What is the recommended screening process for tuberculosis before initiating rituximab (Rituxan) therapy?

Tuberculosis Screening Before Rituximab Therapy

Screening for latent tuberculosis infection (LTBI) is strongly recommended before initiating rituximab therapy, using a combination of clinical risk assessment, chest X-ray, and preferably an interferon-gamma release assay (IGRA) over tuberculin skin test (TST). 1

Recommended TB Screening Protocol Before Rituximab

Initial Assessment

• Perform a thorough clinical risk assessment for TB exposure, including household contacts, prolonged stay or origin from endemic areas 1
• Screen all patients regardless of risk factors, as rituximab is a biologic disease-modifying antirheumatic drug (bDMARD) 1

Diagnostic Testing

• IGRA (such as QuantiFERON-TB Gold) is preferred over TST, especially in patients who:
  • Have received BCG vaccination (to avoid false positives) 1
  • Are already on immunosuppressive therapy (as TST results may be falsely negative) 1, 2
• Consider performing both TST and IGRA in cases of high suspicion for latent TB and/or in high-endemic countries 1
• Include chest X-ray as part of standard screening, even with negative IGRA or TST 1

Management of Positive Results

• For positive IGRA or TST:
  • Perform chest X-ray and clinical evaluation to rule out active TB 1, 3
  • If chest X-ray shows signs of past TB exposure or active TB, obtain sputum examination 1
  • Refer to specialist for appropriate anti-tubercular treatment if active or latent TB is diagnosed 1

Treatment of LTBI Before Rituximab

• Treatment options for LTBI include:

  • Isoniazid for 9 months (preferred regimen) 1, 3
  • Rifampin for 4 months 1, 4
  • Combination of rifampin/isoniazid for 3-4 months 1
  • Once-weekly therapy of isoniazid plus rifapentine 1

• Rituximab can be initiated or resumed after at least 1 month of LTBI treatment 1, 4

• Monitor liver function tests during LTBI treatment, especially if combined with hepatotoxic drugs 1, 3

Ongoing Monitoring

• Consider annual TB screening in patients who live, travel, or work in situations where TB exposure is likely 1
• For patients who test positive at baseline, monitor for clinical signs and symptoms of recurrent TB rather than repeating tests 1, 4

Special Considerations

• Immunosuppressive therapy can negatively impact IGRA results, with studies showing lower IGRA positive rates in patients on immunosuppressants (13.0% vs 29.6%) 2, 5
• Ideally, TB screening should be performed before starting any immunosuppressive therapy 2, 5
• Rituximab may have a lower risk of TB reactivation compared to TNF inhibitors, with some studies suggesting it could be considered a first-line therapy in areas with high TB prevalence 6

Additional Screening Recommendations

• In addition to TB screening, test for hepatitis B virus (HBV) before starting rituximab, as it carries a risk of HBV reactivation 1
• Consider screening for HIV and hepatitis C virus (HCV) as well 1