Systemic inflammatory response syndrome (SIRS) without systemic inflammation

Background

Criteria of SIRS, developed to detect early systemic inflammation (SI), are sensitive enough to include also patients (pts) without SI. To address this problem, we developed composite systemic inflammation score (CSIS) based on phagocyte activation markers to evaluate degree of SI in acutely ill pts with SIRs.

Patients and methods

100 pts at medical emergency were included. CD11b expression levels on neutrophils (PMNs) and monocytes (MO) were determined by flow cytometry, serum levels of IL-6, IL-1β, and TNF-α by ELISA, and of C-reactive protein (CRP) by immunoturbidimetry. To calculate CSIS, IL-6, IL-1β, TNF-α, CRP and CD1 expression levels were each scored 0 to 4 points; maximum CSIS is 20 points.

Results

61 pts had SIRS2, 14 SIRS3, 2SIRS4, 20 sepsis, 2 severe sepsis, and 1 septic shock. Drug intoxication (17 pts) and acute myocardial infarction (15 pts) were most common diagnoses. CD11b expression increased in order : SIRS2 = SIRS3 < Sepsis; CRP in order: SIRS2 < SIRS3 < Sepsis, and IL-6 and IL-1β both in order: SIRS2 < SIRS3 < Sepsis. 13.8% of pts had CSIS 0 indicating virtually absence of SI. CSIS of SIRS2 pts (median 1.5; range 0–8) was lower than that of SIRS3 pts (3.5; 0–9, P = 0.013) and that of Sepsis pts (5; 3–10, P < 0.001); also SIRS3 differed from Sepsis (P = 0.0018). Among 81 pts with CSIS ≥ 1, proportions of pts with increased IL-6, CRP, CD11b, IL-1β, and TNF-α were 79.0%, 72.8%, 61.7%, 25.9% and 2.5%, respectively.

Conclusions

Quantifying phagocyte CD11b expression and circulating IL-6 and CRP concurrently provides a means to identify patient who meets SIRS criteria but lacks SI.