Abstract
OBJECTIVES: This study aimed to develop a measure of health information exchange (HIE) for characterizing the density of inter-hospital HIE connections and identify regional characteristics associated with HIE network density. METHODS: HIE network density was measured as the proportion of hospital pairs within a region that are connected through HIE. The 2022 American Hospital Association's Information Technology Supplement survey was used to calculate HIE network density for US hospital referral regions (HRRs). Bivariate tests and multivariable regression were used to characterize hospital, electronic health record (EHR) vendor, and resident characteristics associated with HIE network density. RESULTS: Data on 2,509 hospitals across 274 HRRs were included in the study, with 92% of hospitals participating in at least one HIE. On average, hospitals participated in two HIEs and there were seven HIEs present in each region. HIE network density ranged from 0.0 to 1.0, with a median of 0.78 and an interquartile range (IQR) of 0.51-1.00. Hospital and vendor characteristics associated with greater HIE network density include: more HIEs per hospital, a higher proportion of non-profit hospitals, greater Epic market share, and more concentrated hospital and EHR vendor markets. Resident characteristics associated with greater HIE network density include: higher home values, more educated residents, and higher median household incomes. CONCLUSION: We found that, on average, 7 out of 10 hospital pairs within a given HRR are connected via at least one HIE, with lower HIE network density in regions with lower socioeconomic status. This measure can be used to track the impact of the Trusted Exchange Framework and Common Agreement on area-level interoperability.