{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T04:57:16Z","timestamp":1790830636199,"version":"4.1.0"},"reference-count":48,"publisher":"Wiley","license":[{"start":{"date-parts":[[2026,9,30]],"date-time":"2026-09-30T00:00:00Z","timestamp":1790726400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"},{"start":{"date-parts":[[2026,9,30]],"date-time":"2026-09-30T00:00:00Z","timestamp":1790726400000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Health Economics"],"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>Healthcare decision\u2010making often requires selecting among multiple treatment options under budget constraints, particularly when one option is more effective but also more costly. Cost\u2010effectiveness analysis (CEA) provides a framework for evaluating whether the health benefits of a treatment justify its additional costs. A key component of a CEA is the estimation of treatment effects on both health outcomes and costs, which becomes challenging when using observational data, due to potential confounding. While advanced causal inference methods exist for use in such circumstances, their adoption in CEAs remains limited, with many studies relying on overly simplistic methods such as linear regression or propensity score matching. In this paper, we address this gap by introducing cost\u2010effectiveness researchers to modern nonparametric regression models, with a particular focus on Bayesian Additive Regression Trees (BART). We provide guidance on how to implement BART in CEAs, including code examples, and discuss its advantages in producing more robust and credible estimates from observational data.<\/jats:p>","DOI":"10.1002\/hec.70153","type":"journal-article","created":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T04:23:25Z","timestamp":1790828605000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Nonparametric Regression for Cost\u2010Effectiveness Analyses With Observational Data\u2014A Tutorial"],"prefix":"10.1002","author":[{"ORCID":"https:\/\/orcid.org\/0009-0005-4964-5525","authenticated-orcid":false,"given":"Jonas","family":"Esser","sequence":"first","affiliation":[{"name":"Faculty of Science, Health Economics and Health Technology Assessment Vrije Universiteit Amsterdam  Amsterdam the Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7056-386X","authenticated-orcid":false,"given":"Mateus","family":"Maia","sequence":"additional","affiliation":[{"name":"School of Mathematics and Statistics University of Glasgow  Glasgow UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Judith E.","family":"Bosmans","sequence":"additional","affiliation":[{"name":"Faculty of Science, Health Economics and Health Technology Assessment Vrije Universiteit Amsterdam  Amsterdam the Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1606-8742","authenticated-orcid":false,"given":"Johanna Maria","family":"van Dongen","sequence":"additional","affiliation":[{"name":"Faculty of Science, Health Economics and Health Technology Assessment Vrije Universiteit Amsterdam  Amsterdam the Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,9,30]]},"reference":[{"key":"e_1_2_15_2_1","doi-asserted-by":"publisher","DOI":"10.1353\/obs.2025.a956837"},{"key":"e_1_2_15_3_1","doi-asserted-by":"publisher","DOI":"10.1146\/annurev\u2010statistics\u2010031017\u2010100404"},{"key":"e_1_2_15_4_1","doi-asserted-by":"publisher","DOI":"10.1093\/biomet\/87.2.329"},{"key":"e_1_2_15_5_1","doi-asserted-by":"publisher","DOI":"10.1007\/s40273\u2010023\u201001301\u20107"},{"key":"e_1_2_15_6_1","doi-asserted-by":"publisher","DOI":"10.1002\/hec.4263"},{"key":"e_1_2_15_7_1","doi-asserted-by":"publisher","DOI":"10.1002\/hec.941"},{"key":"e_1_2_15_8_1","doi-asserted-by":"publisher","DOI":"10.1111\/rssa.12824"},{"key":"e_1_2_15_9_1","doi-asserted-by":"publisher","DOI":"10.1111\/ectj.12097"},{"key":"e_1_2_15_10_1","doi-asserted-by":"publisher","DOI":"10.1214\/09\u2010aoas285"},{"key":"e_1_2_15_11_1","doi-asserted-by":"publisher","DOI":"10.3109\/02770903.2014.999283"},{"key":"e_1_2_15_12_1","doi-asserted-by":"publisher","DOI":"10.1214\/18\u2010sts667"},{"key":"e_1_2_15_13_1","volume-title":"Methods for the Economic Evaluation of Health Care Programmes","author":"Drummond M. 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