Background: Older age and female gender are known factors in the development of persisting post concussion symptoms (PCS) following mild head injury (MHI). Very few studies however have examined these variables in permanent PCS.
Objective: This systematic review empirically examines the extent to which such factors pertain to this group.
Methods: Systematic electronic data base searches identified all long-term studies of two types: first, those with correlations between age or gender and outcome; second, those providing the mean ages or gender mixes of samples selected for poor outcome and samples not selected for such.
Results: Twenty studies from 1341 abstracts were ultimately analysed. Correlation studies showed poorer outcome to be associated with both older age (3/4 studies) and female gender (2/4 studies). Those with poor long-term outcome had a significantly higher mean age (40.6) than non- selected patients (32.5). The proportion of men in selected samples (54.8%) was significantly lower than those in non-selected ones (66.5%).
Conclusions: Older age is a strong vulnerability factor in the development of permanent PCS and female gender is a significant one.
Keywords: Mild head injury; permanent post concussion symptoms.