106. Predictive probability of the global alignment and proportion score for the development of mechanical failure following adult spinal deformity surgery in Asian patients

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BACKGROUND CONTEXT The global alignment and proportion (GAP) score is a recently established risk stratification model for mechanical failure (MF) following adult spinal deformity (ASD) surgery. However, the predictive ability of the GAP score is not well studied. PURPOSE This study aimed to validate the predictive probability of the GAP score in an Asian ASD patient cohort. STUDY DESIGN/SETTING This is a multicenter retrospective review of surgically treated ASD patients. PATIENT SAMPLE This study included 257 surgically treated ASD patients who had a minimum of 5 fused segments, completed a 2-year follow-up, and were selected by consecutive sampling (53 ± 19 years, females: 236 [92%]). OUTCOME MEASURES Development of MF (PJK, PJF, rod breakage, DJK, etc. Variables included age, gender, BMI, BMD, frailty, comorbidities, fusion level, UIV and LIV, revision, PSO, LIF, postoperative neurological deficit, spinal alignment, GAP score, Schwab-SRS type, surgical time, and blood loss). METHODS Comparisons of the immediate postoperative GAP scores between MF the and MF-free groups were performed. We evaluated the discriminative ability of the GAP score based on the area under the receiver operating characteristic curve (AUROC). The Cuzick test was performed to determine whether there is a trend between the GAP score and the incidence of MF or revision surgery. Univariate logistic regression analyses were performed to explore the associations between the GAP score and the incidence of MF or revision surgery. RESULTS No difference was observed in the GAP score between the MF and MF-free groups (MF vs MF-free; GAP: 5.9±3.3 vs 5.2±2.7, p=0.07). The Cuzick analysis showed no trend between the GAP score and the risk for MF or revision surgery. Likewise, the MF rate was not correlated with the GAP score, as shown by the ROC curve (AUC of 0.56 [95% CI 0.48–0.63], p=0.124). Univariate logistic regression confirmed no associations between the GAP score and the incidence of MF or revision surgery (MF; MD [moderately disproportioned]: OR: 0.6 [95% CI: 0.3-1.2], p=0.17, SD [severely disproportioned]: OR: 1.2 [95% CI: 0.6-2.3], p=0.69, revision surgery; MD: OR: 0.8 [95% CI: 0.2-2.8[, p=0.71, SD: OR: 1.2 [95% CI: 0.9-8.7], p=0.08). CONCLUSIONS In this multicenter study, in an Asian ASD patient cohort, the GAP score was not associated with the incidence of MF or revision surgery. Additional studies on the predictive ability of the GAP score in different patient cohorts are warranted. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.