The Role of IGRA in Screening and Monitoring for TB During Anti TNF Therapy in Patients With 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

Inclusion criteria

• patients aged 18 years or older
• patients with a diagnosis of Crohn's disease (CD) or ulcerative colitis (UC) for at least 3 months defined by histology or radiology

Exclusion criteria

• Patients with a previous history of TB
• Patients with a positive IGRA or CXR suggesting latent tuberculosis prior to commencement of therapy