Risk factors for unplanned reoperation after corrective surgery for adult spinal deformity

Abstract

Aims To determine the major risk factors for unplanned reoperations (UROs) following correc-tive surgery for adult spinal deformity (ASD) and their interactions, using machine learning -based prediction algorithms and game theory.Methods Patients who underwent surgery for ASD, with a minimum of two -year follow -up, were retro-spectively reviewed. In total, 210 patients were included and randomly allocated into train-ing (70% of the sample size) and test (the remaining 30%) sets to develop the machine learning algorithm. Risk factors were included in the analysis, along with clinical character-istics and parameters acquired through diagnostic radiology.Results Overall, 152 patients without and 58 with a history of surgical revision following surgery for ASD were observed; the mean age was 68.9 years (SD 8.7) and 66.9 years (SD 6.6), respec-tively. On implementing a random forest model, the classification of URO events resulted in a balanced accuracy of 86.8%. Among machine learning-extracted risk factors, URO, proximal junction failure (PJF), and postoperative distance from the posterosuperior corner of C7 and the vertical axis from the centroid of C2 (SVA) were significant upon Kaplan -Meier survival analysis.Conclusion The major risk factors for URO following surgery for ASD, i.e. postoperative SVA and PJF, and their interactions were identified using a machine learning algorithm and game theory. Clin-ical benefits will depend on patient risk profiles.