Keeping Score on SIRS

Sepsis and systemic inflammatory response syndrome (SIRS) occur at a rate of 1.5% to 8% per year in the United States. These conditions are the subject of current research in veterinary medicine because not much is known in canine and feline populations about prognostic indicators, accurate diagnosis, and treatment. Early recognition of sepsis and SIRS in both human and veterinary medicine is necessary to initiate effective treatment for these critically ill patients. C-reactive protein (CRP) is an inflammatory marker produced mainly by the liver as part of an acute-phase response after stimulation of hepatocytes by proinflammatory cytokines (interleukin-6, interleukin-1, and tumor necrosis factor-alpha). Acute-phase proteins indicate the presence of infectious or inflammatory processes, but they do not predict the underlying cause. Human CRP has a short half-life of approximately 7 hours; it has been used as a sepsis marker and as a marker to determine duration of antibiotic treatment in neonatal septicemia in children. In dogs, CRP is elevated in certain disorders, and the increase is correlated with the severity of the disease. This study evaluated the concentrations of CRP in dogs with nonseptic SIRS and those with sepsis. The authors also attempted to correlate the survival rate and the CRP concentration.

Dogs were included in the study if they met previously described criteria for SIRS: increase or decrease in body temperature, tachycardia or tachypnea, leukopenia or leukocytosis, and the presence of immature neutrophils. Cultures of various body cavities as related to the individual dog’s disease were performed. Sixty-one dogs were included in the study; 48 were determined to be septic and 13 were nonseptic. A higher incidence of infections caused by a single gram-negative bacteria (versus gram-positive) was seen. Of 19 aerobic and anaerobic cultures performed, 8 were anaerobic. CRP values were significantly higher than in the control group on days 0 and 1. Serum CRP concentrations on days 0, 1, and 2 did not differ between dogs with nonseptic SIRS and dogs with sepsis. Survival was correctly predicted in 29 of 31 (94%) dogs, but death was correctly predicted in only 3 of 10 (30%) dogs. Therefore, the prediction accuracy was 88% overall—in other words, the false-positive rate was 22%. The authors did show a correlation between decreasing CRP concentrations and recovery from disease.

COMMENTARY: The mortality rate of sepsis in dogs is high: 50% to 67%. A scoring system that could correlate poor patient outcome from the beginning of treatment on the basis of CRP concentrations would be useful, but unfortunately the data that support the use of CRP as any indicator for treatment or prognosis do not yet exist. More studies carefully investigating CRP and canine disease are necessary. Perhaps studying the presence of CRPs in inflammatory effusions, or correlating CRPs with certain biochemical changes during the course of disease, would be useful.

Use of C-reactive protein to predict outcome in dogs with systemic inflammatory response syndrome or sepsis. Gebhardt C, Hirschberger J, Rau S, et al. J VET EMERG CRIT CARE 19:450-458, 2009.