Meta-analysis of plasma to red blood cell ratios and mortality in massive blood transfusions for trauma

Abstract

Background

The current military paradigm for blood transfusion in major trauma favours high plasma:RBC ratios. This study aimed determine whether high plasma:red blood cell (RBC) ratios during massive transfusion for trauma decrease mortality, using meta-analysis of contemporaneous groups matched for injury severity score.

Methods

A systemic review of the published literature for massive blood transfusions in trauma was performed. Patients were categorised into groups based on plasma:RBC transfusion ratios. Meta-analysis was only performed when there were no significant differences in Injury Severity Score (ISS) between ratio groups within studies. The main endpoint was 30-day mortality.

Results

Six observational studies reporting outcomes for 1885 patients were included in this meta-analysis. Five studies were from civilian environments and one from a military setting. Ratio cut-offs at 1:2 were the most commonly reported, demonstrating a survival advantage with higher ratios (OR 0.49, 95% CI 0.31–0.80, p=0.004). Ratios≥1:2 showed a significant reduction in mortality compared to lower ratios (OR 0.56, 95% CI 0.40–0.78, p<0.001). Reducing the cut-off level was still protective (ratios between 1:2.5 and 1:4, OR 0.41), although the confidence interval was wide (0.16–1.00, p=0.05) and data heterogenous (I²=78%). Ratios of 1:1 were not proven to confer additional benefit beyond ratios of 1:2 (OR 0.50, 95% CI 0.37–0.68, p<0.001).

Conclusions

In groups matched for ISS, there was a survival benefit with high plasma:RBC resuscitation ratios. No additional benefits of 1:1 over 1:2 ratios were identified.