Abstract
Frailty is a condition characterized by a high vulnerability to low-power stressor. Frailty increases with age and is associated with higher complications and mortality. Several indexes have been used to quantify frailty. Spine diseases, both degenerative and oncologic, frequently require surgery which is related to complications and mortality. Aim of the present systematic review was to collect the most frequently used frailty indexes in clinics to predict surgical outcomes in patients affected by spine diseases, taking into account gender differences. Three databases were employed, and 29 retrospective clinical studies were included in this systematic review. The identified spine pathologies were primary and metastatic spine tumors, adult spine deformity (ASD), degenerative spine disease (DSD), cervical deformity (CD) and other pathologies that affected lumbar spine or multiple spine levels. Eleven indexes were identified: modified Frailty Index (mFI), Adult spinal deformity frailty index (ASD-FI), mFI-5, Metastatic Spinal Tumor Frailty Index (MSTFI), Fried criteria, Cervical deformity frailty index (CD-FI), Spinal tumor frailty index (STFI), Frailty Phenotype criteria (FP), Frailty Index (FI), FRAIL scale and Modified CD-FI (mCD-FI). All these indexes correlated well with minor and major postoperative complications, mortality and length of stay in hospital. Results on gender differences and frailty are still conflicting, although few studies show that women are more likely to develop frailty and more complications in the post-operative period than men. This systematic review could help the surgeon in the adoption of frailty indexes, before the operation, and in preventing complications in frail patients.