Longstanding symptoms after mild traumatic brain injury (MTBI) may be attributable to factors other than the MTBI, pretraumatic as well as posttraumatic factors. A recognised problem when assessing pretraumatic factors is underestimation due to recall bias. The aim of the study was to explore prognostic factors for the development of postconcussional disorder (PCD) after MTBI.

In a prospective cohort of MTBI patients, pretraumatic (previous psychiatric disorder, personality traits, coping ability, GAF, psychosocial stressors, medical condition), peritraumatic (duration of loss of consciousness and amnesia, GCS score at presentation, intracranial hemmorhage) and posttraumatic (posttraumatic stress, anxiety, depression) factors were thoroughly assessed within one week after the trauma, when recall bias was estimated to be negliable. Outcome (persisting symptoms and disability) was assessed at three months post injury. Logistic regression analysis was performed to calculate the independent contribution to the outcome from different factors.

Three months post injury, 17 % had postconcussional disorder (PCD). Posttraumatic hyperarousal (OR 9.08), concurrent medical conditions (OR 6.19), female gender (OR 5.54) and psychosocial stressors (OR 11.93) independently predicted PCD, but injury related factors had no significant relation to the outcome.

Pre- and posttraumatic factors significantly contribute to the long term outcome after MTBI and should be taken into account in the clinical assessment of patients with PCD. The findings support an etiological model that recognises predisposing and perpetuating factors as well as the precipitating head injury as determinants for the development of PCD.