LAUSR

Importance Health insurers alter the size of their networks, offering lower premiums in exchange for a more limited set of care choices. However, little is known about the association of network size with health care utilization and outcomes, particularly outside of the context of private insurance plans. Objective To evaluate changes in health care utilization after an expansion in the Veterans Affairs Health Care System (VA) health care network. Design, Setting, and Participants This cross-sectional study included individuals enrolled in the VA from 2015 to 2018. Considering that the health care network expansion only affected a portion of enrollees, only those who lived between 20 and 60 miles from a VA facility were included. Data analysis was conducted from September 2020 to February 2021. Exposures Individuals who lived 40 or more miles away from a VA facility were automatically eligible for an expanded health care network through non-VA practitioners (VA community care); those living less than 40 miles away from a VA facility were not automatically eligible. Main Outcomes and Measures A regression discontinuity analysis of individuals who became eligible for an expanded network based on geographic residence was performed. Inpatient and outpatient utilization rates per VA enrollee during the study period, with utilization differentiated by whether services were provided by a VA or non-VA practitioner, were calculated. Results The study included more than 2.7 million unique individuals whose characteristics largely reflected the demographic characteristics of the VA system (mean [SD] age, 62 [17] years; 2 589 252 [90%] men; 282 168 [10%] Black; 2 203 352 [77%] White). Patient characteristics (age, race, and comorbidities) did not vary significantly by eligibility status. Outpatient utilization was 3.2% higher (95% CI, 1.0% to 5.3%) among those with access to an expanded network. Increased utilization was most pronounced among those with a higher VA disability rating (3.1%; 95% CI, 0.5% to 5.7%) and among younger individuals without service-connected disabilities (7.0%, 95% CI, 1.7% to 12.3%). There was no evidence of changes to inpatient utilization (1.2%; 95% CI. -2.5% to 4.9%; P = .37) for those with access to the expanded network. Conclusions and Relevance In this study, expanded network access was associated with increased total health care utilization among affected enrollees in the VA. Understanding how network size affects utilization is immediately informative for the VA, but it can also help to guide policies for insurance markets.