Professor Thomas is Professor of Epidemiology and Research Methods. He has an international portfolio of research in Europe, Africa and Asia investigating in the fields of cardiometabolic disease epidemiology and patient management with a particular focus on atrial fibrillation care pathways, air pollution and lifestyle exposures. Major recent or ongoing studies include the NIHR Global Group in Atrial Fibrillation management, Brazil, China, and Sri Lanka for which he is co-Director; Elderly Health Centres Study (air pollution, lifestyle, mortality outcomes), Hong Kong; the 30,000 plus Guangzhou Biobank Cohort Study (lifestyle, chronic disease outcomes), China; and the first hard outcome primary and secondary prevention trial assessing the effectiveness of a PolyPill (PolyIran: CVD, mortality outcomes) using a novel nested design. Recent funding includes a type II hybrid effectiveness-implementation cluster randomised trial of a digital multi-component intervention to IMPROVE the care of older people living with diabetes and chronic kidney disease in primary care, and, implementation of digitally integrated care pathways for multiple-long-term-conditions management in primary care, Sri Lanka (DIGIPATHS Study).

Professor Thomas has published over 300 in indexed, peer-reviewed journals and has an H-index over 70 (Google Scholar) with over 30,000 citations. His research is underpinned by sustained funding of over £50 million; almost £30 million as co/CI. He is the Deputy Chair for the Health and Care Research Wales Integrated Funding scheme, the Health and Social Care services and Public Health Arm.

Professor Thomas has an active teaching role in under- and postgraduate studies. He is the Co-Director, Master of Health Research Methods (HRM) Programme.