INTERLEUKIN-6 AND ACUTE-PHASE PROTEIN CONCENTRATIONS IN SURGICAL INTENSIVE-CARE UNIT PATIENTS - DIAGNOSTIC SIGNS IN NOSOCOMIAL INFECTION

Objective: To determine the value of serum concentrations of interleuk in-6 (IL-6), C-reactive protein, and glycosylation of alpha1-acid glyc oprotein as tools for diagnosing nosocomial infection in surgical inte nsive care unit (ICU) patients. Design: Prospective, consecutive entry study of patients with an anticipated stay of at least 24 hrs in a su rgical ICU. Setting. University hospital, a major provider of acute su rgical care. Patients: One hundred four consecutive patients admitted to the surgical ICU between March and June 1990. Measurements: Concent rations of IL-6, C-reactive protein, and glycosylation of alpha1-acid glycoprotein were measured on days 1 and 6 after ICU admission. Clinic al evaluation for infection was performed daily in a blinded fashion, i.e., without knowing the results of the acute-phase parameters. Main Results. On day 6 after surgery or trauma, nosocomial infection could be ascertained in 13 cases. The clinical parameter of fever >38-degree s-C had a sensitivity of 54% and a specificity of 90% to demonstrate n osocomial infection. Infected patients showed increased concentrations of IL-6 (p < .001), C-reactive protein (p < .001), and increased reac tivity of alpha1-acid glycoprotein to concanavalin A (p < .001) compar ed with patients without infections. By choosing appropriate cutoff va lues, IL-6 determinations had the highest specificity (97%), and C-rea ctive protein values had the highest sensitivity (85%) for diagnosing nosocomial infections. In uninfected patients, 81% of the IL-6 values, but only 29% of the C-reactive protein values, were back to the norma l range on day 6 after injury. Conclusion: Due to the rapid normalizat ion after trauma, a single measurement of the serum IL-6 concentration may be useful to support or refute the clinical suspicion of nosocomi al infection.