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Compared with non-POSA, POSA patients had lower AHI (24.1 vs. 44.4 events\/h,\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.001), lower BMI (29.2 vs. 31.4\u00a0kg\/m\u00b2,\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.001), and were slightly younger. No sex differences were observed for POSA, although e-POSA was more frequent in women (\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.001). After adjustment for AHI, POSA remained characterized by shorter sleep and REM latency, longer total sleep time, higher sleep efficiency, greater proportion of N3, improved oxygenation (higher mean SpO\u2082 and lower T90), and lower arousal index (all\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.01). NREM oxygen saturation and total arousals were not significantly different. Significant group \u00d7 AHI interactions (\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.05) indicated that these differences were more pronounced at lower AHI levels and attenuated with increasing severity. Among POSA patients, 32.0% had REM OSA (REM-AHI\u2009\u2265\u20092\u00d7 NREM-AHI), while nearly 70% of REM OSA exhibited POSA.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>POSA is highly prevalent and characterized by lower BMI and a more favorable sleep and oxygenation profile independent of AHI. Differences in POSA, although small, were more evident in milder disease and diminished with increasing severity. The overlap with REM OSA was asymmetric, with positional dependence more frequent in REM OSA than the converse. These findings highlight the heterogeneity of POSA and need for individualized management.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1007\/s11325-026-03755-3","type":"journal-article","created":{"date-parts":[[2026,7,4]],"date-time":"2026-07-04T10:55:27Z","timestamp":1783162527000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Analysis of positional obstructive sleep apnea features in 12,000 patients at a sleep center"],"prefix":"10.1007","volume":"30","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4885-5775","authenticated-orcid":false,"given":"C\u00edntia Felicio Adriano","family":"Rosa","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Karina Ang\u00e9lica Soto","family":"Chillcce","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5704-160X","authenticated-orcid":false,"given":"Michel Burihan","family":"Cahali","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marcela Souza","family":"Boldt","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0008-0211-6724","authenticated-orcid":false,"given":"Victor Henrique Dominiak","family":"Soares","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ordival Augusto","family":"Rosa","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Pedro Henrique Vicari","family":"Passos","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Matheus Roberto Schetz","family":"Alves","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Enrico Guido Oliveira","family":"Minniti","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jefferson Ernani","family":"Rodrigues","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Giuliana Rita Wolski","family":"Ribas","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2026,7,4]]},"reference":[{"issue":"3","key":"3755_CR1","doi-asserted-by":"publisher","first-page":"611","DOI":"10.1016\/j.mcna.2004.01.002","volume":"88","author":"C Guilleminault","year":"2004","unstructured":"Guilleminault C, Abad VC (2004) Obstructive sleep apnea syndromes. 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For this type of study formal consent is not required. The study was approved by the Research Ethics Committee of our institution (Hospital IPO, Curitiba, Brazil), with CAAE identification on Plataforma Brazil No. 69580723.0.0000.5529. There is no clinical trial registration number because this is not a clinical trial.","order":1,"name":"Ethics","label":"Ethics approval and consent to participate","group":{"name":"EthicsHeading","label":"Declarations"}},{"value":"The present study did not receive financial support from funding agencies or companies. Michel Burihan Cahali is a stockholder in the Brazilian company Biologix\n                      \u00ae\n                      , that markets a home sleep apnea test (not used in this study). Jefferson Ernani Rodrigues reports to be the CEO of Orthopedic Sleep\n                      \u00ae\n                      , which produces sleep-ergonomics products; this relationship is disclosed in accordance with journal policies. This study did not evaluate positional therapy or devices. All other authors declare no conflicts of interest.","order":2,"name":"Ethics","label":"Competing interests","group":{"name":"EthicsHeading","label":"Declarations"}},{"value":"Not applicable.","order":3,"name":"Ethics","label":"Authors\u2019 information","group":{"name":"EthicsHeading","label":"Declarations"}}],"article-number":"207"}}