Additional considerations in immunocompromised patients

Immune compromise is a risk factor for reactivation of TB. If latent TB is diagnosed in an immunocompromised patient, treatment is recommended.

The benefits of treating latent TB are likely to extend to those in whom immunosuppressive therapy is being planned; for example, patients being considered for organ or haematopoietic stem cell transplant or who will be starting immunomodulatory therapy for connective tissue disease.

Consider the following when assessing and managing latent TB in immunocompromised patients (or those expected to start immunosuppressive therapy):

• Diagnosis is complicated because investigations such as a tuberculin skin test (TST) or TB-specific interferon gamma release assay (IGRA) often produce false-negative results in immunocompromised patients.
• Active TB may be more difficult to rule out in these patients given the higher rates of extrapulmonary infection.
• Timing of therapy—if completion of treatment for latent TB is required before listing for organ or haematopoietic stem cell transplant, consider one of the shorter duration regimens (see Treatment of latent tuberculosis). However, in many cases completion of treatment before starting immunosuppressive therapy is not required or not possible. If immunosuppressive therapy can be delayed, one approach is to start treatment for latent TB a month before starting immunosuppressive therapy; this allows time to monitor for adverse effects of TB therapy (eg hepatotoxicity), and, should an adverse effect occur, makes it easier to identify the causative drug.
• Consider potential drug interactions, particularly with rifampicin and calcineurin inhibitors (ciclosporin, tacrolimus).
• Active TB may develop despite treatment of latent TB—consider the possibility of active TB in an immunocompromised patient with fever of unclear origin.
• People treated for latent TB can acquire TB again—for example, migrants who return to countries where TB is endemic to visit family and friends.