Using IL-6 Concentrations in the First 24 h Following Trauma to Predict Immunological Complications and Mortality in Trauma Patients: a Meta-analysis

Purpose: In previous studies, interleukin-6 (IL-6) has been shown to have a high predictive value for the development of complications and mortality after trauma; however, there is some uncertainty around these results. The aim of this meta-analysis was to assess the value of early IL-6 levels (within the first 24 h after trauma) for predicting post-traumatic complications [acute respiratory distress syndrome (ARDS), systemic inflammatory response syndrome (SIRS), sepsis, multiple organ failure (MOF), and multiple organ dysfunction syndrome (MODS)] and mortality.

Methods: A systemic literature review (from January 01, 1990, to June 03, 2017) of English-language articles was carried out using Pubmed, the Cochrane Central Register of Controlled Trials, Embase, and Web of Science. The search terms used were IL-6 (IL6, IL-6, interleukin 6, or interleukin-6); trauma (trauma*, polytrauma*, multitrauma*, injury, or injury severity score); complications (complication*, ARDS, SIRS, sepsis, MOF, or MODS); and mortality (survival, death). Eleven publications (775 patients) out of 1812 fulfilled the criteria. Fixed-effective models were used for data analysis. Statistical heterogeneity was estimated by a Chi-squared Q test and I statistics, and publication bias was assessed with Egger's test.

Results: Results showed that the concentrations of IL-6 within the first 24 h after trauma were significantly higher in the group of patients who had complications or who died [standardized mean difference (SMD) = 0.399; 95% confidence interval (CI) 0.217, 0.580; I  = 0.0%; P(heterogeneity) = 0.489]. Subgroup results showed a significant correlation for mortality [SMD = 0.610; 95% CI 0.322, 0.898; I  = 0.0%; P(heterogeneity) = 0.708] and MOF/MODS [SMD = 0.334; 95% CI 0.028, 0.639; I  = 0.0%; P(heterogeneity) = 0.512] with IL-6, but not for sepsis [SMD = 0.194; 95% CI - 0.095, 0.484; I  = 0.0%; P(heterogeneity) = 0.512]. Significance was also found in both ISS ≥ 9 [SMD = 0.461, 95% CI 0.131, 0.791, I  = 5.6%, P(heterogeneity) = 0.365] and ISS ≥ 16 [SMD = 0.372, 95% CI 0.155, 0.588, I  = 1.5%, P(heterogeneity) = 0.413].

Conclusion: In conclusion, this meta-analysis showed that serum concentration of IL-6 within the first 24 h after trauma could be useful for the prediction of post-traumatic complications, particularly MOF/MODS and mortality.