Frequency and extent of cognitive complaint following adult civilian mild traumatic brain injury: a systematic review and meta-analysis.

Objective: Cognitive symptoms are associated with return to work, healthcare use and quality of life after mild traumatic brain injury (mTBI). Additionally, while overall 'post-concussion' symptoms are often present at similar levels in mTBI and control groups, cognitive complaints may be specifically elevated in mTBI. A systematic review and meta-analysis was conducted to investigate the frequency and extent of cognitive complaints following adult civilian mTBI, and compare it to the frequency and extent of complaints in control populations (PROSPERO: CRD42020151284).

Method: This review included studies published up to March 2022. Thirteen studies were included in the systematic review, and six were included in the meta-analysis. Data extraction and quality assessment were conducted by two independent reviewers.

Results: Cognitive complaints are common after mTBI, although reported rates differed greatly across studies. Results suggested that mTBI groups report cognitive complaints to a significantly greater extent than control groups (Hedges' g = 0.85, 95% CI 0.31-1.40, p = .0102). Heterogeneity between studies was high (τ² = 0.20, 95% CI 0.04-1.58; I² = 75.0%, 95% CI 43.4%-89.0%). Between-group differences in symptom reporting were most often found when healthy rather than injured controls were employed.

Conclusions: Cognitive complaints are consistently reported after mTBI, and are present at greater levels in mTBI patients than in controls. Despite the importance of these complaints, including in regards to return to work, healthcare use and quality of life, there has been limited research in this area, and heterogeneity in research methodology is common.