Prognostic Indicators

For ABI rehabilitation, it is important to know which prognostic indicators are significantly related to outcomes. Prognostic indicators can include such variables as injury severity, etiology of injury, age, rehabilitation length of stay, duration of post-traumatic amnesia, etc. The table below summarizes the most common TBI prognostic indicators identified in the literature.

Table: Common Prognostic Indicators for ABI

  • Age
  • Gender
  • Presence of prior brain injury
  • Injury severity
  • Length of coma
  • Initial Glasgow Coma Scale (GCS) score
  • Injury etiology
  • Rehabilitation length of stay
  • Duration of post-traumatic amnesia (PTA)
  • Timing of rehabilitation
  • Intensity of rehabilitation
  • Nature of injury (TBI versus nTBI)
  • Presence of comorbidities


Bushnik et al. (2003) focused on a variety of etiologies, such as MVAs, assaults, and falls. They demonstrated that individuals involved in MVAs initially incurred more severe injuries than individuals injured by assaults, falls, or other causes. However, at one year post-injury individuals with TBI related to MVAs reported the best functional and psychosocial outcomes, while individuals with violence-related TBI reported the highest unemployment rates and lowest Community Integration Questionnaire scores (Bushnik et al. 2003). Individuals with TBI related to falls or ‘other’ etiologies had outcomes that fell somewhere between those injured by MVAs and assaults. This occurred despite the fact there were no functional differences between the groups at discharge from rehabilitation.

Asikainen et al. (1998) focused on the effects of hospital admission Glasgow coma scale (GCS) score, length of coma, and duration of post-traumatic amnesia on outcomes. While hospital admission GCS score positively correlated with functional outcome, as measured by Glasgow Outcome Scale scores, length of coma and duration of post-traumatic amnesia correlated with both functional and occupational outcomes. Poor scores on functional measures (e.g., mobility, eating, or grooming) have also been found to be significant predictors of premature death ( Colantonio et al. 2008). Notably, limitation in eating was one of the most important predictors of mortality (Ratcliff et al. 2005).

The nature of the injury seems to play a predictive role in patient outcomes as well. For instance, Colantonio et al. (2011) reported that the diagnosis of nTBI was associated with a lower Functional Independence Measure rating at admission and at discharge, more comorbidity diagnoses, and longer lengths of stay in inpatient rehabilitation. Significantly more nTBI patients died in acute care, whereas more patients with TBI were discharged home, to inpatient rehabilitation care, or to a long term care facility (Chan et al. 2013c).

The presence of comorbidities may affect patient outcome as well. Having a psychiatric comorbidity increased the odds of having an ALC day among patients with TBI by 73% (Chen et al. 2012). Similarly, increasing Charlson Comorbidity Index category increased the odds of having an ALC day by 9% in the TBI population. A study by Rapoport et al. (2000) demonstrated that major depression in older adults in the first months after TBI had persisting adverse effects on outcome. This finding is particularly problematic since studies have demonstrated that major depression is quite common in the TBI population, and associated with negative prognosis (Rogers & Read 2007).