Complement depletion deteriorates clinical outcomes of severe abdominal sepsis: a conspirator of infection and coagulopathy in crime?

PLoS One. 2012;7(10):e47095. doi: 10.1371/journal.pone.0047095. Epub 2012 Oct 16.


Background: The complement depletion commonly occurred during sepsis, but it was often underestimated compared with severe infection or coagulation dysfunction.

Objective: This study was designed to investigate the alteration of complement system in patients with severe abdominal sepsis and evaluate the role of complement depletion in prognosis of such patients. The relationship between complement depletion and infection or coagulopathy was also explored.

Methods: Forty-five patients with severe abdominal sepsis were prospectively conducted among individuals referral to SICU. Currently recommended treatments, such as early goal-directed resuscitation, source control and antibiotics therapy, were performed. Acute physiology and chronic health evaluation II (APACHE II) and sepsis related organ failure assessment (SOFA) scores were employed to evaluate severity. Plasma levels of C3, C4, CRP, PCT, D-dimer and other parameters were detected within eight times of observation. The 28-day mortality, length of stay, and postoperative complications were compared between complement depletion and non-complement depletion groups.

Results: Within the study period, eight (17.8%) patients died, five of them suffering from complement depletion. The overall incidence of complement depletion was 64.4%. At admission, mean complement C3 and C4 levels were 0.70 and 0.13 mg/mL, respectively. Using ROC analysis for mortality prediction, the area under the curve of C3 was 0.926 (95% CI, 0.845-0.998, P<0.001), with optimal cutpoint value of 0.578 mg/mL. Complement C3 depletion was shown to be no correlation to severity scores, however, strongly correlated with elevated D-dimer, PCT concentrations and increased postoperative complications.

Conclusions: Complement C3 depletion was found to be connected to poor prognosis in severe abdominal sepsis. This depletion seems to be associated with coagulopathy and aggravated infection during sepsis, which should be paid close attention in critical care.

Trial registration: NCT01568853.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Blood Coagulation Disorders / blood
  • Blood Coagulation Disorders / etiology
  • Blood Coagulation*
  • Complement C3 / immunology
  • Complement System Proteins / metabolism*
  • Female
  • Fistula / complications
  • Humans
  • Intraabdominal Infections / complications
  • Male
  • Middle Aged
  • Prognosis
  • Prospective Studies
  • ROC Curve
  • Sepsis / blood*
  • Sepsis / etiology
  • Sepsis / mortality*
  • Severity of Illness Index


  • Complement C3
  • Complement System Proteins

Associated data


Grant support

This study was supported by grants from the Climbing Program in Natural Science Foundation of Jiangsu Province for Distinguished Scholars (No. BK2010017) and the High-Level Personnel Training Project, Jiangsu, China (BRA2011232). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.