-1 ranged from 9.7 to 19.3 minutes in rural EDs and 19.4 to 38.7 minutes in urban EDs. Policy Implications This study provides baseline data on patient handoff between EMS crews and ED staff prior to the implementation of AB 40. Addressing APOT delays requires coordinated strategies beyond individual EDs or EMS agencies.