Should Age-adjusted Realignment Goals Vary Based on Patient Frailty Status in Adult Spinal Deformity

Introduction: Frailty may be a better predictor of outcomes than age following ASD surgery. We sought to adjust the Sagittal Age-Adjusted Score(SAAS) to accommodate frailty in alignment considerations and increase the predictability of clinical outcomes and junctional failure.

Methods: Included: ASD patients with two-year(2Y) data. Frailty assessed by ASD modified Frailty Index (ASD-mFI). Two-year outcomes: proximal junctional kyphosis(PJK) and failure(PJF), major mechanical complications, and Smith et al ‘Best Clinical Outcome’(BCO), defined as ODI < 15 and SRS-Total>4.5 by 2Y. Linear regression analysis established a six-week(6W) score based on the SAAS component scores, and logistic regression analysis and conditional inference tree(CIT) analysis generated categorical thresholds. Multivariate analysis controlling for age, baseline deformity, and history of revision compared outcome rates. Thirty percent of the cohort was used as a random sample for internal validation.

Results: 828 patients included. Baseline frailty categories: 405(48.9%) Not Frail, 289(34.9%) Frail, 134(16.2%) Severely Frail. 44% of patients developed PJK, 10% PJF, 18% mechanical complications, 27% underwent reoperation, and 17% met BCO. When assessing the cohort as a whole, SAAS had correlation with development of PJK, PJF, but not mechanical complications, reoperation or meeting BCO. Regression analysis modifying SAAS based on frailty generated the following equation: Frailty-Adjusted SAAS(FAS) Score = 0.108*T1PA+0.162*PT-0.39*PI-LL-0.03*ASD-mFI-1.6771.
Significance between FAS categorical thresholds were found for PJK, PJF, mechanical complications, reoperation and meeting BCO by two years. Internal validation saw each outcome variable maintain significance between categories, with even greater odds for PJF(OR: 13.4, 4.7-38.3; p < .001).

Conclusion : Consideration of physiologic age, in addition to chronological age, may be beneficial in management of operative goals to maximize clinical outcomes while minimizing junctional failure. This combination enables the spine surgeon to fortify a surgical plan for even the most challenging patients undergoing adult spinal deformity corrective surgery.