Competing interests: We have read and understood BMJ policy on declaration of interests and have the following interests to declare: RR is an employee of the Veterans Health Administration, but the views expressed do not necessarily reflect those of the US Department of Veteran Affairs or the US government. She is a board member for Universities Allied for Essential Medicines North America and the American Medical Student Association Foundation and co-chairs the Doctors for America Drug Affordability Action Team, which is supported by the Laura and John Arnold Foundation. MD and JSR receive research support from the FDA for the Yale-Mayo Clinic Center for Excellence in Regulatory Science and Innovation programme. JSR also currently receives research support through Yale University from Johnson and Johnson to develop methods of clinical trial data sharing, and from the Medical Device Innovation Consortium as part of the National Evaluation System for Health Technology, the Agency for Healthcare Research and Quality, the National Heart, Lung and Blood Institute of the National Institutes of Health, and the Laura and John Arnold Foundation. He is an associate research editor at The BMJ. JLS receives research support from the Greenwall Foundation for work related to the topic of this article.