The initial database search identified 524 English-language and 77 non-English-language studies. After review of the title and abstract and manual search for bibliographies of the potentially relevant articles, 26 studies were selected for fulltext review . Ten studies were excluded after full-text review because: CMV infection was diagnosed based on an increase in titers [19] [20] [21] [22] [23] [24] ; the study was not explicitly conducted in the ICU [25] ; or the rate of CMV infection was not reported [26, 27] . Data from one institution with overlapping study cohorts in two articles were analyzed only once to avoid duplication in the results [16, 28] . We found three studies in which CMV disease was sought as etiology of acute respiratory distress syndrome (ARDS) or ventilator-associated pneumonia (VAP) [29] [30] [31] . Considering that CMV disease (organspecific symptoms or signs plus the detection of CMV in organ biopsy samples by histopathology) is a distinct entity with worse outcomes than CMV infection, the data from these studies were summarized separately.