Prediction of microbial infection and mortality in medical patients with fever: Plasma procalcitonin, neutrophilic elastase-alpha(1)-antitrypsin, andlactoferrin compared with clinical variables

Fever suggests the likelihood of severe microbial infection. Abnormal tempe rature, tachycardia, tachypnea, and abnormal white blood cell counts define the systemic inflammatory response syndrome (SIRS). In 300 hospitalized me dical patients with fever, we determined clinical variables and procalciton in, elastase-alpha(1)-antitrypsin, and lactoferrin levels in plasma. Of the patients, 718 had clinical infection (by clinical judgment) and 44% had mi crobial infection (by microbiological testing). SIRS occurred in 95%, and t he 28-day mortality rate was 9%. The sensitivity for predicting microbial i nfection, bacteremia, and mortality was less but the specificity was greate r for supranormal procalcitonin, elastase-alpha(1)-antitrypsin, and lactofe rrin levels than for SIPS. The area under the receiver operating characteri stic curve (AUC) for microbial infection was higher for procalcitonin and e lastase-alpha(1)-antitrypsin levels than for clinical variables and lactofe rrin level. The AUC for bacteremia was also higher for inflammatory factors (>0.70; P < .001) than for clinical variables. The AUC for mortality (P < .05) was 0.79 for the respiratory rate, 0.69 for elastase-alpha(1)-antitryp sin level, 0.65 for heart rate, 0.61 for procalcitonin level, and 0.60 for white blood cell count. In febrile medical patients, plasma procalcitonin a nd elastase-alpha(1)-antitrypsin levels may predict microbial infection and bacteremia better than (and mortality as well as) do clinical symptoms.