Low Body Mass Index Levels and Idiopathic Scoliosis in Korean Children: A Cross-Sectional Study

Background: The prevalence of idiopathic scoliosis is rapidly increasing in Korean children, but research on the disorder is limited compared to that in other countries. Accordingly, in the present study, we aimed to investigate the relationship between idiopathic scoliosis and body mass index (BMI) levels in Korean children. Methods: This cross-sectional study enrolled elementary school students and middle school first graders in the Capital Area in Korea. The participants underwent body composition measurements and screening for idiopathic scoliosis. Idiopathic scoliosis was defined as a Cobb angle of ≥10°. The students were classified into three groups—the severely underweight (SUW: BMI < 16 kg/m(2)) group, the underweight group (UW: 16 ≤ BMI < 18.5 kg/m(2)), and the normal weight group (NW: 18.5 ≤ BMI < 25 kg/m(2)) to compare the risk of idiopathic scoliosis across BMI levels. Results: The final cohort comprised 1375 participants. The odds ratio (OR) of idiopathic scoliosis was 0.69 (95% confidence interval (CI): 0.50–0.94) and 0.66 (95% CI: 0.49–0.89) for the UW and the NW groups, respectively, with the SUW group as the reference. This shows that the risk decreased significantly by 31% and 34% in the UW and the NW groups, respectively. After controlling for age and sex, the corresponding ORs were 0.72 (95% CI: 0.52–0.98) and 0.70 (95% CI: 0.51–0.96), and the risk significantly decreased by 28% and 30% in the UW and the NW groups, respectively. Conclusions: Low body weight is closely associated with spinal deformity and idiopathic scoliosis.