Systematic review of the prognosis after mild traumatic brain injury in adults: cognitive, psychiatric, and mortality outcomes: results of the International Collaboration on Mild Traumatic Brain Injury Prognosis.

Objective: To synthesize the best available evidence on objective outcomes after adult mild traumatic brain injury (MTBI).

Data Sources: MEDLINE and other databases were searched (2001-2012) for studies related to MTBI. Inclusion criteria included published, peer-reviewed articles in English and other languages. References were also identified from the bibliographies of eligible articles.

Study Selection: Randomized controlled trials and cohort and case-control studies were selected according to predefined criteria. Studies had to have a minimum of 30 MTBI cases and assess objective outcomes in adults.

Data Extraction: Eligible studies were critically appraised using a modification of the Scottish Intercollegiate Guidelines Network (SIGN) criteria. Two reviewers independently reviewed each study and extracted data from accepted articles into evidence tables.

Data Synthesis: Evidence was synthesized qualitatively according to modified SIGN criteria, and studies were categorized as exploratory or confirmatory based on the strength of their design and evidence. After 77,914 records were screened, 299 were found to be relevant and critically reviewed, and 101 were deemed scientifically admissible. Of these, 21 studies that were related to the objective outcomes form the basis of this review. Most evidence indicates the presence of cognitive deficits in the first 2 weeks post-MTBI, and some evidence suggests that complete recovery may take 6 months or a year. A small number of studies indicate that MTBI increases the risk of psychiatric illnesses and suicide.

Conclusions: Early cognitive deficits are common, and complete recovery may be prolonged. Conclusions about mortality post-MTBI are limited. This review has implications for expected recovery after MTBI and MTBI-related health sequelae. Well-designed confirmatory studies are needed to understand the medium- to long-term consequences of MTBI and to further evaluate the effect of prior MTBI and injury severity on recovery.