Is cytomegalovirus reactivation increasing the mortality of patients with severe sepsis?

Cytomegalovirus (CMV) is a ubiquitous virus present in approximately two-thirds of the healthy population. This virus rarely causes an active disease in healthy individuals, but it is among the most common opportunistic infections in immunocompromised patients such as solid organ transplant recipients, patients receiving chemotherapy for cancer or patients with human immunodeficiency virus. Critically ill patients who are immunocompetent before intensive care unit admission may also become more prone to develop active CMV infection if they have prolonged hospitalizations, high disease severity, and severe sepsis. The development of active CMV infection in these critically ill patients has been associated with a significantly higher risk of death in several previous studies. The present issue of Critical Care brings a new study by Heininger and colleagues in which the authors found that patients with severe sepsis who developed active CMV infection had significantly longer intensive care unit and hospital stays, prolonged mechanical ventilation, but no changes in mortality compared to patients without CMV infection. We discuss the possible reasons for their findings (for example, selection bias and low (20%) statistical power to detect mortality endpoints), and also perform an update of our previous meta-analysis with the addition of Heininger and colleagues' study to verify whether the higher mortality rate with CMV holds. Our updated meta-analysis with approximately 1,000 patients shows that active CMV infection continues to be associated with a significant 81% higher mortality rate than that in critically ill patients without active CMV infection.