What should be checked before starting rituximab?

Pre-Rituximab Screening Requirements

Before starting rituximab, you must screen all patients for hepatitis B virus (HBV) infection by measuring hepatitis B surface antigen (HBsAg) and hepatitis B core antibody (anti-HBc). 1

Comprehensive Pre-Rituximab Screening Protocol

Mandatory Screening Tests

• Hepatitis B Virus (HBV) screening:

  • Hepatitis B surface antigen (HBsAg)
  • Hepatitis B core antibody (anti-HBc)
  • Hepatitis B surface antibody (anti-HBs) is also recommended 2
  • Baseline HBV DNA for patients with positive HBsAg or anti-HBc 2

• Complete Blood Count (CBC):

  • With differential and platelet count 1

• Other recommended screenings:

  • HIV testing 2
  • Hepatitis C virus (HCV) antibody testing, especially with risk factors or elevated liver enzymes 2
  • Tuberculosis screening in endemic areas or high-risk patients 2

Management Based on HBV Screening Results

HBsAg-Positive Patients (Current HBV Infection)

• Refer to hepatologist for antiviral prophylaxis before starting rituximab 2
• Antiviral prophylaxis with entecavir or tenofovir is preferred 2
• Prophylaxis should begin 2-4 weeks before rituximab when possible 2
• Continue antiviral therapy for at least 12 months after completing rituximab 2

HBsAg-Negative, Anti-HBc Positive Patients (Resolved/Occult HBV Infection)

• High risk for reactivation with rituximab 2
• Antiviral prophylaxis recommended rather than monitoring approach 2
• Prophylaxis should continue for at least 18 months after rituximab discontinuation 2
• Monitor HBsAg and HBV DNA for at least 12 months after prophylaxis withdrawal 2

Vaccination Considerations

• Administer necessary vaccines before starting rituximab whenever possible 2
• Rituximab impairs immune response to vaccines for up to 6 months after treatment 2
• If tetanus exposure occurs within 6 months of rituximab treatment, consider tetanus immunoglobulin administration 2

Common Pitfalls and Caveats

1. Inadequate HBV screening: Studies show poor adherence to HBV screening guidelines before rituximab initiation (19-61% of patients not properly screened) 3, 4, 5

2. Fatal consequences of missed HBV reactivation: HBV reactivation can lead to fulminant hepatitis, liver failure, and death 2

3. Delayed reactivation risk: HBV reactivation can occur up to 1-2 years after rituximab discontinuation 2

4. Assuming low risk: Even patients without known risk factors for HBV can have positive screening results 3

5. Monitoring without prophylaxis: For rituximab specifically, prophylaxis is superior to monitoring alone due to high reactivation risk 2

Special Considerations

• In patients receiving rituximab for HCV-associated glomerulonephritis, assessment for HBV coinfection is essential before initiating therapy 2

• For patients receiving lower doses of rituximab (e.g., 200mg in kidney transplantation), reactivation risk may be lower but screening is still required 6

• Consultation with a hepatologist is recommended for all HBsAg or anti-HBc positive patients prior to rituximab initiation 2

By implementing this comprehensive screening protocol before initiating rituximab, you can significantly reduce the risk of HBV reactivation and its potentially fatal consequences.