Emergency Department Database (EDD) Reporting

Publication MAterials

Massachusetts Acute Care Hospital Emergency Department Data (FFY 2016-2019) Report

(Published September 2021)

This report provides insight into emergency department visits in all acute care hospitals in Massachusetts over a four-year period, from FFY 2016 to FFY 2019 (October 1, 2015 to September 30, 2019). This report presents key measures of ED utilization overall and by hospital, patient, and visit characteristics and is also accompanied by a databook and technical appendix.

Under state law, CHIA maintains a database of stay-level encounters with acute care hospitals going back more than 20 years. Collectively known as Case Mix, the databases capture each inpatient admission, emergency department visit, and outpatient observation stay in all acute care hospitals in Massachusetts. Case Mix captures the medical reason for the visit, procedures and services provided, charges incurred, and duration of the visit, as well as patient demographics.

This is the first annual statewide report on ED utilization and part of a new reporting series providing analyses of patterns and trends of acute care hospital services from CHIA’s Case Mix database. In addition to this report, CHIA has published a parallel report on inpatient visits in Massachusetts in December 2020 and is currently developing a report on outpatient observation visits in the Commonwealth. In the future, CHIA will produce data updates on a regular basis for all three settings of care to provide timely access to key analyses from these data as they are submitted and processed by the agency.

For further information about the Massachusetts Acute Hospital Case Mix Database (Case Mix), including information about data governance, data submissions, data enhancements, and use cases, please see the Overview of the Massachusetts Acute Hospital Case Mix Database (December 2019).


Key Findings:    

  • In FFY 2019, there were over 3.1 million ED visits in the Commonwealth.

  • Medicaid was the most common expected payer type (31.8%); Medicaid and Medicare together were the expected primary payer type for a majority of ED visits (60.0%).

  • ED visits with behavioral health primary diagnoses were nearly twice as common among Medicaid patients as among Medicare and commercially insured patients (11.3%, 6.1%, 6.6% respectively).

  • Patients with a history of frequent ED use represented 1.2% of ED patients and accounted for 9.4% of all ED visits.

  • Over 32% of treat-and-release visits lasted more than four hours; this was twice as common among treat-and-release visits with a behavioral health primary diagnosis.