Can curve characteristics predict severe progression in night-time bracing in adolescent idiopathic scoliosis?

To identify predictors for different severities of progression in Adolescent Idiopathic Scoliosis (AIS) patients undergoing night-time brace treatment. Patients with AIS, prescribed a nighttime brace between 2006 and 2023, with an initial curve angle of 20-45o, and Risser 0–3 were retrospectively included. Patients were grouped by progression: no progression (< 5o), mild (5-10o), moderate (11-20o), or severe (> 20o). We assessed variables including coronal deformity angular ratio (C-DAR), in-brace correction (IBC%), and curve type. Multinomial logistic regression assessed associations between curve characteristics and progression severity. Progression <5o was used for reference. An OR of less than 1 indicates lower risk of progression. We included 285 patients with a mean age of 13.3 ± 1.3 years and initial curve size of 36°±7°; 80% of the cohort was female; 68% had thoracic curve types. Younger age was the strongest predictor of progression, differentiating severe and moderate progression from mild cases (OR 0.44 and 0.61). Thoracic curve type was the next influential parameter, associated with severe and mild progression (OR 2.57 and 2.26). Higher initial curve size predicted moderate progression only (OR 1.13). Female sex and higher IBC were protective variables, reducing the odds of mild and severe progression (Female: OR 0.38 and 0.29; IBC: OR 0.96 and 0.98). C-DAR showed no significant association with progression. Male sex, low IBC, and thoracic curve type predicted progression, did not differentiate well between the mild and severe progression. Younger age predicted moderate and severe progression, but not mild. Skeletal maturity remains the crucial consideration for risk assessment.