Pre-Rituximab Screening Requirements
Before administering rituximab, you must screen all patients for hepatitis B virus (HBV) infection by measuring HBsAg and anti-HBc, obtain baseline complete blood counts (CBC) with differential and platelets, screen for hepatitis C virus (HCV) and latent tuberculosis (TB), and measure baseline immunoglobulin levels (IgG, IgM, IgA). 1
Essential Pre-Treatment Screening Tests
Mandatory Infectious Disease Screening
Hepatitis B Virus (HBV) - Critical Priority:
- Measure HBsAg (hepatitis B surface antigen) and anti-HBc (hepatitis B core antibody) before initiating rituximab 2, 1
- This is non-negotiable due to the black box warning for HBV reactivation with rituximab 2
- HBV reactivation occurs in approximately 50-64% of patients receiving rituximab without prophylaxis, regardless of underlying disease or HBsAg status 3
- Among HBsAg-positive patients not receiving antiviral therapy, 28.6% experienced HBV flares (with one death reported), and 7.4% of HBsAg-negative/anti-HBc-positive patients experienced reactivation 4
Hepatitis C Virus (HCV):
- Screen with anti-HCV antibodies before starting rituximab 5
- If anti-HCV positive, measure HCV-RNA levels 6
- Patients with detectable HCV-RNA should be referred for antiviral treatment consideration
Latent Tuberculosis:
- Screen for latent TB before initiating rituximab 2, 5
- The 2024 ACR/CHEST guideline explicitly requires TB screening before rituximab initiation 2
Required Laboratory Tests
Complete Blood Count (CBC):
- Obtain CBC with differential and platelet counts prior to the first dose 1
- This establishes baseline hematologic parameters before B-cell depletion
Immunoglobulin Levels:
- Measure baseline IgG, IgM, and IgA levels before administering rituximab 5
- This is important because rituximab can cause hypogammaglobulinemia, and you need baseline values to monitor for this complication
Vaccination Considerations Before Rituximab
Pneumococcal and Influenza Vaccines:
- Vaccinate before rituximab use whenever possible 7
- Rituximab impairs immune response for up to 6 months after treatment 7
- In eight rheumatoid arthritis patients who received flu and PPV23 vaccination 6 days before initiating rituximab, responses were comparable to patients without rituximab 7
- The 2023 ACR vaccination guideline recommends deferring non-live attenuated vaccinations (except influenza) until the next rituximab dose is due, then delaying rituximab for 2 weeks after vaccination 8
Live-Attenuated Vaccines:
- Must be withheld in patients on biological agents like rituximab 7
- If indicated, administer before starting rituximab therapy
Clinical Context and Common Pitfalls
The HBV Screening Gap: Despite clear guidelines, HBV screening rates remain suboptimal in clinical practice. One study found only 60.5% of patients received appropriate HBV screening before rituximab, though rates improved from 14.7% (2006-2009) to 87.1% (2013-2015) 4. Another study in veterans showed only 22% were screened pre-guidelines and 32% post-guidelines 9. Do not skip HBV screening—the consequences can be fatal.
Risk Stratification for HBV:
- HBsAg-positive patients require prophylactic antiviral therapy before rituximab 10
- Anti-HBc-positive/HBsAg-negative patients (resolved HBV) also carry significant reactivation risk with rituximab and may require prophylaxis or close monitoring 6, 10
- Higher baseline HBV DNA levels (≥20 IU/mL vs <20 IU/mL) independently predict HBV reactivation (adjusted HR: 10.9) and HBV-associated hepatitis (adjusted HR: 14.8) 3
Timing Matters: The reactivation risk with rituximab continues to increase even 2 years after therapy 3, making pre-treatment screening and appropriate prophylaxis essential for long-term patient safety.
Progressive Multifocal Leukoencephalopathy (PML) Risk: While not a screening test per se, be aware that PML (including fatal cases) can occur with rituximab 5, 1. Maintain high clinical suspicion for any patient presenting with neurological abnormalities during or after rituximab therapy.