Serum levels of interleukin‐6 may predict organ dysfunction earlier than SOFA score

Aim To investigate the clinical utility of interleukin‐6 ( IL ‐6), procalcitonin ( PCT ), and C‐reactive protein ( CRP ) as predictive markers in consideration of the time‐course changes in critically ill patients with organ dysfunction. Methods Serum levels of IL ‐6, PCT , CRP , and Sequential Organ Failure Assessment ( SOFA ) scores were measured sequentially in 92 patients during their initial 5 days following admission to the intensive care unit. Maximum values were analyzed. Patients were assigned to a low ( ≤ 8), intermediate ( > 8 and ≤ 16), or high ( > 16 and ≤ 24) SOFA score group. Results There were significant differences in the maximum serum levels of IL ‐6 and PCT among the three SOFA score groups ( IL ‐6, P < 0.0001; PCT , P = 0.0004). Specifically, comparisons between the groups revealed significant differences in IL ‐6 levels (low versus intermediate, P = 0.0007; intermediate versus high, P = 0.0010). The probability of patients with the maximum value was greatest on day 1 (56.5%) for IL ‐6, on day 1 (39.1%) or day 2 (38.0%) for PCT , on day 3 (39.1%) for CRP , and on day 1 (43.5%) for SOFA score. The median (interquartile range) peak day of IL ‐6 was day 1 (1–2), which was significantly earlier than that of SOFA score at day 2 (1–3) ( P = 0.018). Conclusion Serum levels of IL ‐6 reflected the severity of organ dysfunction in critically ill patients most accurately compared to PCT and CRP . Interleukin‐6 elevated soonest from the insult and reached its peak earlier than SOFA score.