Traumatic brain injury is a major cause of death and disability, yet many predictors of outcome are not precise enough to guide initial clinical decision-making. Although increasingly used in the early phase following traumatic brain injury, the prognostic utility of MRI remains uncertain. We thus undertook a systematic review and meta-analysis of studies evaluating the predictive value of acute MRI lesion patterns for discriminating clinical outcome in traumatic brain injury.
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Studies of adults who had MRI in the acute phase following moderate or severe traumatic brain injury. Our primary outcomes were all-cause mortality and the Glasgow Outcome Scale.
Two authors independently performed study selection and data extraction. We calculated pooled effect estimates with a random effects model, evaluated the risk of bias using a modified version of Quality in Prognostic Studies and determined the strength of evidence with the Grading of Recommendations, Assessment, Development, and Evaluation.
We included 58 eligible studies, of which 27 (n = 1,652) contributed data to meta-analysis. Brainstem lesions were associated with all-cause mortality (risk ratio, 1.78; 95% CI, 1.01–3.15; I2 = 43%) and unfavorable Glasgow Outcome Scale (risk ratio, 2.49; 95% CI, 1.72–3.58; I2 = 81%) at greater than or equal to 6 months. Diffuse axonal injury patterns were associated with an increased risk of unfavorable Glasgow Outcome Scale (risk ratio, 2.46; 95% CI, 1.06–5.69; I2 = 74%). MRI scores based on lesion depth demonstrated increasing risk of unfavorable neurologic outcome as more caudal structures were affected. Most studies were at high risk of methodological bias.
MRI following traumatic brain injury yields important prognostic information, with several lesion patterns significantly associated with long-term survival and neurologic outcome. Given the high risk of bias in the current body of literature, large well-controlled studies are necessary to better quantify the prognostic role of early MRI in moderate and severe traumatic brain injury.
1CHU de Québec – Université Laval Research Centre, Population Health and Optimal Health Practices Research Unit (Trauma-Emergency-Critical Care Medicine), Université Laval, Québec, QC, Canada.
2Department of Medicine, University of Toronto, Toronto, ON, Canada.
3Department of Medicine, Université Laval, Québec, QC, Canada.
4Department of Anesthesiology and Critical Care Medicine, Division of Critical Care Medicine, Université Laval, Québec, QC, Canada.
5Department of Social and Preventive Medicine, Université Laval, Québec, QC, Canada.
6George and Fay Yee Centre for Healthcare Innovation, Knowledge Synthesis, Winnipeg, MB, Canada
7CancerCare Manitoba, Department of Haematology and Medical Oncology, University of Manitoba, Winnipeg, MB, Canada.
8Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada.
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Dr. Boutin is a recipient of a Doctoral Award (Frederick Banting and Charles Best Canada Graduate Scholarships) from the Canadian Institutes of Health Research (CIHR). Drs. Lauzier and Moore are recipients of a Clinician Scientist Award from the Fonds de Recherche du Québec - Santé. Drs. Moore, Zarychanski, and Turgeon are/were recipients of a New Investigator Award from the CIHR. Dr. Turgeon’s institution received funding from the CIHR Foundation Scheme Grant, and he is the Canada Research Chair in Critical Care Neurology and Trauma. The remaining authors have disclosed that they do not have any potential conflicts of interest.
Systematic review registration: PROSPERO CRD42015017074.
Drs. Haghbayan, Lauzier, Moore, Zarychanski, Boutin, Fergusson, and Turgeon have made substantial contributions to the conception and design of the study. Drs. Haghbayan, Boutin, Laflamme, Shemilt, Douville, and Turgeon have been involved in the data acquisition, data analysis, and the drafting of the article. All authors have been involved in revising the article critically for important intellectual content. All the authors have given final approval of the version to be published and agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of the work are resolved.
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