Purposes: To determine the relationship between low body mass index (BMI) and the outcome of brace treatment in patients with adolescent idiopathic scoliosis (AIS).
Methods: 350 braced female AIS patients were included in this study. The baseline characteristics of the patient were recorded at their first visit, including age, Risser sign, digital skeletal age, BMI, curve pattern, and curve magnitude. Underweight was defined as lower than the 5th percentile of the sex- and age-specific BMI. The treatment was considered as a failure if the curve progressed more than 5°, or if patients underwent surgery. According to the final outcome of brace treatment, the cohort was divided into the success group and the failure group. A logistic regression model was created to determine the independent predictors of the bracing outcome.
Results: 24.5% (86/350) of the patients were identified as underweight at their initial visit, which was significantly higher than the rate of 13.1% (46/350) at the final follow-up (p < 0.001). At the initial visit of the patients, the rate of underweight was 17.6% (45/255) in the success group, which was significantly lower than the rate of 43.1% (41/95) in the failure group (p < 0.001). Logistic regression analysis showed that low BMI was significantly associated with bracing failure (p < 0.001).
Conclusion: The low BMI could be predictive of bracing failure in AIS patients, which should be taken into account when surgeons prescribe brace treatment to such patients.
Keywords: Body mass index; Brace treatment; Predict; Scoliosis.