Development and Evaluation of Rehabilitation Service Areas for the United States

Abstract

Background: Geographic areas have been developed for many healthcare sectors including acute and primary care. These areas aid in understanding health care supply, use, and outcomes. However, little attention has been given to developing similar geographic tools for understanding rehabilitation in post-acute care. The purpose of this study was to develop and characterize post-acute care Rehabilitation Service Areas (RSAs) in the United States (US) that reflect rehabilitation use by Medicare beneficiaries.

Methods: A patient origin study was conducted to cluster beneficiary ZIP (Zone Improvement Plan) code tabulation areas (ZCTAs) with providers who service those areas using Ward's clustering method. We used US national Medicare claims data for 2013 to 2015 for beneficiaries discharged from an acute care hospital to an inpatient rehabilitation facility (IRF), skilled nursing facility (SNF), long-term care hospital (LTCH), or home health agency (HHA). Medicare is a US health insurance program primarily for older adults. The study population included patient records across all diagnostic groups. We used IRF, SNF, LTCH and HHA services to create the RSAs. We used 2013 and 2014 data (n = 2,730,366) to develop the RSAs and 2015 data (n = 1,118,936) to evaluate stability. We described the RSAs by provider type availability, population, and traveling patterns among beneficiaries.

Results: The method resulted in 1,711 discrete RSAs. 38.7% of these RSAs had IRFs, 16.1% had LTCHs, and 99.7% had SNFs. The number of RSAs varied across states; some had fewer than 10 while others had greater than 70. Overall, 21.9% of beneficiaries traveled from the RSA where they resided to another RSA for care.

Conclusions: Rehabilitation Service Areas are a new tool for the measurement and understanding of post-acute care utilization, resources, quality, and outcomes. These areas provide policy makers, researchers, and administrators with small-area boundaries to assess access, supply, demand, and understanding of financing to improve practice and policy for post-acute care in the US.

Keywords: Geographic variation; Medicare; Post-acute care; Small-area variation; Ward’s clustering method.

Fig. 1

Flowchart of the study methods for creating Rehabilitation Service Areas including steps of Ward’s clustering method. “States” refers to US states, CA California, FL Florida, MT Montana, ND North Dakota, NY New York, TX Texas, ZCTA ZIP [Zone Improvement Plan] Code Tabulation Area, PAC Post-acute care, RSA Rehabilitation Service Area, CMS Centers for Medicare and Medicaid Services

Fig. 2

Maps describing an example of disjoint area resolution, southern New Hampshire, US, Three Versions (V1, V2,V3). Dark red indicates ZCTAs that were not included in initial clustering due to a low number of records. Gray represents areas that are not ZCTAs (e.g., lakes mountains, etc.). All other colors are used to differentiate boundaries. Version 1 (V1): Clusters 22 (upper middle) and 23 (middle left) have formed disjoints and there are unused ZCTAs. Version 2 (V2): Unused ZCTAs were added to nearby clusters, but disjoint issues with clusters 22 and 23 remain. Version 3 (V3): Disjoint resolution; cluster 22 was resolved by splitting a ZCTA off of cluster 23 to bridge the two disjoint pieces; cluster 23 was resolved by splitting the two pieces into new clusters 61 and 62, and a ZCTA from cluster 18 was used to bridge the gap between the two pieces of cluster 61

Fig. 3

Map of Rehabilitation Service Areas for the entire United States. Gray represents areas that are not ZCTAs (e.g., lakes mountains, etc.). All other colors are used to differentiate boundaries