Association of early interleukin-6 level with injury severity and mortality in trauma patients: Systematic review and meta-analysis

Abstract

BACKGROUND

Polytrauma is associated with the release of various biomarkers, including interleukin (IL)-6, a proinflammatory cytokine with prognostic value.

AIM

To evaluate the association between IL-6 measured within the first 24 hours of admission and the injury severity score (ISS) among adult polytrauma patients and to explore the link between early IL-6 levels and in-hospital mortality.

METHODS

We conducted a systematic review and meta-analysis of articles published between 2004 and 2024 in the OVID EMBASE and PubMed databases. The primary outcomes of interest were ISS and all-cause in-hospital mortality. Heterogeneity among the included studies was assessed using the I² statistic. Correlations were performed using Pearson’s or Spearman’s correlation coefficients. The Newcastle-Ottawa Scale was used to assess bias in the included studies.

RESULTS

A total of 1126 studies were screened, of which 15 were selected, yielding 2106 polytrauma patients. The pooled effect size for the correlation between IL-6 and ISS using the Pearson’s coefficient was 0.49 [95%CI: 0.36-0.60; I²: 72.2%, P (heterogeneity) = 0.02], while that for studies using the Spearman’s coefficient was 0.50 [95%CI: 0.41-0.58; I²: 33.2%, P (heterogeneity) = 0.18]. Six studies indicated that IL-6 levels were significantly elevated in non-survivors compared with survivors.

CONCLUSION

Among polytrauma patients, elevated IL-6 levels within the first 24 hours of admission are associated with higher rates of severe injury and in-hospital mortality. Future research should investigate how early IL-6 levels can be used with other biomarkers to predict injury severity and worse outcomes. Additionally, larger-scale studies should be conducted to assess the tool's validity across a variety of populations.

Keywords: Serum interleukin-6; Polytrauma; Mortality; Injury severity score; Meta-analysis

Core Tip: Polytrauma is associated with increased morbidity and mortality. Use and identification of biomarkers as prognostic indicators in polytraumatized patients is therefore important. Interleukin (IL)-6 is a proinflammatory cytokine that is often elevated in polytrauma patients and is linked with worse outcomes and more severe injury. However, to date, there is only one meta-analysis published in English literature 7 years ago looking at the association between injury severity and IL-6. By integrating more recent evidence, this meta-analysis provides further support for IL-6 as a prognostic indicator not only for injury severity but also for mortality among adult polytrauma patients.