Interleukin 6 is a prognostic indicator of outcome in severe intra-abdominal sepsis

Levels of plasma cytokines and circulating endotoxin were assessed in 41 patients with severe intra-abdominal sepsis. Comparison was made with the Acute Physiology And Chronic Health Evaluation (APACHE) II scoring system. Blood samples were taken within 24 h of onset of the sepsis syndrome and at serial times thereafter. Increased levels of interleukin (IL) 6 (range 50-25,500 pg/ml) were detectable in all patients with sepsis. Eighteen of the 19 deaths were attributable to sepsis and higher levels of IL-6 at the onset of the sepsis syndrome correlated with a poor outcome. The sensitivity of IL-6 concentration in predicting mortality was 86.4 per cent with a specificity of 78.9 per cent and an overall correct classification rate of 82.9 per cent. IL-6 level was a better predictor than APACHE II score (sensitivity 72.7 per cent, specificity 57.9 per cent, correct classification rate 65.9 per cent). Levels of tumour necrosis factor alpha, IL-1 beta and endotoxin did not correlate with mortality rate. Plasma IL-6 concentrations may help in planning future strategies to decrease the mortality rate associated with sepsis.