Usefulness of procalcitonin serum level for the diagnosis of bacteremia

The predictive value of procalcitonin serum levels to detect or rule out ba cteremia was investigated prospectively in a case-control study with 200 ho spitalized adults from whom blood samples were taken for culture. Fifty bac teremic patients (cases) had higher procalcitonin serum levels than the 150 controls with sterile blood cultures (11.7 vs. 0.7 ng/ml; P=0.0001), a dif ference that remained significant after controlling for potential confounde rs in multivariate analysis. At cut-off values of 0.5 and 0.2 ng/ml, the se nsitivity of procalcitonin was 56 and 92%, and the specificity was 83 and 4 3%, respectively. These results yielded low positive (22 and 12%) and high negative predictive values (96 and 99%), reflecting primarily the low preva lence of bacteremia among patients who undergo blood cultures in hospitals (low pretest probability). Although caution is mandatory when using such ma rkers at the individual level, procalcitonin, possibly together with other parameters, could nonetheless prove useful in future studies to rapidly rul e out bacteremia.