Assessment of Out-of-Network Billing for Privately Insured Patients Receiving Care in In-Network Hospitals.

IMPORTANCE Although surprise medical bills are receiving considerable attention from lawmakers and the news media, to date there has been little systematic study of the incidence and financial consequences of out-of-network billing. OBJECTIVE To examine out-of-network billing among privately insured patients with an inpatient admission or emergency department (ED) visit at in-network hospitals. DESIGN, SETTING, AND PARTICIPANTS A retrospective analysis using data from the Clinformatics Data Mart database (Optum), which includes health insurance claims for individuals from all 50 US states receiving private health insurance from a large commercial insurer was conducted of all inpatient admissions (n = 5457981) and ED visits (n = 13579006) at in-network hospitals between January 1, 2010, and December 31, 2016. Data were collected and analyzed in March 2019. EXPOSURES Receipt of a bill for care from at least 1 out-of-network physician or medical transport service associated with patient admission or ED visit. MAIN OUTCOMES AND MEASURES The incidence of out-of-network billing and the potential amount of patients' financial liability associated with out-of-network bills from the admission or visit. RESULTS Of 5457981 inpatient admissions and 13579006 ED admissions between 2010 and 2016, the percentage of ED visits with an out-of-network bill increased from 32.3% to 42.8% (P < .001) during the study period, and the mean (SD) potential financial responsibility for these bills increased from $220 ($420) to $628 ($865) (P < .001; all dollar values in 2018 US$). Similarly, the percentage of inpatient admissions with an out-of-network bill increased from 26.3% to 42.0% (P < .001), and the mean (SD) potential financial responsibility increased from $804 ($2456) to $2040 ($4967) (P < .001). CONCLUSIONS AND RELEVANCE Out-of-network billing appears to have become common for privately insured patients even when they seek treatment at in-network hospitals. The mean amounts billed appear to be sufficiently large that they may create financial strain for a substantial proportion of patients.