{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,10]],"date-time":"2026-07-10T15:13:07Z","timestamp":1783696387708,"version":"3.55.0"},"reference-count":33,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2026,7,10]],"date-time":"2026-07-10T00:00:00Z","timestamp":1783641600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Children"],"abstract":"<jats:p>Background\/Objectives: Preoperative discrimination of complicated appendicitis in children remains challenging but crucial for timely surgical decision-making and perioperative management. We aimed to develop a simple, clinically applicable scoring system for preoperative risk stratification of complicated appendicitis in children. Methods: This retrospective single-center study included children aged 5 to &lt;16 years who underwent emergency appendectomy between 2015 and 2024. Complicated appendicitis was defined as gangrene, perforation, or intra-abdominal abscesses on intraoperative or pathological evaluation. Literature-based prespecified predictors included body temperature \u2265 38.0 \u00b0C, presence of periappendicular fluid, serum sodium level &lt; 135 mEq\/L, white blood cell (WBC) count &gt; 12,000\/\u03bcL, and C-reactive protein (CRP) level \u2265 3.0 mg\/dL. A multivariable logistic regression model using Firth\u2019s penalized likelihood was developed and internally validated using bootstrap resampling. An additive scoring system was derived from the final model. Results: Among 301 patients, 102 (33.9%) had complicated appendicitis. Based on the Firth penalized multivariable model, integer point values were assigned in proportion to the regression coefficients. Serum sodium level &lt; 135 mEq\/L and CRP level \u2265 3.0 mg\/dL assigned 2 points each; body temperature \u2265 38.0 \u00b0C, presence of periappendicular free fluid, and WBC count &gt; 12,000\/\u03bcL assigned 1 point each. The scoring system (range, 0\u20137) demonstrated good discrimination (area under the receiver operating characteristic curve, 0.880; 95% confidence interval, 0.840\u20130.920), minimal optimism, and good calibration. Stratification into low-, intermediate-, and high-risk categories showed an increasing prevalence of complicated appendicitis. Conclusions: This simple preoperative scoring system enables reliable and clinically interpretable risk stratification for complicated appendicitis in children aged 5 to &lt;16 years and may support early decision-making in routine pediatric surgical practice.<\/jats:p>","DOI":"10.3390\/children13070913","type":"journal-article","created":{"date-parts":[[2026,7,10]],"date-time":"2026-07-10T14:14:25Z","timestamp":1783692865000},"page":"913","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["A Simple Preoperative Scoring System for Risk Stratification of Complicated Appendicitis in Children"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5006-2507","authenticated-orcid":false,"given":"Yohei","family":"Sanmoto","sequence":"first","affiliation":[{"name":"Department of Pediatric Surgery, University of Tsukuba Hospital, Tsukuba 305-8576, Japan"},{"name":"Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba 305-8575, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-8322-0474","authenticated-orcid":false,"given":"Masanaga","family":"Matsumoto","sequence":"additional","affiliation":[{"name":"Department of Pediatric Surgery, University of Tsukuba Hospital, Tsukuba 305-8576, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kouji","family":"Masumoto","sequence":"additional","affiliation":[{"name":"Department of Pediatric Surgery, University of Tsukuba Hospital, Tsukuba 305-8576, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2342","DOI":"10.1016\/j.jpedsurg.2011.09.030","article-title":"Does age affect the outcomes and management of pediatric appendicitis?","volume":"46","author":"Lee","year":"2011","journal-title":"J. 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