The behavior and diagnostic utility of procalcitonin and five other inflammatory molecules in critically ill patients with respiratory distress and suspected 2009 influenza a H1N1 infection

OBJECTIVES: During the 2009 influenza A H1N1 pandemic, it became difficult to differentiate viral infections from other conditions in patients admitted to the intensive care unit. We sought to evaluate the behavior and diagnostic utility of procalcitonin, C-reactive protein and four other molecules in patients with suspected 2009 Influenza A H1N1 infection. METHODS: The serum levels of procalcitonin, C-reactive protein, tumor necrosis factor α, interferon γ, interleukin 1β, and interleukin 10 were tested on admission and on days 3, 5, and 7 in 35 patients with suspected 2009 H1N1 infection who were admitted to two ICUs. RESULTS: Twelve patients had confirmed 2009 influenza A H1N1 infections, 6 had seasonal influenza infections, and 17 patients had negative swabs. The procalcitonin levels at inclusion and on day 3, and the C-reactive protein levels on day 3 were higher among subjects with 2009 influenza A H1N1 infections. The baseline levels of interleukin 1β were higher among the 2009 influenza A H1N1 patients compared with the other groups. The C-reactive protein levels on days 3, 5, and 7 and procalcitonin on days 5 and 7 were greater in non-surviving patients. CONCLUSION: Higher levels of procalcitonin, C-reactive protein and interleukin-1β might occur in critically ill patients who had a 2009 H1N1 infection. Neither procalcitonin nor CRP were useful in discriminating severe 2009 H1N1 pneumonia. Higher levels of CRP and procalcitonin appeared to identify patients with worse outcomes.