A systematic review of age and gender factors in prolonged post-concussion symptoms after mild head injury

BACKGROUND: Older age and female gender are known factors in the development of persisting post-concussion symptoms (PCS) after mild head injury (MHI), i.e. at 3+ months. Very few studies have examined longer-term symptoms. A recent review, however, established the importance of these variables in permanent PCS (18+ months). The current study repeats the review for prolonged symptoms (12-18 months). METHODS: Systematic electronic database searches were conducted to identify all studies with data on (i) correlations between age/gender and prolonged outcome and (ii) mean ages/gender mixes of (a) prolonged samples selected for poor symptomatic outcome, (b) prolonged samples not selected for poor outcome and (c) epidemiological studies of MHI patients presenting to hospital. RESULTS: Correlation studies showed poorer outcome to be associated with both older age (2/5 studies) and female gender (5/6 studies). Those with poor prolonged outcome had a significantly higher mean age (35.9) than MHI patients in general (29.9). The proportion of men in these samples (48.6%) was significantly lower than MHI patients in general (66.7%). CONCLUSIONS: Older age and female gender are vulnerability factors in the development of prolonged PCS. The main clinical implications are for how early intervention and reassurance are best provided.