Hypotension and Adverse Outcomes in Moderate to Severe Traumatic Brain Injury: A Systematic Review and Meta-Analysis

Abstract

Importance: Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. Hypotension in patients with TBI is associated with poorer outcomes. A comprehensive review examining adverse outcomes of hypotension in patients with TBI is needed.

Objective: To investigate the mortality and incidence of hypotension in patients with TBI.

Data sources: A search of studies published before April 2024 was conducted using MEDLINE, MEDLINE In Process, ePubs, Embase, Classic+Embase, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews for primary research articles in English, including randomized control trials, quasirandomized studies, prospective cohorts, retrospective studies, longitudinal studies, and cross-sectional surveys.

Study selection: Inclusion criteria were patients aged at least 10 years with moderate to severe TBI with hypotension. The exclusion criteria were mild TBI (due to the differences in management principles from moderate to severe TBI). Data were screened using Covidence software with multiple reviewers.

Data extraction and synthesis: This meta-analysis conforms to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) and Meta-analysis of Observational Studies in Epidemiology (MOOSE) reporting guidelines for assessing data quality and validity. Primary outcomes (unadjusted and adjusted odds ratios [ORs]) were calculated using a random-effect model with 95% CIs. Incidence of hypotension was derived using logit transformation.

Main outcomes and measures: Main outcomes were association of hypotension with death and/or vegetative state within 6 months and incidence of hypotension. Vegetative state was not reported due to lack of data from included studies. Hypothesis testing occurred before data collection.

Results: The search strategy identified 17 676 unique articles. The final review included 51 studies (384 329 patients). Pooled analysis of found a significant increase in mortality in patients with hypotension and moderate to severe TBI (crude OR, 3.82; 95% CI, 3.04-4.81; P < .001; I2 = 96.98%; adjusted OR, 2.22; 95% CI, 1.96-2.51; P < .001; I2 = 92.21%). The overall hypotension incidence was 18% (95% CI, 12%-26%) (P < .001; I2 = 99.84%).

Conclusions and relevance: This meta-analysis of nearly 400 000 patients with TBI found a significant association of greater than 2-fold odds of mortality in patients with hypotension and TBI. This comprehensive analysis can guide future management recommendations, specifically with respect to blood pressure threshold management to reduce deaths when treating patients with TBI.

Figure 1.. Study Selection Flowchart

CDSR indicates Cochrane Database of Systematic Reviews.

Figure 2.. Association of Hypotension With Vegetative State or Mortality in Patients With Moderate to Severe Traumatic Brain Injury

Dashed black line indicates the summary measure; dotted gray line, line of no effect; diamond, overall pooled effect estimate of adjusted odds ratio (OR), restricted maximum likelihood random-effect model; sizes of squares, study weight. Substudies from Fuller et al were divided based on hypotension thresholds of 70 mm Hg (subgroup a), 80 mm Hg (subgroup b), 90 mm Hg (subgroup c), 100 mm Hg (subgroup d), and 110 mm Hg (subgroup e). Substudies from Huang et al were divided based on moderate traumatic brain injury (subgroup a) and severe traumatic brain injury (subgroup b). Substudies from Newgard et al were divided based on SBP ranges of less than 90 mm Hg (subgroup a), 90 to 105 mm Hg (subgroup b), and 105 to 120 mm Hg (subgroup c). Substudies from Rice et al include different blood pressure measurement settings emergency medical services (subgroup a), emergency department (subgroup b), and emergency medical services and emergency department (subgroup c). Substudies from 2 studies by Shibahashi et al^, were based on thresholds of less than 110 mm Hg (subgroup a), 100 to 109 mm Hg (subgroup b), 90 to 99 mm Hg (subgroup c), 80 to 89 mm Hg (subgroup d), 70 to 79 mm Hg (subgroup e), less than 70 mm Hg (subgroup f). Substudies from Spaite et al include blood pressure thresholds increments of 5 mm Hg from less than 60 mm Hg (subgroup a) to less than 120 mm Hg (subgroup m).

Figure 3.. Incidence of Hypotension in Patients With Moderate to Severe Traumatic Brain Injury

Dashed line indicates the summary measure; diamond, overall pooled effect estimate of incidence, restricted maximum likelihood random-effect model; squares, individual estimates; sizes of squares, study weight. Substudies from Kim et al were divided based on blood pressure thresholds at less than 90 mm Hg (subgroup a) and less than 110 mm Hg (subgroup b).

Figure 4.. Association of Hypotension With Vegetative State or Mortality in Patients With Moderate to Severe Traumatic Brain Injury Based on Subgroups

Dashed black line indicates the summary measure; dotted line, line of no effect; diamond, overall pooled effect estimate of adjusted odds ratio (OR), restricted maximum likelihood random-effect model. AIS indicates Abbreviated Injury Scale; BP, blood pressure; ED, emergency department; EMS, emergency medical services; GCS, Glasgow Coma Scale; ICU, intensive care unit.