목적: Pediatric obstructive sleep apnea (OSA) affects 2–5% of children, causing behavioral issues, growth failure, and reduced quality of life. Although polysomnography (PSG) is the diagnostic gold standard, it is time-consuming, costly, and uncomfortable. This study aimed to identify demographic and physical examination factors associated with PSG parameters, including the apnea- hypopnea index (AHI), and to assess differences based on obesity and age group (preschool vs. school-aged children). 방법:We retrospectively reviewed pediatric patients aged ≤12 years with OSA symptoms who underwent level I PSG between November 2018 and January 2025. Patients with craniofacial abnormalities or prior adenoidectomy/tonsillectomy were excluded. The size of the adenoids relative to the nasopharynx was measured using the Fujioka method, and the tonsil grade was assessed based on the sum of both tonsil sizes according to the Friedman tonsil grading system. Pearson’s or Spearman’s correlation tests were appropriately used to evaluate the associations between PSG parameters and factors such as age, tonsil grade, adenoid ratio, body mass index (BMI), neck circumference, and waist circumference. Multiple regression analysis was used to predict AHI, and subgroup analyses compared BMI (<85th vs. ≥85th percentile) and age groups (<6 vs. ≥6 years). Analyses were performed with SPSS 21.0 (IBM Corp., Armonk, NY, USA). 결과:The study was conducted on a total of 192 patients (122 boys and 70 girls). Among the study population, AHI, oxygen desaturation index (ODI), apnea index (AI), hypopnea index (HI), and cumulative time spent below 90% oxygen saturation (CT90) showed positive correlations with age, tonsil grade, BMI, neck circumference, and waist circumference, while the lowest oxygen saturation demonstrated negative correlations with tonsil grade, BMI, neck circumference, and waist circumference. The adenoid ratio did not show statistically significant correlations with the aforementioned PSG parameters. In multiple regression analysis, BMI (β = 1.315, p < 0.05) and tonsil grade (β = 2.346, p < 0.05) were identified as significant predictors of AHI. In subgroup analyses, tonsil grade (β = 1.061, p < 0.05) was a significant predictor of AHI in the underweight–normal weight group, while both BMI (β = 1.580, p < 0.05) and tonsil grade (β = 3.942, p < 0.05) were significant predictors in the overweight–obese group. Based on age, tonsil grade (β = 2.887, p < 0.05) and BMI (β = 1.418, p < 0.05) were significant predictors of AHI in preschool-aged children, whereas BMI (β = 1.507, p < 0.05) was the only significant predictor in school-aged children. 결론:BMI and tonsil grade were identified as key predictors of AHI in pediatric OSA, with their impact varying based on BMI and age subgroups. In the underweight–normal weight group, tonsil grade was a significant predictor of AHI. In the overweight–obese group, both BMI and tonsil grade were identified as key predictors, indicating that BMI becomes a significant factor in the presence of excess weight. Among preschool-aged children, AHI was significantly associated with both tonsil grade and BMI, whereas in school-aged children, BMI emerged as the primary predictor of AHI.