Objective: To identify the systems available to sub-classify mild traumatic brain injury (TBI) and to determine their utility in predicting 1-year outcome.
Methods: A systematic review to identify mild-TBI sub-classification systems was conducted until March 2016. The identified systems were applied to a cohort of N = 290 adults who had experienced a mild-TBI, and who had been assessed for post-concussion symptoms 1-year post injury. ANOVAs and regression models were used to determine whether each sub-classification system could distinguish between outcomes and to explore their contribution to explaining variance in post-concussion symptoms 1-year post injury.
Results: Nineteen sub-classification systems for mild-TBI met the inclusion criteria for this review. The Saal (1991) classification system significantly differentiated the experience of post-concussion symptoms in our cohort 1-year post injury (F = 2.39, p = 0.05). However, the findings did not remain significant following correction for multiple comparisons and inclusion of socio-demographic and contextual factors in the regression model.
Conclusions: Current sub-classification systems fail to explain much of the variance in post-concussion symptoms 1 year following mild-TBI. Further research is needed to identify the factors (including socio-demographic and contextual factors) to determine, who may be at risk of developing persistent post-concussion symptoms.