Identification of Clinically Significant Cytokine Signature Clusters in Patients With Septic Shock

OBJECTIVES: To identify cytokine signature clusters in patients with septic shock. DESIGN: Prospective observational cohort study. SETTING: Single academic center in the United States. PATIENTS: Adult (≥ 18 yr old) patients admitted to the medical ICU with septic shock requiring vasoactive medication support. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: One hundred fourteen patients with septic shock completed cytokine measurement at time of enrollment (t₁) and 24 hours later (t₂). Unsupervised random forest analysis of the change in cytokines over time, defined as delta (t₂-t₁), identified three clusters with distinct cytokine profiles. Patients in cluster 1 had the lowest initial levels of circulating cytokines that decreased over time. Patients in cluster 2 and cluster 3 had higher initial levels that decreased over time in cluster 2 and increased in cluster 3. Patients in clusters 2 and 3 had higher mortality compared with cluster 1 (clusters 1-3: 11% vs 31%; odds ratio [OR], 3.56 [1.10-14.23] vs 54% OR, 9.23 [2.89-37.22]). Cluster 3 was independently associated with in-hospital mortality (hazard ratio, 5.24; p = 0.005) in multivariable analysis. There were no significant differences in initial clinical severity scoring or steroid use between the clusters. Analysis of either t₁or t₂cytokine measurements alone or in combination did not reveal clusters with clear clinical significance. CONCLUSIONS: Longitudinal measurement of cytokine profiles at initiation of vasoactive medications and 24 hours later revealed three distinct cytokine signature clusters that correlated with clinical outcomes.