“…6,33 These institution-based criteria were reasonably chosen by the authors, and they were very much similar to the CDC/NHSN criteria. In addition, 10 of the participating studies were characterized as prospective cohort studies, 24,26,28,30,31,35,37,40,41,44 5 were characterized as retrospective cohort studies, 25,33,36,38,39 and 6 were characterized as case-control studies. 6,29,32,34,42,43 However, we decided that the included case-control studies should ultimately be classified as either retrospective cohorts 6,32,34,42 or as prospective cohorts 29,43 because they actually measured outcomes after prospective or retrospective surveillance of matched BSI and non-BSI children until discharge or death.…”