aHarvard School of Public Health
bDivision of Adolescent/Young Adult Medicine
cDepartment of Pediatrics, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts, USA
Correspondence to Claudia Lavin, MD, Division of General Pediatrics, Children's Hospital Boston, 300 Longwood Avenue, Boston, MA 02115, USA. Tel: +1 617 55 181; fax: +1 617 39 458; e-mail:[email protected]