Interferon-Gamma Release Assay for TB Suggested Before Prescribing Anti-TNF Agents for IBD: Presented at DDW

NEW ORLEANS -- May 5, 2010 -- Patients diagnosed with inflammatory bowel disease (IBD) should undergo sensitive testing for latent tuberculosis (TB) before they begin biologic therapy, researchers suggested here at the Digestive Diseases Week (DDW) 2010.

"We know that the tuberculosis skin test may not be the most sensitive test available, and when you are giving biologic agents that may be immunocompromising we want to make sure these patients are not at risk for the emergence of a serious infection such as tuberculosis," said Kay Greveson, Centre for Gastroenterology, Royal Free Hospital, London, United Kingdom, on May 4.

"Conventional screening involves assessment of risk factors, chest radiograph, and tuberculin skin testing," Greveson said. "This can be difficult to interpret in immunosuppressed subjects. Tuberculosis interferon-gamma assays may detect Mycobacterium tuberculosis infection with greater specificity and possibly sensitivity."

The research team performed a retrospective review of patients with IBD either considered for anti-tumour necrosis factor (TNF) agents or who were already using infliximab and adalimumab and who were assessed for evidence of TB infection with interferon-gamma release assay testing as part of their screening protocol.

Greveson said that 100 patients were tested using interferon-gamma release assays, and 3 patients had positive reactions, while 3 others had indeterminate responses.

Of those with positive reactions, 1 patient had been successfully treated for pulmonary TB and had already been on adalimumab therapy for IBD. After a risk/benefit analysis was performed, the patient remained on treatment. A second patient was treated for latent TB infection prior to starting anti-TNF therapy. The third patient developed a TB infection 44 months into treatment with a TNF agent and after visiting TB-endemic regions in South America.

Two of the 3 patients with indeterminate results had no reaction when they retook the test 2 weeks later. The third patient had another indeterminate test.

"We suggest that large scale evaluation of interferon-gamma release assays as part of a tuberculosis screening strategy prior to anti-TNF agents should be undertaken," Greveson said. "It will be particularly important to include health-economic cost-benefit analyses in low tuberculosis incidence areas."

Digestive Disease Week 2010 is cosponsored by the American Association for the Study of Liver Diseases (AASLD), the American Gastroenterological Association (AGA), the American Society for Gastrointestinal Endoscopy (ASGE), and the Society for Surgery of the Alimentary Tract (SSAT).

[Presentation title: Screening Patients Initiating Anti-TNF Agents for Mycobacterial Infection Using Interferon-Gamma Release Assays (IGRA): The Experience of a Large Inflammatory Bowel Disease Service. Abstract T1272]