Douglas was an outstanding clinical scientist with an international reputation in the pathogenesis and treatment of inflammatory joint diseases. His major focus was centred on the role of synovial fibroblasts in driving inflammation and tissue damage in rheumatoid arthritis.
Along with his wife, Professor Ursula Fearon, he reported novel findings including the role of innate immune proteins, such as serum amyloid A, and hypoxia in driving the auto aggressive phenotype of these cells. He also made important discoveries related to using a more personalised approach to treatments of conditions such as rheumatoid arthritis and psoriatic arthritis. He supervised a large number of MD and PhD students many of whom are now active in clinical and laboratory-based research
Douglas was recognised for his pioneering achievements in rheumatology, commitment to clinical and research excellence and dedication to patient care. He was the first recipient of the Royal College of Surgeons in Ireland (RCSI) Vice Chancellor's Outstanding Achievement Award in December 2023 and a lifetime achievement award at the Irish Society for Rheumatology Conference in Dublin in October 2023.