1 Robertson Centre for Biostatistics, University of Glasgow, Glasgow G12 8QQ, UK. Electronic address: [email protected].
2 Department of Cardiology, Portsmouth Hospitals University NHS Trust, Portsmouth, UK; College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK; Faculty of Science and Health, University of Portsmouth, Portsmouth, UK; Department of Renal Medicine, Salford Royal Hospital, Northern Care Alliance NHS Foundation Trust, Salford, UK; Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.