Procalcitonin, interleukin 6 and systemic inflammatory response syndrome (SIRS): early markers of postoperative sepsis after major surgery

Background. Patients who undergo major surgery for cancer are at high risk of postoperative sepsis. Early markers of septic complications would be useful for diagnosis and therapeutic management in patients with postoperative sepsis. The aim of this study was to investigate the association between early (first postoperative day) changes in interleukin 6 (IL-6), procalcitonin (PCT) and C-reactive protein (CRP) serum concentrations and the occurrence of subsequent septic complications after major surgery. Methods. Serial blood samples were collected from 50 consecutive patients for determination of IL-6, PCT and CRP serum levels. Blood samples were obtained on the morning of surgery and on the morning of the first postoperative day. Results. Sixteen patients developed septic complications during the first five postoperative days (group 1), and 34 patients developed no septic complications (group 2). On day 1, PCT and IL-6 levels were significantly higher in group 1 (P-values of 0.003 and 0.006, respectively) but CRP levels were similar. An IL-6 cut-off point set at 310 pg ml(-1) yielded a sensitivity of 90% and a specificity of 58% to differentiate group 1 patients from group 2 patients. When associated with the occurrence of SIRS on day 1 these values reached 100% and 79%, respectively. A PCT cut-off point set at 1.1 ng ml(-1) yielded a sensitivity of 81% and a specificity of 72%. When associated with the occurrence of SIRS on day 1, these values reached 100% and 86%, respectively. Conclusions. PCT and IL-6 appear to be early markers of subsequent postoperative sepsis in patients undergoing major surgery for cancer. These findings could allow identification of postoperative septic complications.