ObjectiveTo examine whether changes in interleukin (IL)-6 and IL-10 concentrations in patients with systemic inflammatory response syndrome (SIRS) can predict a poor outcome.DesignProspective study.SettingEmergency and intensive care unit of a medical school hospital.PatientsTwenty-five patients who fulfilled the criteria for SIRS.InterventionsBlood samples were collected for cytokine determinations.Measurements and Main ResultsIL-6 and IL-10 concentrations were measured by enzyme-linked immunosorbent assay in plasma samples. Blood samples were obtained at 0, 1, 2, and 4 days from patients who fulfilled the criteria for SIRS. Of 25 patients, 19 survived and the other six patients died of multiple organ failure. Although IL-6 and IL-10 concentrations in survivors decreased gradually from 186.1 +/- 34.4 to 93.6 +/- 18.9 (SEM) pg/mL (p < .05) and from 77.4 +/- 21.2 to 32.0 +/- 11.8 pg/mL (p < .05), IL-6 concentrations in nonsurvivors did not. Although the ratio of IL-6 to IL-10 in survivors was almost stable, the ratio in nonsurvivors increased from 5.5 +/- 3.1 to 18.7 +/- 2.8 (p < .05). Multivariate analysis showed that when heart rate, mean arterial pressure, IL-6, IL-10, and the ratio of IL-6 to IL-10 were taken into account, there only remained a relationship between the ratio of IL-6 to IL-10 and outcome.ConclusionsIn nonsurvivors, IL-6 concentrations did not decrease, IL-10 concentration decreased, and the ratio of IL-6 to IL-10 increased. An increase in the ratio of IL-6 to IL-10 indicated a correlation with a poor outcome. (Crit Care Med 1999; 27:1262-1264)