Predictive value of procalcitonin and interleukin 6 in critically ill patients with suspected sepsis

Objective: To evaluate the performance of procalcitonin (PCT), interleukin-6 (IL-6), C-reactive protein, leukocyte count, D-dimer, and antithrombin III at onset of septic episode and 24 h later in prediction of hospital mortality in critically ill patients with suspected sepsis. Design and setting: Prospective, cohort study in two university hospital intensive care units. Patients: 61 critically ill patients with suspected sepsis. Measurements and results: The outcome measure was hospital mortality. Hospital survivors (n = 41) and nonsurvivors (n = 20) differed statistically significantly on day 1 (admission) in PCT, IL-6, SOFA score, and APACHE II score, and 24 h later in PCT, IL-6, and D-dimer values. AT III, CRP, and leukocyte count did not differ. The areas under receiver operating curves showed reasonable discriminative power (> 0.75) in predicting hospital mortality only for day 2 IL-6 (0.799) and day 2 PCT (0.777) values which were comparable to that of APACHE 11 (0.786), and which remained the only independent predictor of mortality. Conclusions: Admission and day 2 IL-6, and day 2 PCT, and day 2 D-dimer values differed significantly between hospital survivors and nonsurvivors among critically ill patients with suspected sepsis. However, in prediction of hospital mortality, only the discriminative power of day 2 PCT and IL-6 values, and APACHE II was reasonable as judged by AUC analysis (> 0.75).