24 - Comparison of a Modified Adult Spinal Deformity Frailty Index to Previously Established Indices

Introduction: The comparison of various frailty indices and their ability to predict complications after ASD surgery has not been investigated.

Purpose: Assessing the different frailty indices used in ASD surgery to predict complication outcomes demonstrated the similar predictability of the modified ASD frailty index by Passias et al for any and major complications, as well as length of stay. The mFI-ASD showed increased benefit in the severely frail population for both infection and reoperation rates.
The mFI-ASD has better predictive in certain complications compared to FI-ASD and the ACS-NSQIP 5-factor mFI.

Design: Retrospective review of an ASD database

Methods: Operative ASD patients with baseline (BL) and 1-year (1Y) data were included. Three frailty indices were used for comparison: Passias et al modified ASD frailty index (mFI), Miller et al ASD frailty index (FI-ASD), and the ACS-NSQIP 5-Factor frailty index (ACS-FI). Patients were stratified into not frail (NF), frail (F), and severely frail (SF). Trends in baseline factors were analyzed using ANOVA between NF, F, and SF patients according to mFI-ASD. Associations of the indices with complications, reoperations, and LOS were compared using logistic and linear regression analyses.

Results: 509 ASD patients were included. An increase in each frailty index was associated with higher odds of any or major complications, and a longer LOS. The likelihood of reoperation was only higher in the F/SF groups according to the mFI and FI-ASD, along with likelihood of implant failure. A higher likelihood of infections was seen in F and SF groups for the mFI. When compared to NF, SF of each index had a higher likelihood of any or major complications, and longer LOS. SF, by mFI and FI-ASD, had higher odds of reoperation. Patients with severe deformity in SVA, controlling for levels fused and BL deformity, demonstrated a higher likelihood of any complication in the F and SF by the mFI (OR: 2.1, p=.047) and reoperation by mFI and FI [OR: 3.2; p=.008; OR: 3.8; p=.016, respectively]. Revisions demonstrated higher odds of any complication (OR: 3.3; p=.002), higher likelihood of implant failure (OR: 2.8; p=.03), and a higher chance of developing PJK by one year using mFI [OR: 3.2; p=0.03].

Conclusions: Severe frailty predicted an increased likelihood of infections and reoperations, as compared to the other frailty indices. The mFI-ASD may have superior utility when assessing risks in severely frail patients, particularly in patients with substantial deformity who are undergoing revision surgery.