Background:

Tuberculin is the globally accepted delayed cutaneous hypersensitivity test for the diagnosis of latent tuberculosis. The alteration of cellular immunity induced by disease-modifying drugs used in rheumatoid arthritis may give a false negative result, also known as cutaneous anergy. There are no studies that determine the frequency of anergy in patients with rheumatoid arthritis and on immunosuppressive therapy.

Objective:

To determine the frequency and possible factors associated with cutaneous anergy in a group of patients with rheumatoid arthritis and on immunosuppressive therapy.

Methods:

Cross-sectional analytical observational study including 100 patients with rheumatoid arthritis on immunosuppressive therapy. They were tested for delayed cutaneous hypersensitivity with tuberculin, and a control test with tetanus toxoid. The non-reactivity of both tests was defined as anergy.

Results:

The overall frequency of cutaneous anergy was 9% (n = 11). It occurred in 33% of men versus 6% of women. The mean age was 57 years, and 89% were over 50 years-old. Being female behaved as a protective variable for the generation of anergy, OR 0.795 [95% CI, 0.658 - 0.959, P<.05]. All patients with anergy were being treated with corticosteroids, 44% with methotrexate, and 33% with biological therapy. Treatment with moderate to high dose prednisone and biological therapy were independently associated as risk factors for presenting with anergy, OR 1.044 [95% CI, 1.008-1.080 P<.05] and OR 1.096 [95% CI, 1.016-1.182, P<.05], respectively. The overall positivity for tuberculin was 13%. Symptoms associated with disease activation were present in 38% of these. All cases (n= 1) of confirmed active tuberculosis were excluded.

Conclusions:

The high prevalence of cutaneous anergy in patients with RA in the present study, and the evidence presented here, supports the recommendation of a second diagnostic test (tuberculin booster or Interferon-Gamma Release Assays) for the diagnosis of latent TB in patients with RA on immunosuppressive therapy.

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