Not All Frailty is Equivalent: Comparing Frailty Index Scales in Their Capacity to Predict Mortality in Older Adults with Traumatic Brain Injuries

Introduction: Over 30% of older adults experiencing mild-moderate traumatic brain injuries (TBIs) die within one-year of injury. While frailty scores predict poor outcomes in all-age TBI patients, we lack clarity in which scale is best suited for the high-risk older adult population. The primary objective of this study was to compare three frailty indices for their capacity to predict one-year mortality.

Methods: This retrospective study included patients presenting to a Level I trauma center with isolated mild-moderate TBIs between 2013-2018. Injury characteristics, patient demographics, and frailty variables were obtained from electronic medical records. Date of death was obtained through public records. Differences were considered significant if p≤0.05 with univariable analysis.

Results: Of the 977 older adults with mild-moderate TBIs, 365 (37.4%) died after hospital discharge, and within one-year of index trauma. There was a significant age difference between those who survived (80.43±0.52) and died (84.69±0.74) at one-year (p < 0.001). The two groups demonstrated no difference in Glasgow Coma Scale scores (p=0.128). When comparing frailty index scales, there were significant differences between the survival and deceased groups when using Risk Analysis Index (RAI; 16.73±0.535 versus 20.59±0.813; p< 0.001) and Modified Frailty Index-11 (mFi-11; 0.248±0.013 versus 0.289±0.016; p=0.022), but not the Collaborative European Neurotrauma Effectiveness Research in Traumatic Brain Injury frailty index (CENTER-TBI frailty index; 0.293±0.010 versus 0.314±0.013; p=0.125).

Conclusion : In older adults with mild-moderate TBIs, the RAI and mFi-11 frailty scores, but not the CENTER-TBI frailty index, differ when comparing patients that survive and die at one-year. Further work is needed to understand how frailty scores may guide interventions to mitigate mortality in this high-risk population.