1 Department of Non-Communicable Disease Epidemiology, London School of Hygiene & Tropical Medicine, London WC1 7HT, UK. Electronic address: rohini.mathur@lshtm.ac.uk.
2 Department of Non-Communicable Disease Epidemiology, London School of Hygiene & Tropical Medicine, London WC1 7HT, UK.
3 The DataLab, Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK.
4 Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London WC1 7HT, UK.