Growth in health information exchange with ACO market penetration

First, to assess whether hospitals expand the network breadth of their health information exchange (HIE) partners after joining an accountable care organization (ACO). Second, to analyze whether this HIE network expansion effect varies across markets with differing levels of ACO penetration.

Difference-in-differences analyses of US nonfederal acute care hospitals, 2014-2017.

We used data from the American Hospital Association Annual Survey and Information Technology Supplement to measure hospital ACO participation, HIE network breadth (defined as number of different partner types), and ACO market penetration at the hospital referral region level. We implemented a difference-in-differences model to estimate changes in hospitals' HIE network breadth with ACO participation in different years. We estimate these effects combined across all markets and stratified by markets with high and low ACO market penetration.

In combined analyses, HIE breadth increased by 0.35 partner types with ACO participation, a 30.7% increase (P < .001). In stratified analyses, this effect was larger for hospitals in high-ACO penetration markets (0.41 partner types, a 32.0% increase; P < .001) and smaller for hospitals in low-ACO penetration markets (0.25 partner types, a 24.8% increase; P < .05). We found dynamic effects of ACO adoption illustrating an immediate effect in high-ACO penetration markets and a 2-year delayed effect in low-ACO penetration markets.

Hospitals that joined ACOs increased their HIE breadth, but this effect was heterogenous across markets and across time. Our findings illustrate a "network effect," with large, immediate effects in HIE breadth following ACO participation in high-ACO penetration markets and smaller, delayed effects in low-ACO penetration markets.