Do Avoidable Hospitalization Rates among Older Adults Differ by Geographic Access to Primary Care Physicians?

Abstract

Objective: To investigate the association between older adults' potentially avoidable hospitalization rates and both a geographic measure of primary care physician (PCP) access and a standard bounded-area measure of PCP access.

Data sources: State physician licensure data from the Virginia Board of Medicine. Patient-level hospital discharge data from Virginia Health Information. Area-level data from the American Community Survey and the Area Health Resources Files. Virginia Information Technologies Agency road network data. US Census Bureau TIGER/Line boundary files.

Study design: We use enhanced two-step floating catchment area methods to calculate geographic PCP accessibility for each ZIP Code Tabulation Area in Virginia. We use spatial regression techniques to model potentially avoidable hospitalization rates.

Data collection/extraction: Geographic accessibility was calculated using ArcGIS. Physician locations were geocoded using TAMU GeoServices and ArcGIS.

Principal findings: Increased geographic access to PCPs is associated with lower rates of potentially avoidable hospitalization among older adults. This association is robust, allowing for spatial spillovers in spatial lag models.

Conclusions: Compared to bounded-area density measures, unbounded geographic accessibility measures provide more robust evidence that avoidable hospitalization rates are lower in areas with more PCPs per person. Results from our spatial lag models reveal the presence of positive spatial spillovers.

Keywords: Geographic accessibility; potentially avoidable hospitalization; primary care provider; spatial analysis.

Figure 1

Potentially Avoidable Hospitalization Rates by Quintile

1. Notes. This map displays the distribution of the 2‐year avoidable hospitalization rate per 1,000 persons age 65 years and older across Virginia ZCTAs. The quintile ranges are as follows: quintile 1, less than 59.3; quintile 2, greater than or equal to 59.3 and less than 81.0; quintile 3, greater than or equal to 81.0 and less than 102.9; quintile 4, greater than or equal to 102.9 and less than 139.1; and quintile 5, greater than or equal to 139.1.

Figure 2

Measure of Geographic Accessibility to Primary Care Physicians by Quintile

1. Notes. This map displays the distribution of the E2SFCA‐based measure of the primary care physician to population ratio across Virginia ZCTAs. The quintile ranges are as follows: quintile 1, less than 0.282; quintile 2, greater than or equal to 0.282 and less than 0.441; quintile 3, greater than or equal to 0.441 and less than 0.641; quintile 4, greater than or equal to 0.641 and less than 0.941; and quintile 5, greater than or equal to 0.941.