The Role of Interferon Gamma Releasing Assays (IGRA) in Screening and Monitoring for Tuberculosis During Anti-TNF Therapy in Patients With Immune-mediated Inflammatory Disease (IMID)

The incidence of inflammatory bowel disease is rising in Hong Kong. Anti-tumor necrosis factor alpha (anti-TNF)-α is effective and increasingly being used for the treatment of patients with refractory disease and complicated disease behaviour. The reactivation of latent tuberculosis (TB) is a well-recognised complication associated with the use of anti-TNF therapy, and most cases occurred in endemic regions. Hong Kong is a region of intermediate TB burden, and the reactivation of latent TB in IMID patients treated with anti-TNF can be a serious problem. Screening has been shown to reduce the incidence of TB, but it remains unclear whether monitoring during anti-TNF therapy is effective. Despite reported efficacy with the current screening strategy, active TB developed in up to 11.4% of patients receiving anti-TNF therapy. There is therefore an urgent need for better disease monitoring and prevention, particularly in regions where TB is endemic.

Part I of this study aims to investigate the role of IGRA in screening for latent TB in IBD patients and control subjects. Part II of this study is a prospective study of serial interferon-gamma release assays (IGRA) for the diagnosis of tuberculosis (TB) infection in patients with immune-mediated inflammatory diseases (IMID) treated with biologics