Outpatient Observation Database (OOD) Reporting

Publication MAterials

Outpatient Observation Database (OOD) Reporting

(Published January 2022)

This report provides insight into observation 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 observation department utilization overall and by hospital, patient demographic, 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 observation department 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 parallel reports on inpatient visits in Massachusetts in December 2020 and emergency department visits in September 2021. 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 Case Mix, including information about data governance, data submissions, data enhancements, and use cases, please see CHIA's Overview of the Massachusetts Acute Hospital Case Mix Database (December 2019).


Key Findings:    

  • In FFY 2019, there were 330,324 total observation visits among Massachusetts acute care hospitals: two-thirds of those observation visits (216,037) were observation only and one-third (114,287) resulted in an inpatient admission. 

  • Although the number of observation visits has remained relatively stable over the past four years, the proportion of visits associated with behavioral health increased by 20.2%.

  • Over half (51.2%) of all observation visits were among non-elderly adults (aged 18-64); elderly adults (65 and older) represented another 40.0% of visits, and children represented 8.8% of visits. 

  • The most common expected primary payer type for observation visits was Medicare (42.4%), followed by commercial insurance (27.6%) and Medicaid (22.7%).