title: Initial Cobb angle reduction velocity following bracing as a new predictor for curve progression in adolescent idiopathic scoliosis.
abstract: OBJECTIVE
  The initial correction rate (ICR) has been widely used as a predictor for curve progression in adolescent idiopathic scoliosis (AIS) undergoing bracing treatment. We proposed a new parameter, the initial Cobb angle reduction velocity (ARV), for prediction of curve progression. The purpose of this study was to identify whether the initial ARV was a more effective predictor than ICR for curve progression in AIS patients undergoing brace treatment, and to evaluate the ideal cut-off point of initial ARV for prediction of curve progression.
  
  
  METHODS
  This was a retrospective cohort study on AIS girls receiving standardized bracing treatment regularly followed up every 3-6 months. Standardized SRS criteria for bracing study were utilized in the case selection. The demographic data, maturity status and Cobb angle of each visit were recorded. The initial ARV and ICR were identified. Patients were divided into progressive (≥6°) and non-progressive (<6°) groups based on their final bracing outcome. Differences between two groups were identified and logistic regression analysis was applied to compare the predictive values of initial ARV and ICR for curve progression during bracing treatment.
  
  
  RESULTS
  Seventy-six patients were included in the non-progressive group and 19 in the progressive group. Significant differences between non-progressive and progressive groups were found in terms of initial ARV (12.8 ± 21.4°/year vs -5.4 ± 15.2°/year, P = 0.001) and ICR (12.1 ± 20.7 % vs -5.8 ± 18.0 %, P = 0.001). The logistic regression analysis revealed that age at initial visit (OR 1.742, P = 0.043) and initial ARV (OR 1.057, P = 0.002) had higher predictive values than ICR (P = 0.601) for curve progression in braced AIS girls. The ideal cut-off point of initial ARV was 10°/year (OR 8.959, P = 0.005) for the prediction of curve progression.
  
  
  CONCLUSIONS
  The initial Cobb angle reduction velocity serves as a better predictor for curve progression than initial correction rate in braced AIS patients with follow-up interval of 3-6 months. At the second visit following bracing prescription, those AIS patients with reduction velocity in Cobb angle lower than 10°/year have significantly higher risk of curve progression.
authors.affiliation: Spine Surgery, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Zhongshan Road No. 321, Nanjing, 210008, China.|Joint Scoliosis Research Center of the Chinese University of Hong Kong and Nanjing University, Nanjing, China.
authors.forename: Saihu
authors.initials: S
authors.lastname: Mao
authors.affiliation: Spine Surgery, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Zhongshan Road No. 321, Nanjing, 210008, China.|Joint Scoliosis Research Center of the Chinese University of Hong Kong and Nanjing University, Nanjing, China.
authors.forename: Benlong
authors.initials: B
authors.lastname: Shi
authors.affiliation: Spine Surgery, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Zhongshan Road No. 321, Nanjing, 210008, China.|Joint Scoliosis Research Center of the Chinese University of Hong Kong and Nanjing University, Nanjing, China.
authors.forename: Leilei
authors.initials: L
authors.lastname: Xu
authors.affiliation: Department of Orthopaedics and Traumatology, Chinese University of Hong Kong, Hong Kong, China.|Joint Scoliosis Research Center of the Chinese University of Hong Kong and Nanjing University, Nanjing, China.
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Orthopaedics and Traumatology, Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Alec Lik Hang
authors.initials: AL
authors.lastname: Hung
authors.affiliation: Department of Orthopaedics and Traumatology, Chinese University of Hong Kong, Hong Kong, China.|Joint Scoliosis Research Center of the Chinese University of Hong Kong and Nanjing University, Nanjing, China.
authors.forename: Tsz Ping
authors.initials: TP
authors.lastname: Lam
authors.affiliation: Department of Orthopaedics and Traumatology, Chinese University of Hong Kong, Hong Kong, China.|Joint Scoliosis Research Center of the Chinese University of Hong Kong and Nanjing University, Nanjing, China.
authors.forename: Fiona Wai Ping
authors.initials: FW
authors.lastname: Yu
authors.affiliation: Department of Orthopaedics and Traumatology, Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Kwong Man
authors.initials: KM
authors.lastname: Lee
authors.affiliation: Department of Orthopaedics and Traumatology, Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Bobby Kin Wah
authors.initials: BK
authors.lastname: Ng
authors.affiliation: Department of Orthopaedics and Traumatology, Chinese University of Hong Kong, Hong Kong, China.|Joint Scoliosis Research Center of the Chinese University of Hong Kong and Nanjing University, Nanjing, China.
authors.forename: Jack Chun Yiu
authors.initials: JC
authors.lastname: Cheng
authors.affiliation: Spine Surgery, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Zhongshan Road No. 321, Nanjing, 210008, China.|Joint Scoliosis Research Center of the Chinese University of Hong Kong and Nanjing University, Nanjing, China.
authors.forename: Zezhang
authors.initials: Z
authors.lastname: Zhu
authors.affiliation: Spine Surgery, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Zhongshan Road No. 321, Nanjing, 210008, China. scoliosis2002@sina.com.|Joint Scoliosis Research Center of the Chinese University of Hong Kong and Nanjing University, Nanjing, China. scoliosis2002@sina.com.
authors.forename: Yong
authors.initials: Y
authors.lastname: Qiu
mesh_terms: D000293:Adolescent; D000367:Age Factors; D001915:Braces; D002648:Child; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016015:Logistic Models; D008297:Male; D011859:Radiography; D012189:Retrospective Studies; D012600:Scoliosis / Q000000981:diagnostic imaging* / Q000628:therapy*; D013997:Time Factors
keywords: Adolescent idiopathic scoliosis; Brace; Curve progression; Initial Cobb angle reduction velocity; Initial correction rate