Site of Ambulance Origination and Billing for Out-of-Network Services.

Importance: The No Surprises Act implemented in 2022 aims to protect patients from surprise out-of-network (OON) bills, but it does not include ground ambulance services. Understanding ground ambulance OON and balance billing patterns from previous years could guide legislation aimed to protect patients following ground ambulance use.

Objective: To characterize OON billing from ground ambulance services by evaluating whether OON billing risk differs by the site of ambulance origination (home, hospital, nonhospital medical facility, or scene of incident).

Design, Setting, And Participants: Cross-sectional study of the Merative MarketScan dataset between January 1, 2015, and December 31, 2020, using claims-based data from employer-based private health insurance plans in the US. Participants included patients who utilized ground ambulances during the study period. Data were analyzed from June to December 2023.

Exposure: Medical encounter requiring ground ambulance transportation.

Main Outcomes And Measures: Ground ambulance OON billing prevalence was calcuated. Linear probability models adjusted for state-level mixed effects were fit to evaluate OON billing probability across ambulance origins. Secondary outcomes included the allowed payment, patient cost-sharing amounts, and potential balance bills for OON ambulances.

Results: Among 2 031 937 ground ambulance services (1 375 977 unique patients) meeting the inclusion and exclusion criteria, 1 072 791 (52.8%) rides transported men, and the mean (SD) patient age was 41 (18) years. Of all services, 1 113 676 (54.8%) were billed OON. OON billing probabilities for ambulances originating from home or scene were higher by 12.0 percentage points (PP) (95% CI, 11.8-12.2 PP; P < .001 for home; 95% CI, 11.7-12.2 PP; P < .001 for scene) vs those originating from hospitals. Mean (SD) total financial burden, including cost-sharing and potential balance bills per ambulance service, was $434.70 ($415.99) per service billed OON vs $132.21 ($244.92) per service billed in-network.

Conclusions And Relevance: In this cross-sectional study of over 2 million ground ambulance services, ambulances originating from home, the scene of an incident, and nonhospital medical facilities were more likely to result in OON bills. Legislation is needed to protect patients from surprise billing following use of ground ambulances, more than half of which resulted in OON billing. Future legislation should at minimum offer protections for these subsets of patients often calling for an ambulance in urgent or emergent situations.