From the *Division of General Pediatrics and Adolescent Medicine, Department of Pediatrics, Johns Hopkins School of Medicine, Baltimore, MD; and †Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD
Conflicts of interest and sources of funding: none declared.
Correspondence: Jonathan M. Ellen, MD, Department of Pediatrics, Johns Hopkins School of Medicine, Mason F. Lord, Center Tower, 5200 Eastern Ave., Suite 4200, Baltimore, MD 21224. E-mail: firstname.lastname@example.org.
Received for publication March 30, 2012, and accepted April 4, 2012.