Key Point

Decreases in procalcitonin or C-reactive protein independently predict survival in ventilator-associated pneumonia.

RIO GRANDE DO SUL, BRAZIL—The effectiveness of antimicrobial therapy in treating ventilator-associated pneumonia (VAP) is usually assessed after three days with microbiological tests and clinical parameters. However, day 4 procalcitonin and C-reactive protein measurements can also be used to provide an accurate prognosis, found a recent study.¹

Declines in those measurements from baseline independently predicted greater survival among 75 VAP patients. "Considering the mortality rate of VAP, it is highly desirable to have early laboratorial markers to predict survival or the necessity to reassess initial empirical antimicrobial therapy," remarked the authors.

STUDYING PREDICTORS OF SURVIVAL IN PATIENTS WITH VAP

The study subjects were admitted to the ICU for VAP during a two-year period; pneumonia was considered ventilator-associated when it occurred after 48 hours of mechanical ventilation and was believed not to have been incubating before the patient was placed on the ventilator. Patients who lived 28 days after VAP diagnosis or who were discharged before day 28 were considered survivors. Those who died before day 28 were classified as nonsurvivors.

Antibiotic therapy for VAP was deemed adequate when the agent or agents prescribed covered all of the pathogens isolated from blood or quantitative endotracheal aspirate cultures and when therapy resulted in negative cultures. Pseudomonas aeruginosa and Staphylococcus aureus were the pathogens that were isolated most frequently.

Of the patients, whose mean age was 61, there were 46 survivors and 29 deaths. The survivors were noticeably younger; their average age was 58, versus 64 for the nonsurvivors. Septic shock developed in nearly 52% of the nonsurvivors, compared to just 4.4% of the survivors.

In a univariate model, decreased day 4 procalcitonin and C-reactive protein values were associated with odds ratios for survival of 5.67 and 3.78, respectively. A decreased Sepsis-Related Organ Failure Assessment (SOFA) score on day 4 also predicted survival, as shown by an odds ratio of 3.08. Only reductions in day 4 procalcitonin and C-reactive protein significantly predicted survival in a multivariate model, however; those reductions were associated with odds ratios for survival of 4.43 and 7.4, respectively.

ADEQUATE ANTIBIOTIC THERAPY NOT A SIGNIFICANT FACTOR IN SURVIVAL

Surprisingly, there was no correlation between the adequacy of antibiotic therapy and survival. Among the 20 patients whose antibiotic therapy was considered inadequate and the 55 patients given adequate therapy, survival was 50% and 65.5%, respectively, but this difference was not significant.

The relationship observed between procalcitonin, C-reactive protein, and survival in VAP may reflect a reduction in the exposure of survivors to bacterial toxins, suggested the authors. "Further studies with a larger sample are necessary to establish if a combination of markers kinetics can be used to guide antimicrobial therapy, especially in cases where microorganisms are not identified," the investigators said.

—Timothy Begany

Reference
1. Seligman R, Meisner M, Lisboa TC, et al. Decreases in procalcitonin and C-reactive protein on the fourth day of treatment are strong predictors of survival in ventilator-associated pneumonia. Crit Care. 2006 Sept 6;10:R125 [Epub ahead of print].

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