Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare the following: BG is chair of the HealthTech Advisory Board reporting to the Secretary of State for Health and Social Care. He has received research funding from the Laura and John Arnold Foundation, the Wellcome Trust, the Oxford Biomedical Research Centre, the NHS National Institute for Health Research School of Primary Care Research, the Health Foundation, NHS England, and the World Health Organisation; some of this funding is to work on NHS data, including open analysis of NHS prescribing data; he also receives personal income from speaking and writing for lay audiences on the misuse of science. BMK is employed by NHS England working on medicines policy and clinical lead for primary care medicines data. The views expressed are those of the authors and not necessarily those of the NIHR, NHS England, or the Department of Health and Social Care.