OTA 2005 Posters
Scientific Poster #14 Polytrauma/Injury Prevention
Correlation Between IL-6 Levels and the SIRS Score: Can an IL-6 Cutoff Predict a SIRS State?
Background: With greater understanding of the host response to trauma, increasing emphasis is being placed on assessment of the inflammatory status of the patient. Serum inflammatory cytokines, particularly IL-6, have been used as an adjunct to this assessment. A measurement of >500 pg/dL in combination with early surgery has been associated with adverse outcome. Another method of estimating the patient's inflammatory status is the systemic inflammatory response score (SIRS). This uses a combination of simple laboratory and clinical measurements (leukocyte count, temperature, pulse rate, and respiratory rate) to give a score of 0 to 4; a score of 2 or more declares the patient in a "SIRS state". No study has previously examined the relationship between IL-6 levels and SIRS scoring.
Methods: In patients with femoral shaft fractures, serum IL-6 levels and relevant clinical parameters were recorded prospectively on admission and on days 1, 3, 5, and 7. Clinical course and complications were documented. Nonparametric tests were used to assess relationships between variables, and ROC curves were used to examine their predictive values. Significance was assumed at the P<0.05 level.
Results/Discussion: Fifty patients (37 male) were included in this study. The mean age was 32.8 years (range, 15 to 67) and the median new injury severity score (NISS) was 31.5 (range, 9 to 75). Results for the SIRS score and IL-6 levels are shown in Chart 1. Both the IL-6 and SIRS score recorded on admission correlated strongly with the patients' NISS (P<0.001). The presence of a "SIRS state" on admission, day 1, and day 3 positively correlated with the IL-6 measurement from the same period (P<0.001). Stronger correlations were seen closer to admission, with loss of statistical significance on days 5 and 7. ROC curve analysis revealed elevated IL-6 to be significantly diagnostic of a "SIRS state" (P<0.001) at all times; again, however, test efficacy improved with later values excluded. On days 0 and 1, an IL-6 value above 200 pg/dL diagnosed a "SIRS state" with an 83%
sensitivity and a 75% specificity (area under ROC curve 0.83, P<0.0001).
A SIRS state on admission was associated with a significantly increased
risk of complication (pneumonia, multiple organ failure, death)68% versus
18%, P<0.001. An IL-6 >200 pg/dL on days 0 or 1 was also associated
with an increased rate of complication55% versus 10% (P<0.05).
Conclusion/Significance: The IL-6 concentration and SIRS score are useful adjuncts to clinical evaluation of the injured patient. In the early phase they are closely correlated with the NISS and each other. A cutoff value of 200 pg/dL was shown to be significantly diagnostic of a "SIRS state". Significant correlations between adverse events and both the IL-6 level and SIRS state are demonstrated.