Competing interests: Uniform disclosure of potential conflicts of interest: all authors have completed the ICMJE unified competing interest form (available from the corresponding author) and declare (1) David Moher received grants for this work from Johnson & Johnson, BMJ, and American Society for Clinical Oncology; Kenneth Schulz and Douglas Altman received support for travel to meetings for this work from Johnson & Johnson, BMJ, and American Society for Clinical Oncology; (2) Kenneth Schulz and Douglas Altman had travel expenses reimbursed by the EQUATOR Network; Kenneth Schulz has received honoraria for delivering educational presentations for the American Board of Obstetrics and Gynecology Foundation for Excellence in Women’s Health Care, Ortho-McNeil Janssen Scientific Affairs, and the American College of Obstetrics and Gynecology; and has done consultancy for Wyeth. All authors also declare (3) no spouses, partners, or children with relationships with commercial entities that might have an interest in the submitted work; (4) no non-financial interests that may be relevant to the submitted work.