From the Guidelines
The next step in management for this 50-year-old male with late-onset rheumatoid arthritis on methotrexate and hydroxychloroquine who has a positive Interferon-Gamma Release Assay (IGRA) is to initiate treatment for latent tuberculosis infection (LTBI). The recommended regimen is isoniazid 300mg daily for 9 months, or alternatively, rifampin 600mg daily for 4 months, as suggested by the most recent guidelines 1. Before starting treatment, a chest X-ray should be performed to rule out active tuberculosis. The patient can continue methotrexate and hydroxychloroquine during LTBI treatment, but liver function tests should be monitored monthly due to the hepatotoxic potential of both isoniazid and methotrexate, as indicated by previous studies 1. This treatment is crucial because immunosuppressive medications like methotrexate increase the risk of TB reactivation in patients with latent infection. The positive IGRA indicates the patient has been exposed to TB and harbors the bacteria in a dormant state. Treating LTBI significantly reduces the risk of progression to active TB disease, which would be more difficult to treat and potentially life-threatening, especially in an immunocompromised patient. Key considerations in the management of rheumatoid arthritis, as outlined in recent recommendations 1, emphasize the importance of early diagnosis, treatment targets, and the role of methotrexate as a first-line therapy, but the immediate priority in this case is addressing the latent tuberculosis infection to prevent its reactivation. Regular monitoring and adjustments to the treatment plan may be necessary to ensure the best outcomes for the patient, considering both the rheumatoid arthritis and the latent tuberculosis infection, as guided by the principles of managing chronic diseases like rheumatoid arthritis 1.
From the Research
Next Steps in Managing Late-Onset Rheumatoid Arthritis with Positive IGRA Result
- The patient is currently on methotrexate and hydroxychloroquine (HCQ) for late-onset Rheumatoid Arthritis (RA) and has a positive Interferon-Gamma Release Assay (IGRA) result, indicating latent tuberculosis infection (LTBI) 2.
- According to expert consensus, patients with RA who are at high risk of developing active tuberculosis (TB) should receive tuberculosis preventive treatment (TPT) 3.
- For patients with LTBI, the recommended TPT regimens include isoniazid monotherapy for 6 or 9 months, rifampicin monotherapy for 4 months, weekly rifapentine plus isoniazid for 3 months (3HP regimen), and daily rifampicin plus isoniazid for 3 months (3HR regimen) 2.
- A study found that methotrexate combined with isoniazid treatment for latent tuberculosis is well tolerated in patients with rheumatoid arthritis, with minimal risk of hepatotoxicity 4.
- However, another study suggested that withholding prophylaxis prior to anti-TNF therapy may be reasonable for low-risk elderly RA patients with a TST finding of 5-9 mm, although the decision is sensitive to patient preferences 5.
- In patients treated with TNF-α antagonists and with LTBI, a 3HR or 3H2P2 regimen is recommended for TPT, and the timing of TPT should be based on clinical assessment 3.
Considerations for TPT in Patients with RA
- The risk of TB reactivation in patients with RA on methotrexate and HCQ should be assessed, and TPT should be considered if the risk is high 3.
- The choice of TPT regimen should be based on the patient's clinical evaluation, including their risk of TB reactivation, liver function, and potential drug interactions 2.
- Close monitoring of liver function tests (LFT) is recommended for patients receiving TPT, especially those on isoniazid and methotrexate 4.