From the Guidelines
Before initiating biologic therapy in a patient with rheumatoid arthritis, tuberculosis (TB) screening with either a tuberculin skin test (TST) or interferon-gamma release assay (IGRA) is mandatory, as recommended by the 2015 American College of Rheumatology guideline 1. The choice between TST and IGRA depends on the patient's history of Bacillus-Calmette-Guérin (BCG) vaccination, with IGRA preferred in patients who have received BCG vaccination due to the high false-positive rate of TST in this population 1. Key considerations in TB screening include:
- Identifying risk factors for latent TB infection (LTBI), such as close contacts of persons known or suspected to have active TB, foreign-born persons from areas with a high incidence of active TB, and residents or employees of congregate settings whose clients are at increased risk for active TB 1.
- Performing a chest radiograph and sputum examination for acid-fast bacilli (AFB) smear and culture if the initial or repeat TST or IGRA is positive, to rule out active TB 1.
- Considering referral to a TB specialist for further evaluation and treatment if latent or active TB is diagnosed 1.
- Monitoring patients who test positive for TST or IGRA at baseline for clinical signs and symptoms of recurrent TB, as repeating tests will not help in the diagnosis of recurrent TB 1. Additionally, other essential screening tests before initiating biologic therapy include hepatitis B and C serologies, complete blood count (CBC), comprehensive metabolic panel (CMP), and baseline immunoglobulin levels, as well as screening for a history of multiple sclerosis or demyelinating disorders, congestive heart failure, and recent infections or malignancies 1. Updating vaccination status before starting therapy, with live vaccines administered at least 2-4 weeks prior to beginning biologics, and considering HIV testing in high-risk patients, are also crucial steps in the screening process 1. These screening tests help identify potential contraindications and establish baseline values to monitor during treatment, reducing the risk of serious adverse events associated with biologic therapy, which suppresses the immune system while targeting specific inflammatory pathways involved in rheumatoid arthritis. It is also important to note that patients who are immunosuppressed may have false-negative results, and consideration should be given to repeating screening tests with TST or IGRA in these cases 1. Annual testing for LTBI is recommended for patients who live, travel, or work in situations where TB exposure is likely, while they continue treatment with biologics 1.
From the Research
Screening Lab Tests for Biologic Therapy in Rheumatoid Arthritis
- Before initiating biologic therapy in a patient with rheumatoid arthritis, several screening lab tests must be done to reduce the risk of adverse events, including tuberculosis (TB) reactivation and hepatitis B reactivation 2, 3, 4.
- The screening tests include:
- Tuberculin skin test (TST) or interferon gamma release assay (IGRA) to detect latent TB infection 3, 4.
- Hepatitis B test to detect hepatitis B virus (HBV) infection 4, 5.
- Human immunodeficiency virus (HIV) test to detect HIV infection 4.
- Varicella zoster virus (VZV) antibody test to detect VZV infection 4.
- Chest X-rays and laboratory tests, including complete blood count and liver function tests 4.
- These screening tests are essential to identify patients at risk of TB reactivation, hepatitis B reactivation, and other infections, and to provide prophylaxis or treatment before initiating biologic therapy 2, 3, 4.
- The choice of biologic agent and the timing of biologic therapy initiation should be based on the patient's individual risk factors and the results of the screening tests 2, 3, 4.