The Impact of a Prior Traumatic Brain Injury and Injury Characteristics on Frailty in the Canadian Longitudinal Study on Aging

OBJECTIVE: Using the Canadian Longitudinal Study on Aging (CLSA), we tested the hypothesis that those with a TBI would have increased frailty compared with those without, and we also tested our secondary hypothesis that spending more time unconscious and/or requiring hospitalization following injury is associated with increased frailty. DESIGN: This observational, community-based cohort study uses data from the CLSA (comprehensive cohort). SETTING: Not applicable. PARTICIPANTS: Middle- and older-aged adults at baseline (non-TBI=20,173 [63±10y, 54% female], TBI=6499 [61±9y, 40% female]) and 3-year follow-up were included. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Frailty was measured with a 43-item frailty index (derived from the 65-item CLSA frailty index) and determined as a ratio of deficit present to deficits measured. Participants self-reported TBI outcome information (eg, cause, time unconsciousness, and treatment). Covariate-adjusted linear regressions were conducted by cause of TBI to assess changes in frailty among individuals with a TBI. Time unconscious and treatment were analyzed separately within each cause-of-injury group, compared against those with a TBI who did not fall within the group of interest. RESULTS: Frailty was higher among the TBI group at baseline (means±SD:0.10±0.06) and 3-year follow-up (0.12±0.07) compared with the non-TBI group at baseline (0.09±0.06) and 3-year follow-up (0.11±0.07; all P<.001). Those with a TBI demonstrated larger increases in frailty from baseline to 3-year follow-up compared with those who did not have a TBI (β=-0.33; P<.001). There were no differences in frailty changes between TBI cause groups (ie, vehicle, fall, and sport), and no differences in frailty changes among these groups when stratified by time unconsciousness or treatment method. CONCLUSION: Having a TBI is indicative of worsened frailty changes over a 3-year follow-up, regardless of the cause, time spent unconscious, or treatment method.