ACKNOWLEDGEMENTS
We thank Marci Fjelstad and Amy Watson from the PECARN Data Coordinating Center for their assistance; the research coordinators in PECARN, without whom this study would not have been possible; the clinicians in PECARN who enrolled children in this study; the members of the data and safety monitoring board (Roger Lewis, M.D., Ph.D., Jeffrey Blumer, M.D., Ph.D., Andrew Bremer, M.D., Ph.D., Thomas Cook, Ph.D., and Beth Slomine, Ph.D., A.B.P.P.); and the members of the study outcome adjudication committee (Kathleen Meert, M.D., Jerry Zimmerman, M.D., Ph.D., and Robert Hickey, M.D.).