1. Sunderland Royal Hospital; Kayll Road Sunderland UK
2. University of Edinburgh; Centre for Population Health Sciences; Edinburgh UK EH8 9AG
3. Queen Elizabeth Hospital; Department of General and Vascular Surgery; Queen Elizabeth Avenue Sheriff Hill Gateshead Tyne and Wear UK NE9 6SX
4. Freeman Hospital; Northern Vascular Centre; Newcastle upon Tyne UK NE7 7DN