Blood Interleukin-6 Levels Predict Multiple Organ Dysfunction in Critically Ill Patients

BACKGROUND: Predicting multiple organ dysfunction (MOD) in the late phase of critical illnesses is essential. Cytokines are considered biomarkers that can predict clinical outcomes; however, their predictive value for late-phase MOD is unknown. This study aimed to identify the biomarker with the highest predictive value for late-phase MOD. METHODS: This observational study prospectively evaluated data on adult patients with systemic inflammatory response syndrome, those who presented to the emergency department or were admitted to intensive care units in five tertiary hospitals (n = 174). Seven blood biomarkers levels (interleukin-6 [IL-6], IL-8, IL-10, tumor-necrosis factor-α, white blood cells, C-reactive protein, and procalcitonin) were measured at three timepoints (days 0, 1, and 2). The area under the receiver operating characteristic curve (AUC) was analyzed to evaluate predictive values for MOD (primary outcome, MOD on day 7 [late-phase]; secondary outcome, MOD on day 3 [early-phase]). RESULTS: Of the measured 7 biomarkers, blood IL-6 levels on day 2 had the highest predictive value for MOD on day 7 using single timepoint data (AUC 0.825, 95% confidence interval [CI] 0.754-0.879). Using three timepoint biomarkers, blood IL-6 levels had the highest predictive value of MOD on day 7 (AUC 0.838, 95% CI 0.768-0.890). Blood IL-6 levels using three timepoint biomarkers had also the highest predictive value for MOD on day 3 (AUC 0.836, 95% CI 0.766-0.888). CONCLUSION: Of the measured biomarkers, blood IL-6 levels had the highest predictive value for MOD on days 3 and 7. Blood IL-6 levels predict early- and late-phase MOD in critically ill patients.