Azathioprine and TB Risk: Management Guidelines

Risk Assessment for TB Reactivation with Azathioprine

Azathioprine monotherapy does not significantly increase TB reactivation risk when compared with placebo alone 4
The combination of azathioprine with anti-TNF agents increases the risk of TB reactivation 13-fold compared to anti-TNF monotherapy 1, 5

The European Crohn’s and Colitis Organisation recommends that TB screening is not routinely required before starting azathioprine monotherapy 4, 6
The British Association of Dermatologists suggests that careful selection of patients is still recommended prior to starting azathioprine, as reactivation of latent infections such as tuberculosis has been reported in rare cases 7, 8
If azathioprine will be used in combination with anti-TNF agents or JAK inhibitors, the American Gastroenterological Association recommends that TB screening becomes essential 1, 2
TB screening should include patient clinical data and epidemiological risk factors assessment 3, chest X-ray 2, and tuberculin skin test (TST) or interferon-gamma release assay (IGRA) or both, according to local availability and national recommendations 4

For patients on azathioprine monotherapy, the American College of Gastroenterology recommends no specific LTBI treatment 4
For patients on combination therapy (azathioprine + anti-TNF), the European League Against Rheumatism recommends screening for LTBI before initiating combination therapy 1, 4 and treating LTBI if detected before starting anti-TNF therapy 4
The Centers for Disease Control and Prevention suggest considering annual re-screening for patients with higher TB risk (living or traveling in intermediate or high TB incidence areas) 4

The World Health Organization notes that the risk of TB in patients on immunosuppressive therapy depends on the local disease burden of TB 4
The European Crohn’s and Colitis Organisation recommends that TB screening should ideally be performed before starting any immunosuppressive treatment, as both TST and IGRA sensitivity are negatively affected by immunosuppressive therapy 1, 4