The relationship Between Time to Command-Following and Outcomes after Traumatic Brain Injury: The “1%” Rule

Introduction: The ability for command-following is used by acute care clinicians to establish overall prognosis after traumatic brain injury (TBI). The accuracy of prognoses based on command-following at different post-injury timepoints is unknown. The objective is to evaluate the association between absence of command-following and outcomes 1-year after TBI.

Methods: Participants enrolled in the TBI Model Systems (TBI-MS) who were followed 1-year post injury, with validation in the Brain Trauma Research Center (BTRC). TBI-MS is a US-based multi-center study of patients with moderate-severe TBI, and the BTRC consists of participants with severe TBI admitted to a single US level 1 trauma center. The number of days between acute admission and first documentation of command-following) and Glasgow Outcome Scale Extended (GOSE) score at 1-year post TBI were evaluated.

Results: TBI-MS: N=9,052 (mean ± SD age 38 ± 18 years, 76% male, 67% white); BTRC: N=228 (mean age 37 ± 17 years, 76% male, 91% white). TBI-MS patients were more likely than those in BTRC to follow commands during acute hospitalization (90% vs 63%; p< 0.001) and had a shorter median time to command-following (5 vs 9.5 days; p< 0.001). For each additional week without command-following, the odds ratio for death or dependency at 1 year was 1.30 (95% CI: [1.26,1.35]; p< 0.001) in TBI-MS and 1.49 ([1.15, 1.97]; p=0.003) in BTRC. Time to command-following had an AUC of 0.61 [0.59, 0.63] in TBI-MS and 0.65 [0.53, 0.76]) in BTRC. Each additional inpatient day without command-following was associated with 1.18% (1.16%, 1.20%) increase in the proportion of participants with death or dependency at 1 year outcome in TBI-MS and 1.05% (0.99%, 1.11%) in BTRC.

Conclusion : After moderate to severe TBI, there is a small increase in the odds of death or dependency for each additional week without command-following. We observed in both rehab-enrolled and acute-care enrolled cohorts a consistent ~1% increase in the likelihood of death or dependency with each additional day without command-following.