Comparison of Frailty Indices and the Charlson Comorbidity Index in Traumatic Brain Injury

Background: Comorbidity scales for outcome prediction in traumatic brain injury (TBI) include the 5-component modified Frailty Index (mFI-5), the 11-component modified Frailty Index (mFI-11), and the Charlson Comorbidity Index (CCI). Objective: To compare the accuracy in predicting clinical outcomes in TBI of mFI-5, mFI-11, and CCI. Methods: The National Trauma Data Bank (NTDB) of the American College of Surgeons (ACS) was utilized to study patients with isolated TBI for the years of 2017 and 2018. After controlling for age and injury severity, individual multivariable logistic regressions were conducted with each of the 3 scales (mFI-5, mFI-11, and CCI) against predefined outcomes, including any complication, home discharge, facility discharge, and mortality. Results: All 3 scales demonstrated adequate internal consistency throughout their individual components (0.63 for mFI-5, 0.60 for CCI, and 0.56 for mFI-11). Almost all studied complications were significantly more likely in frail patients. mFI-5 and mFI-11 had similar areas under the curve (AUC) for all outcomes, while CCI had lower AUCs (0.62-0.61-0.53 for any complication, 0.72-0.72-0.52 for home discharge, 0.78-0.78-0.53 for facility discharge, and 0.71-0.70-0.52 for mortality, respectively). Conclusion: mFI-5 and mFI-11 demonstrated similar accuracy in predicting any complication, home discharge, facility discharge, and mortality in TBI patients across the NTDB. In addition, CCI's performance was poor for the aforementioned metrics. Since mFI-5 is simpler, yet as accurate as the 2 other scales, it may be the most practical both for clinical practice and for future studies with the NTDB.