Turkish Translation, Validation, and Reliability Analysis of Pediatric Eosinophilic Esophagitis Symptom Severity Module Version 2.0

**Background:** Eosinophilic esophagitis (EoE) is characterized by esophageal dysfunction symptoms and eosinophil-predominant inflammation localized to the esophagus. Pediatric symptoms vary by age, from food bolus impaction and dysphagia in older children to nonspecific feeding difficulties (vomiting, regurgitation, feeding refusal) in infants and toddlers that can lead to failure to thrive. The Pediatric Eosinophilic Esophagitis Symptom Severity Module Version 2.0 (PEESv2.0) is a validated pediatric EoE symptom tool with two metrics: a self-report for children/teens aged 8–18 years and a parent proxy-report for children aged 2–18 years. No validated Turkish version existed prior to this study.

**Methods:** This was a multicenter methodological study of translation, cultural adaptation, and validation. The English PEESv2.0 was translated into Turkish in four standardized steps in cooperation with the Mapi Research Trust: (1) forward translation by two native Turkish speakers fluent in English; (2) backward translation by two native English speakers, with content validity assessed by 6 pediatric gastroenterology experts rating each item on a 4-point scale (1=not relevant to 4=highly relevant); (3) cognitive interviewing with 5 children and 5 parents; and (4) proofreading. Children aged 2–18 years with clinicopathologically diagnosed EoE (≥15 eosinophils/HPF on esophageal biopsy with symptoms of esophageal dysfunction) from 6 pediatric gastroenterology clinics were enrolled. Participants completed T-PEESv2.0 and repeated it 1 week later for test-retest reliability. An age-matched healthy control group was used for discriminant validity. Internal consistency was tested using Cronbach's alpha. Test-retest reliability was measured with intraclass correlation coefficient (ICC). Discriminant validity was evaluated by comparing patient and control group scores using independent samples t-test or Mann-Whitney U test.

**Key Results:** One hundred seventy-nine participants were enrolled (97 patients, 82 controls). The median age (IQR) was 9 (6.75) years for both groups; 60.9% were male. Fifty-eight parents completed T-PEESv2.0-parent by proxy and 70 patients completed T-PEESv2.0-children and teens. Cronbach's alpha coefficients were >0.70 for both questionnaires and all domains: for T-PEESv2.0-parent by proxy, frequency domain α=0.98, severity domain α=0.96, total metric α=0.95; for T-PEESv2.0-children and teens, frequency domain α=0.97, severity domain α=0.95, total metric α=0.95. ICC values for test-retest reliability were >0.70 for both metrics (0.94 for parent proxy, 0.95 for child self-report). For discriminant validity, all subscale and total scores were significantly higher in the patient group compared to controls (P<0.001 for each subscale). For T-PEESv2.0-parent by proxy: frequency score 34.09 vs 9.09, severity score 36.11 vs 7.29, total score 33.75 vs 7.69. For T-PEESv2.0-children and teens: frequency score 25.00 vs 4.54, severity score 22.22 vs 2.77, total score 26.25 vs 3.75. During content validity, items rated <4 points were revised; key revisions included changing "almost never" from "Hemen hemen hiç" to "Neredeyse hiç," "bad" from "Kötü" to "Şiddetli," and clarifying questions 11, 19, and 20 by specifying "other children" instead of "others." Cognitive interviewing led to revision of question 17's phrase "back up your throat" from "çikarir" (spits up) to "boğaziniza geri gelir" (come back to your throat).

**Clinical Implications:** T-PEESv2.0 is a valid and reliable Turkish-language tool for assessing pediatric EoE symptoms from both patient and parent perspectives. It can be used in clinical practice for objective symptom assessment and for research purposes in Turkish-speaking populations. The study's limitation is the lack of construct validity testing against another similar measure, as no validated Turkish pediatric EoE symptom score existed for comparison. The tool covers the full pediatric age range (2–18 years) through its two metrics and addresses the critical need for standardized, patient-reported outcome measures in Turkish EoE patients.