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Bracing in Adolescent Idiopathic Scoliosis Trial (BrAIST): Development and Validation of a Prognostic Model in Untreated Adolescent Idiopathic Scoliosis Using the Simplified Skeletal Maturity System

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Abstract

Study Design

Prognostic study and validation using prospective clinical trial data.

Objective

To derive and validate a model predicting curve progression to ≥45° before skeletal maturity in untreated patients with adolescent idiopathic scoliosis (AIS).

Summary of Background Data

Studies have linked the natural history of AIS with characteristics such as sex, skeletal maturity, curve magnitude, and pattern. The Simplified Skeletal Maturity Scoring System may be of particular prognostic utility for the study of curve progression. The reliability of the system has been addressed; however, its value as a prognostic marker for the outcomes of AIS has not. The BrAIST trial followed a sample of untreated AIS patients from enrollment to skeletal maturity, providing a rare source of prospective data for prognostic modeling.

Methods

The development sample included 115 untreated BrAIST participants. Logistic regression was used to predict curve progression to ≥45° (or surgery) before skeletal maturity. Predictors included the Cobb angle, age, sex, curve type, triradiate cartilage, and skeletal maturity stage (SMS). Internal and external validity was evaluated using jackknifed samples of the BrAIST data set and an independent cohort (n = 152). Indices of discrimination and calibration were estimated. A risk classification was created and the accuracy evaluated via the positive (PPV) and negative predictive values (NPV).

Results

The final model included the SMS, Cobb angle, and curve type. The model demonstrated strong discrimination (c-statistics 0.89–0.91) and calibration in all data sets. The classification system resulted in PPVs of 0.71–0.72 and NPVs of 0.85–0.93.

Conclusions

This study provides the first rigorously validated model predicting a short-term outcome of untreated AIS. The resultant estimates can serve two important functions: 1) setting benchmarks for comparative effectiveness studies and 2) most importantly, providing clinicians and families with individual risk estimates to guide treatment decisions.

Level of Evidence

Level 1, prognostic.

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Author information

Authors and Affiliations

  1. Department of Orthopaedics and Rehabilitation, University of Iowa, 01048 JPP, 200 Hawkins Drive, Iowa City, IA, 52242, USA

    Lori A. Dolan PhD

  2. University of Iowa, 200 Hawkins Drive, Iowa City, IA, 52242, USA

    Stuart L. Weinstein MD & Tyler O. Farber BS

  3. University of Virginia Children’s Hospital, 2270 Ivy Road, Charlottesville, VA, 22903, USA

    Mark F. Abel MD

  4. UPMC Children’s Hospital of Pittsburgh, 4401 Penn Ave, Pittsburgh, PA, 15224, USA

    Patrick P. Bosch MD

  5. Washington University Orthopaedics in St. Louis, 1 Children’s Place, St. Louis, MO, 63110, USA

    Matthew B. Dobbs MD

  6. Oregon Health & Science University, 3181 S.W. Sam Jackson Park Rd, Portland, OR, 97239-3098, USA

    Matthew F. Halsey MD

  7. Boston Children’s Hospital, 300 Longwood Ave, Boston, MA, 02115, USA

    M. Timothy Hresko MD

  8. Seattle Children’s Hospital, 4800 Sand Point Way NE, Seattle, WA, 98105, USA

    Walter F. Krengel MD

  9. Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH, 45229, USA

    Charles T. Mehlman DO, MPH

  10. University of North Carolina at Chapel Hill, 130 Mason Farm Road, Chapel Hill, NC, 27599, USA

    James O. Sanders MD

  11. Children’s Mercy Kansas City, 2401 Gillham Rd, Kansas City, MO, 64108, USA

    Richard M. Schwend MD

  12. Nemours/Alfred I. DuPont Hospital for Children, 1600 Rockland Rd, Wilmington, DE, 19803, USA

    Suken A. Shah MD

  13. 3851 Katella Avenue, Suite 255, Los Alamitos, CA, 90720, USA

    Kushagra Verma MD, MS

Authors
  1. Lori A. Dolan PhD
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  2. Stuart L. Weinstein MD
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  14. Kushagra Verma MD, MS
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Corresponding author

Correspondence to Lori A. Dolan PhD.

Additional information

Author disclosures: LAD (grants from NIH/NIAMS, Canadian Institutes of Health Research, Shriner’s Hospitals for Children, Children’s Miracle Network, and Joan and Phill Berger Charitable Fund; other from Estate of Herb and Nancy Townsend, during the conduct of the study; grants from Pediatric Orthopedic Society of North America [POSNA], consulting agreement with Green Sun Medical via the University of Iowa, outside the submitted work), SLW (grants from NIH/NIAMS, Canadian Institutes of Health Research, Shriner’s Hospitals for Children, Children’s Miracle Network, and Joan and Phill Berger Charitable Fund; other from Estate of Herb and Nancy Townsend, during the conduct of the study), MFA (grants from NIH/NIAMS, during the conduct of the study), PPB (none), MBD (none), TOF (none), MFH (none), MTH (other from Boston Orthotics and Prosthetic, other from NuVasive, outside the submitted work; and member, board of directors, POSNA, committee chair, Scoliosis Research Society), WFK (none), CTM (grants from NIH/NIAMS, University of Iowa, during the conduct of the study; personal fees from Hawaii Orthopaedic Association, Albert Einstein Hospital Sao Paulo, Brazil, Denver Children’s Hospital, University of Colorado, Michigan State University, and Vanderbilt University; and other from US News & World Report, Best Children’s Hospital; nonfinancial support from Journal of Pediatric Orthopaedics, Journal of Orthopaedic Trauma, Journal of Children’s Orthopaedics, and the Spine Journal; personal fees from Oakstone Medial Publishing, outside the submitted work), JOS (grants from University of Iowa, SRS and POSNA, outside the submitted work), JOS (grants from Joan and Phill Berger Charitable Fund, during the conduct of the study; grants from SRS and POSNA, outside the submitted work; and committee chair, POSNA, SRS Stock ownership, Abbot Labs, Abbvie, GE, Green Sun Medical), RMS (other from POSNA and American Academy of Pediatrics; personal fees, nonfinancial support, and other from Medtronic; other from Project Perfect World, outside the submitted work), SAS (personal fees from DePuy Synthes Spine, grants from Setting Scoliosis Straight Foundation, outside the submitted work), KV (personal fees from Spine Mark, outside the submitted work).

Human subjects’ research approval for BrAIST was obtained from the local boards of all participating centers; approval for collection and use of additional data was obtained from the University of Iowa and Nemours/Alfred I. duPont Hospital for Children.

Financially supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health (R21AR049587 and R01AR052113); the Children’s Miracle Network, the Canadian Institutes of Health Research (FRN-81050), the Shriners Hospitals for Children, the University of Rochester, Children’s Mercy Kansas City, the Joan and Phill Berger Charitable Fund, and the Estate of Herb and Nancy Townsend.

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Dolan, L.A., Weinstein, S.L., Abel, M.F. et al. Bracing in Adolescent Idiopathic Scoliosis Trial (BrAIST): Development and Validation of a Prognostic Model in Untreated Adolescent Idiopathic Scoliosis Using the Simplified Skeletal Maturity System. Spine Deform 7, 890–898 (2019). https://doi.org/10.1016/j.jspd.2019.01.011

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