{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,13]],"date-time":"2026-08-13T09:26:49Z","timestamp":1786613209751,"version":"build-2736575974"},"reference-count":30,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2026,8,13]],"date-time":"2026-08-13T00:00:00Z","timestamp":1786579200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Diagnostics"],"abstract":"<jats:p>Background\/Objectives: Frailty is increasingly recognized as a clinically relevant marker of reduced physiological reserve in surgical oncology. The modified 5-item frailty index (mFI-5) is simple and practical, but its clinical significance in oral squamous cell carcinoma (OSCC) remains incompletely defined. This study evaluated the association between mFI-5-defined frailty and postoperative complications, especially postoperative delirium, as well as survival outcomes in patients undergoing surgery for OSCC. Methods: We retrospectively analyzed 127 patients who underwent surgical resection for OSCC with postoperative high care unit (HCU) management between 2013 and 2021. Frailty was defined as an mFI-5 score of \u22652. Clinical characteristics, postoperative outcomes, HCU stay, length of hospital stay, overall survival (OS), and disease-free survival (DFS) were compared between frail and non-frail groups. Univariable logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for postoperative complications. An exploratory multivariable logistic regression analysis for postoperative delirium was performed using age \u226565 years and sex as covariates. Delirium was retrospectively assessed from clinical documentation considered consistent with DSM-5 criteria. Results: Twenty-one patients (16.5%) were classified as frail. Postoperative delirium occurred more frequently in frail patients than in non-frail patients (42.9% vs. 19.8%; p = 0.023). In a multivariable logistic regression model adjusted for age \u226565 years and sex, mFI-5-defined frailty was significantly associated with postoperative delirium (adjusted OR, 3.07; 95% CI, 1.08\u20138.60; p = 0.035). No significant association was observed for pneumonia, surgical site infection, or free-flap reoperation. Frailty was not significantly associated with HCU stay, length of hospital stay, OS, or DFS. Conclusions: mFI-5-defined frailty was associated with postoperative delirium but not with survival outcomes in this OSCC cohort. Because this retrospective study was limited by sample size, comorbidity-driven mFI-5 scoring, non-standardized delirium screening, and potential residual confounding, mFI-5 should be interpreted as a convenient screening marker rather than a stand-alone predictor. Comprehensive perioperative assessment incorporating frailty, nutrition, sarcopenia, cognition, tumor burden, and treatment-related factors may better identify patients at risk.<\/jats:p>","DOI":"10.3390\/diagnostics16162551","type":"journal-article","created":{"date-parts":[[2026,8,13]],"date-time":"2026-08-13T08:06:16Z","timestamp":1786608376000},"page":"2551","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Modified 5-Item Frailty Index Is Associated with Postoperative Delirium but Not Survival in Patients Undergoing Surgery for Oral Squamous Cell Carcinoma"],"prefix":"10.3390","volume":"16","author":[{"given":"Kenji","family":"Yamagata","sequence":"first","affiliation":[{"name":"Department of Oral and Maxillofacial Surgery, Kochi Medical School, Kochi University, 185-1 Kohasu, Oko-Cho, Nankoku 783-8505, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Satoshi","family":"Fukuzawa","sequence":"additional","affiliation":[{"name":"Department of Oral and Maxillofacial Surgery, University of Tsukuba Hospital, Tsukuba 305-8576, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shohei","family":"Takaoka","sequence":"additional","affiliation":[{"name":"Department of Oral and Maxillofacial Surgery, University of Tsukuba Hospital, Tsukuba 305-8576, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9345-4153","authenticated-orcid":false,"given":"Jumpei","family":"Shirakawa","sequence":"additional","affiliation":[{"name":"Department of Oral and Maxillofacial Surgery, Kochi Medical School, Kochi University, 185-1 Kohasu, Oko-Cho, Nankoku 783-8505, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kie","family":"Nakatani","sequence":"additional","affiliation":[{"name":"Department of Oral and Maxillofacial Surgery, Kochi Medical School, Kochi University, 185-1 Kohasu, Oko-Cho, Nankoku 783-8505, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eri","family":"Sasabe","sequence":"additional","affiliation":[{"name":"Department of Oral and Maxillofacial Surgery, Kochi Medical School, Kochi University, 185-1 Kohasu, Oko-Cho, Nankoku 783-8505, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yukio","family":"Yoshioka","sequence":"additional","affiliation":[{"name":"Department of Oral and Maxillofacial Surgery, Kochi Medical School, Kochi University, 185-1 Kohasu, Oko-Cho, Nankoku 783-8505, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0740-8490","authenticated-orcid":false,"given":"Naomi","family":"Kanno","sequence":"additional","affiliation":[{"name":"Department of Oral and Maxillofacial Surgery, University of Tsukuba Hospital, Tsukuba 305-8576, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fumihiko","family":"Uchida","sequence":"additional","affiliation":[{"name":"Department of Oral and Maxillofacial Surgery, University of Tsukuba Hospital, Tsukuba 305-8576, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"M146","DOI":"10.1093\/gerona\/56.3.M146","article-title":"Frailty in older adults: Evidence for a phenotype","volume":"56","author":"Fried","year":"2001","journal-title":"J. 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