Do transfusions cause necrotizing enterocolitis? The complementary role of randomized trials and observational studies

A systematic review and a meta-analysis of the published literature on the association between transfusions in newborns and the occurrence of transfusion-associated necrotizing enterocolitis were performed. We discuss the differences between findings in randomized trials, and the results of observational studies that first explored this putative link. We suggest the following framework: where observational studies play a hypothesis generating- role for therapies and harm, and randomized studies allow an acid test of that hypothesis. It is acknowledged that not all questions can be subject to a randomized evaluation, but argued that this particular association is amenable to such a test.