There are limited data regarding serum activin‐A as a biomarker for sepsis. We examined whether serum activin‐A concentration could predict sepsis severity and prognosis in the management of critically ill patients with sepsis.

The subjects were adult patients suspected of having sepsis and admitted to intensive care unit (ICU) from January 2013 to March 2014. Serum activin‐A concentration was measured in blood sampled within 48 h after ICU admission. The primary and secondary outcomes were the diagnostic value of serum activin‐A concentration as a biomarker of sepsis and the prognostic value for predicting the clinical outcomes of sepsis, respectively.

One hundred and thirty patients who had clinically suspected sepsis were included. Most (66.2%) were male; their median age was 65 years, and their Acute Physiology and Chronic Health Evaluation II score was 22.3. Serum activin‐A concentration tended to increase with sepsis severity and differed significantly between those with non‐sepsis and severe sepsis and between those with severe sepsis and septic shock. The risks of sepsis, severe sepsis and septic shock were significantly higher in patients with a serum activin‐A concentration of 251, 319 and 432 pg/mL or greater, respectively. Serum activin‐A concentration was significantly associated with the Acute Physiology and Chronic Health Evaluation II score, Sequential Organ Failure Assessment score, Charlson comorbidity index and ICU mortality.

Serum activin‐A was a predictor of sepsis severity and a prognostic marker in critically ill patients with sepsis. Serum activin‐A concentration in the early phase of sepsis was associated with prognostic indexes on ICU admission and with ICU mortality.