Optimizing surgical timing: evaluating disability, frailty, and deformity severity thresholds in adult spinal deformity

BACKGROUND CONTEXT: Adult spinal deformity is a complex condition with a challenging demographic that often has high frailty, disability, and deformity at the time of surgical correction. Thresholds at which there is a point of diminishing returns can help guide patients and surgical decision-making. PURPOSE: To assess if there is a threshold of baseline disability, beyond which the patient-reported outcomes after surgical correction of ASD are adversely impacted. STUDY DESIGN/SETTING: Retrospective cohort analysis of a prospectively collected single-center ASD database. PATIENT SAMPLE: ASD. OUTCOME MEASURES: Disability. METHODS: We included primary operative ASD patients with a 2-year follow-up. Patients were evaluated based on baseline deformity in pelvic tilt (PT), pelvic incidence to lumbar lordosis mismatch (PI-LL), and T1 pelvic angle (TPA). The modified adult spinal deformity frailty index (mASD-FI) was utilized to evaluate patients based on frailty score. Disability was assessed using the Oswestry disability index (ODI). The primary outcome was the difference in ODI from the baseline to the last follow-up. Multivariable logistic regression and conditional inference tree (CIT) machine learning were used to evaluate thresholds associated with the greatest increase in 2Y ODI from baseline. RESULTS: A total of 289 patients met inclusion, with a mean age of 60±15, 80% female, BMI 27±6 kg/m2, CCI 1.7±1.7, mASD-FI 6.7±4.8. At baseline, ODI was 42±17, which improved at 2Y to 24±19. Preoperative PT was 23±10, PI-LL was 13±20, and TPA was 20±11.8. CIT analysis determined independent thresholds for baseline disability of >35 for ODI as the threshold at which improvement of ODI at 2Y started diminishing. Similarly, baseline mASD-FI of >6.5, PT > 19, PI-LL >20, and TPA >16 were found as thresholds for maximal improvement of ODI at 2Y (all p<.01). In patients with BL ODI between 18-34, mASD-FI of <5 was found to be associated with greater disability improvement. Those with BL ODI >44 and <74 found mASD-FI of <8 to be predictive of greater return of baseline disability (all p<.05). CONCLUSIONS: We evaluated the intricate interplay between patient disability, frailty, and the severity of deformity to ascertain the critical thresholds at which surgical interventions start to yield diminishing returns. These thresholds can help guide patient decision-making. FDA Device/Drug Status: This abstract does not discuss or include any applicable devices or drugs.

Duke Scholars

Author Christopher Ignatius Shaffrey Orthopaedic Surgery

Author Peter Passias Orthopaedic Surgery