br Introduction The use of tumor necrosis

Introduction The use of tumor necrosis factor-α (TNF-α) antagonists in psoriatic patients has become more common in recent years. However, patients treated with TNF-α antagonists are at increased risk of latent tuberculosis infection (LTBI) reactivation; therefore, screening for LTBI prior to initiating TNF-α antagonist therapy is important. The tuberculin skin test (TST) is considered one of the standard methods of screening for TB infection. However, TST has some disadvantages. For example, false-positive results may occur in patients previously vaccinated with bacille Calmette-Guérin (BCG), which may limit its usefulness in high BCG-vaccinated populations. In addition, TST is not specific for Mycobacterium tuberculosis infection, and cross reactivity with environmental mycobacteria may occur. TST may also overestimate LTBI risk in psoriatic patients because the enhanced inflammatory process may cause koebnerization, which interferes with the evaluation of TST. Recently, whole-blood interferon-γ release assays (IGRAs) were introduced for the diagnosis of LTBI, including the QuantiFERON-TB Gold In-Tube test (QFT-GIT; Cellestis Limited, Carnegie, Victoria, Australia) and T-SPOT TB test (Oxford Immunotec, Oxford, UK). In cox 2 inhibitors to TST, IGRA is more specific for screening LTBI and is not affected by BCG vaccination. Therefore, IGRA is considered superior to TST for detecting LTBI in countries with an intermediate to high burden of TB as well as in countries with high BCG vaccination rates.
Materials and methods
Results
Discussion In recent years, TNF-α antagonists have become increasingly popular in the treatment of psoriasis and other rheumatoid diseases although the increased risk of LTBI reactivation has also now become an important issue in clinical practice. Taiwan is a country with an intermediate burden of TB with an annual incidence of 57/100,000 and mortality rate of 2.8/100,000. According to Matulis et al, those living in countries with a high prevalence of TB had a higher risk of developing LTBI. Therefore, screening for LTBI before and during the treatment with TNF-α antagonists is essential to prevent adverse effects of the medication and control an infectious disease. According to previous studies, the mechanisms by which TNF-α antagonists interfere with anti-TB immunity may be related to blocking TNF-mediated immune responses, inhibiting phagolysosomal maturation, inducing monocyte apoptosis, and reducing IFN-γ secretion by memory T cells. Among the TNF-α antagonists, patients treated with adalimumab had a greater risk of developing TB than those treated with etanercept. The median time of developing TB in patients treated with adalimumab and etanercept were 3–8 months and 11.2 months, respectively. Therefore, the recommended interval of screening for LTBI during the TNF-α antagonist therapy was at least 12 months. TB screening is recommended prior to initiating TNF-α antagonist therapy and at yearly intervals, thereafter. TB infection screening should include detailed medical history, chest X-ray, and either TST or IGRA tests. The medical history should include TB infection risk factors such as residence in a country with a burden of TB, travel to endemic areas, substance abuse, or health care employment that may result in contact with patients who have TB. In addition, it is necessary to ascertain whether the patient had any symptoms related to TB infection, including cough, loss of body weight, night sweats, and fever. Currently, TST and IGRA are the two available methods for detection of LTBI. Although some studies showed consistent results between the two tests, systemic review and meta-analysis showed that the specificity of IGRAs was superior to TST. The odds ratio for positive TST results in patients who received BCG vaccination varied from three to 25, whereas IGRA was not influenced by BCG vaccination. Taiwan launched the neonatal BCG vaccination program in 1965, and the coverage rate was above 97% after 2001. The coverage rate (95%) of BCG vaccinations in our series was similar to the nationwide data; therefore, IGRA is more specific and suitable for detection of LTBI in this study.