- This study sought to quantify the association between event notifications and subsequent query-based health information exchange (HIE) use among end users of three different community health information organizations.Using system-log data merged with user characteristics, regression-adjusted estimates were used to describe the association between event notifications and subsequent query-based HIE usage.Approximately 5% of event notifications were associated with query-based HIE usage within 30 days. In adjusted models, odds of query-based HIE usage following an event notification were higher for older patients and for alerts triggered by a discharge event. Query-based HIE usage was more common among specialty clinics and Federally Qualified Health Centers than primary care organizations.In this novel combination of data, 1 in 20 event notifications resulted in subsequent query-based HIE usage. Results from this study suggest that event notifications and query-based HIE can be applied together to address clinical and population health use cases.© The Author(s) 2019. Published by Oxford University Press on behalf of the American Medical Informatics Association.