Development of validated computer-based preoperative predictive model for proximal junction failure (PJF) or clinically significant PJK with 86% accuracy based on 510 ASD patients with 2-year follow-up

Justin K. Scheer, Joseph A. Osorio, Justin S. Smith, Frank Schwab, Virginie Lafage, Robert A. Hart, Shay Bess, Breton Line, Bassel G. Diebo, Themistocles S. Protopsaltis, Amit Jain, Tamir Ailon, Douglas C. Burton, Christopher I. Shaffrey, Eric Klineberg, Christopher P. Ames

Research output: Contribution to journalArticlepeer-review

88 Scopus citations

Abstract

Study Design. A retrospective review of large, multicenter adult spinal deformity (ASD) database. Objective. The aim of this study was to build a model based on baseline demographic, radiographic, and surgical factors that can predict clinically significant proximal junctional kyphosis (PJK) and proximal junctional failure (PJF). Summary of Background Data. PJF and PJK are significant complications and it remains unclear what are the specific drivers behind the development of either. There exists no predictive model that could potentially aid in the clinical decision making for adult patients undergoing deformity correction. Methods. Inclusion criteria: age -18 years, ASD, at least four levels fused. Variables included in the model were demographics, primary/revision, use of three-column osteotomy, upper-most instrumented vertebra (UIV)/lower-most instrumented vertebra (LIV) levels and UIV implant type (screw, hooks), number of levels fused, and baseline sagittal radiographs [pelvic tilt (PT), pelvic incidence and lumbar lordosis (PI-LL), thoracic kyphosis (TK), and sagittal vertical axis (SVA)]. PJK was defined as an increase from baseline of proximal junctional angle -208 with concomitant deterioration of at least one SRS-Schwab sagittal modifier grade from 6 weeks postop. PJF was defined as requiring revision for PJK. An ensemble of decision trees were constructed using the C5.0 algorithm with five different bootstrapped models, and internally validated via a 70 : 30 data split for training and testing. Accuracy and the area under a receiver operator characteristic curve (AUC) were calculated. Results. Five hundred ten patients were included, with 357 for model training and 153 as testing targets (PJF: 37, PJK: 102). The overall model accuracy was 86.3% with an AUC of 0.89 indicating a good model fit. The seven strongest (importance ≥0.95) predictors were age, LIV, pre-operative SVA, UIV implant type, UIV, pre-operative PT, and pre-operative PI-LL. Conclusion. A successful model (86% accuracy, 0.89 AUC) was built predicting either PJF or clinically significant PJK. This model can set the groundwork for preop point of care decision making, risk stratification, and need for prophylactic strategies for patients undergoing ASD surgery.

Original languageEnglish (US)
Pages (from-to)E1328-E1335
JournalSpine
Volume41
Issue number22
DOIs
StatePublished - Nov 15 2016

Keywords

  • Adult spinal deformity
  • Predictive modeling
  • Proximal junctional failure
  • Proximal junctional kyphosis
  • Sagittal malalignment
  • Scoliosis

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Clinical Neurology

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