Spine Surgeon NYU School of Medicine New Canaan, CT, US
Introduction: As many patients requiring spine surgery are elder and often frail, restoration of alignment targets may differ. There is paucity in literature on whether different frailty and deformity states may warrant a different level of surgical invasiveness.
Methods: Operative ASD patients were included and categorized by Frailty into: Not Frail (NF), and Frail (F) and stratified by PILL as Severe deformity (Sev): >20, and Low (Low): < 20. 4 groups were formed: NF Low, F Low, NF Sev, F Sev. Thresholds for invasiveness level and cost utility were found through conditional inference tree (CIT) machine learning. Costs were calculated using the PearlDiver database, with QALY being calculated from SF6D.
Results: 381 patients were groups as: 44% NF Low, 19% NF Sev, 13% F Low, 20% F Sev. Higher costs for frail groups is likely due to an increased rate of revisions (p= < .001). The QALY gained by 2Y was: NF Low-.14, F Low-.22, NF Sev-.15, F Sev-.28 (p < .01). Despite higher surgical costs for F groups, the greater amount of QALY gained resulted in a justifiable cost utility by 2Y compared with NF groups (NF Low- $538,812 F Low- $490,907, NF Sev- $647,801, F Sev- $384,596). CIT found cutoffs between invasiveness and cost utility:37 for NF LM, 23 for F LM.
Conclusion : Cost analysis shows cost utility is at least for frail patients across both low and high degrees of deformity. Higher surgical costs, including higher rates of complications, by 2 years for frail patients are offset by the quality-adjusted life years gained by 2 years. When looking at surgical invasiveness, a lower degree of surgical invasiveness for frail patients maintains cost utility comparable to not frail patient. It is important to note this is a parabolic relationship and severe frailty has substantially greater surgical costs and lower cost-utility.
