Variation, Overlap, and Stability in Defining Safety Net Hospitals.

Area of Science:

• Health Services Research
• Health Policy Analysis
• Hospital Management

Background:

• The lack of standardized definitions for safety net hospitals (SNHs) hinders effective policy development and support for the populations they serve.
• Accurate identification of SNHs is critical for resource allocation and understanding healthcare access for vulnerable populations.

Purpose of the Study:

• To evaluate the overlap, variation, and consistency among different definitions of safety net hospital (SNH) status.
• To compare hospital characteristics and sample stability across various SNH definitions over time.

Main Methods:

• A retrospective cohort study analyzed US short-term acute care hospital data from 2014 to 2022.
• Nine hospital-level and four area-level measures were used to define SNHs, including Medicare Disproportionate Share (DSH) index, patient demographics, and socioeconomic factors.
• Analyses described hospital characteristics, definition overlap, and the temporal stability of SNH samples.

Main Results:

• Between 21.9% and 29.3% of hospitals qualified as SNHs in 2022, varying significantly by definition.
• Definitions based on absolute patient numbers identified larger, non-rural hospitals, while relative measures identified smaller, rural hospitals.
• The Medicare DSH index and Medicaid inpatient day share showed the highest overlap (55%), while public ownership and teaching status demonstrated the most temporal stability for SNH definitions.

Conclusions:

• Existing definitions of safety net hospitals (SNHs) produce substantially different hospital samples with variable overlap and stability.
• The choice of definition impacts the characteristics of identified SNHs, highlighting trade-offs in policy design.
• Further research is needed to establish consistent and reliable methods for defining SNHs to better support targeted healthcare initiatives.