The Utility of a Novel Definition of Healthcare Regions in the United States in the Era of COVID-19: A Validation of the Pittsburgh Atlas using Pneumonia Admissions

Abstract Objective The COVID-19 pandemic in the United States has underscored the need to understand healthcare in a regional context. However, there are multiple definitions of healthcare regions available for conducing geospatial analyses. In this study, we compare the novel Pittsburgh Atlas, which defined regions for emergency care, to existing definitions of regions, counties and the Dartmouth Atlas, with respect to non-emergent acute medical conditions by using pneumonia admissions. Methods We identified patients hospitalized with a primary diagnosis of pneumonia or a primary admitting diagnosis of sepsis with a secondary diagnosis of pneumonia in the Agency for Healthcare Research and Quality’s State Inpatient Databases. We calculated percentage of region concordant care the localization index and market share for three definitions of healthcare regions (the Pittsburgh Atlas, Dartmouth Atlas, and counties). We used logistic regression identified predictors of region concordant care. Results We identified 1,582,287 patients meeting inclusion criteria. We found that the Pittsburgh Atlas and Dartmouth Atlas definitions of regions performed similarly with respect to both localization index (92.0 [Interquartile range (IQR): 87.9-95.7] vs 90.3 [IQR: 81.4-94.5]) and market share (8.5 [IQR 5.1 – 13.6] vs 9.4 [6.7 – 14.1]). Both atlases outperformed the localization index (67.5 [IQR 49.9 – 83.9]) and market share (20.0% [IQR 11.4 – 31.4]) of counties. Within a given referral region, demographic factors including age, gender, race/ethnicity, insurance status, and level of acuity all affected concordance rates between residential and hospital regions. Conclusion Because the Pittsburgh Atlas also has the benefit of respecting state and county boundaries, use of this definition may have improved policy applicability without sacrificing accuracy in defining healthcare regions for acute medical conditions.