{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,11]],"date-time":"2026-05-11T11:07:46Z","timestamp":1778497666750,"version":"3.51.4"},"reference-count":24,"publisher":"Wiley","issue":"4","license":[{"start":{"date-parts":[[2024,4,30]],"date-time":"2024-04-30T00:00:00Z","timestamp":1714435200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"funder":[{"DOI":"10.13039\/100000050","name":"National Heart, Lung, and Blood Institute","doi-asserted-by":"publisher","award":["5 R01 HL113550"],"award-info":[{"award-number":["5 R01 HL113550"]}],"id":[{"id":"10.13039\/100000050","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Health Services Research"],"published-print":{"date-parts":[[2024,8]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Objective<\/jats:title><jats:p>To develop an accurate and reproducible measure of vertical integration between physicians and hospitals (defined as hospital or health system employment of physicians), which can be used to assess the impact of integration on healthcare quality and spending.<\/jats:p><\/jats:sec><jats:sec><jats:title>Data Sources and Study Setting<\/jats:title><jats:p>We use multiple data sources including from the Internal Revenue Service, the Centers for Medicare and Medicaid Services, and others to determine the Tax Identification Numbers (TINs) that hospitals and physicians use to bill Medicare for services, and link physician billing TINs to hospital\u2010related TINs.<\/jats:p><\/jats:sec><jats:sec><jats:title>Study Design<\/jats:title><jats:p>We developed a new measure of vertical integration, based on the TINs that hospitals and physicians use to bill Medicare, using a broad set of sources for hospital\u2010related TINs. We considered physicians as hospital\u2010employed if they bill Medicare primarily or exclusively using hospital\u2010related TINs. We assessed integration status for all physicians who billed Medicare from 1999 to 2019. We compared this measure with others used in the existing literature. We conducted a simulation study which highlights the importance of accurately identifying integrated physicians when study the effects of integration.<\/jats:p><\/jats:sec><jats:sec><jats:title>Data Collection\/Extraction Methods<\/jats:title><jats:p>We extracted physician and hospital\u2010related TINs from multiple sources, emphasizing specificity (a small proportion of nonintegrated physicians identified as integrated).<\/jats:p><\/jats:sec><jats:sec><jats:title>Principal Findings<\/jats:title><jats:p>We identified 12,269 hospital\u2010related TINs, used for billing by 546,775 physicians. We estimate that the percentage of integrated physicians rose from 19% in 1999 to 43% in 2019. Our approach identifies many additional physician practices as integrated; a simpler TIN measure, comparable with prior work, identifies only 30% (3877) of the TINs we identify. A service location measure, used in prior work, has both many false positives and false negatives.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>We developed a new measure of hospital\u2010physician integration. This measure is reproducible and identifies many additional physician practices as integrated.<\/jats:p><\/jats:sec>","DOI":"10.1111\/1475-6773.14314","type":"journal-article","created":{"date-parts":[[2024,5,1]],"date-time":"2024-05-01T06:23:41Z","timestamp":1714544621000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["A more complete measure of vertical integration between physicians and hospitals"],"prefix":"10.1111","volume":"59","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3413-9727","authenticated-orcid":false,"given":"Qian (Eric)","family":"Luo","sequence":"first","affiliation":[{"name":"Milken Institute School of Public Health George Washington University  Washington DC USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bernard","family":"Black","sequence":"additional","affiliation":[{"name":"Pritzker School of Law, Institute for Policy Research, and Kellogg School of Management Northwestern University  Chicago Illinois USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"David J.","family":"Magid","sequence":"additional","affiliation":[{"name":"University of Colorado, Anschutz Medical Campus  Aurora Colorado USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Frederick A.","family":"Masoudi","sequence":"additional","affiliation":[{"name":"Ascension Health  Saint Louis Missouri USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7531-7331","authenticated-orcid":false,"given":"Vinay","family":"Kini","sequence":"additional","affiliation":[{"name":"Division of Cardiology Weill Cornell Medical College  New York New York USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1728-6434","authenticated-orcid":false,"given":"Ali","family":"Moghtaderi","sequence":"additional","affiliation":[{"name":"Milken Institute School of Public Health George Washington University  Washington DC USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2024,4,30]]},"reference":[{"issue":"3","key":"e_1_2_9_2_1","first-page":"172","article-title":"Trends in hospital\u2010ownership of physician practices and the effect on processes to improve quality","volume":"22","author":"Bishop TF","year":"2016","journal-title":"Am J Manag Care"},{"key":"e_1_2_9_3_1","doi-asserted-by":"publisher","DOI":"10.1377\/hlthaff.2017.0054"},{"key":"e_1_2_9_4_1","doi-asserted-by":"publisher","DOI":"10.1377\/hlthaff.2017.1520"},{"key":"e_1_2_9_5_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1475\u20106773.2004.00227.x"},{"key":"e_1_2_9_6_1","doi-asserted-by":"publisher","DOI":"10.1186\/1472\u20106963\u201011\u201036"},{"key":"e_1_2_9_7_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.jhealeco.2016.08.006"},{"key":"e_1_2_9_8_1","doi-asserted-by":"crossref","unstructured":"EncinosaW DorA NguyenP.Does physician\u2010hospital vertical integration signal care\u2010coordination? 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