High rates of tuberculin skin test positivity due to methotrexate therapy: False positive results?

Prevalence of positive tuberculin skin test in a Brazilian sample of rheumatoid arthritis and spondylarthritis patients

OBJECTIVE

Patients with rheumatic diseases have an increased risk of infections, especially tuberculosis. In this study, we aimed to recognize the positivity rate of tuberculosis skin test in patients with rheumatoid arthritis and spondyloarthritis and the characteristics of the patients with positive results.

METHODS

Retrospective study of tuberculosis skin test results in patients followed from 2004 to 2021 in a single rheumatology unit. Data related to clinical and epidemiological features, along with treatment information referring to the period in which the tuberculosis skin test was performed, were collected from patients' charts.

RESULTS

A total of 723 tests were identified (448 tests in 269 rheumatoid arthritis patients and 275 in 174 spondyloarthritis patients). In the rheumatoid arthritis sample, 31/275 (11.5%) individuals had positive tests, and in the spondyloarthritis, 38/174 (21.8%) had positive tests. In the rheumatoid arthritis sample, patients with positive tuberculosis skin tests used a higher dose of methotrexate than those with negative results (median of 25 mg/week versus median of 20 mg/week respectively; p=0.02). In the spondyloarthritis sample, tuberculosis skin test positivity was associated with alcohol ingestion (13.1% versus 2.9% in users and non-users respectively; p=0.02) and sulfasalazine use (15.7% of positivity in users versus 5% in non-users; p=0.01).

CONCLUSION

The tuberculosis skin test-positive prevalence in rheumatoid arthritis was lower than in the spondyloarthritis sample. Patients with rheumatoid arthritis using a higher dosage of methotrexate or with spondyloarthritis using sulfasalazine had more frequency of tuberculosis skin test positivity and should be carefully followed by the attending physician in order to avoid the appearance of full-blown tuberculosis.

Latent Tuberculosis in Psoriasis Patients on Biologic Therapies: Real-World Data from a Care Center in Romania

Background and Objectives: Psoriasis is a chronic and inflammatory condition that has a huge impact on the patient's quality of life. Biological treatment improved psoriasis therapy, with impressive results seen in the evolution of the disease and the patient's quality of life. However, the risk of mycobacterium tuberculosis (MTB) infection reactivation is well-known to biological therapy, which raises problems especially in an endemic country. Materials and Methods: In this study, we followed moderate to severe psoriasis patients who had latent tuberculosis infection (LTBI) following treatment with a biological therapy approved in Romania. Results: The patients were evaluated at baseline and then followed-up with Mantoux tests and chest X-rays every year, resulting in 54 patients being diagnosed with LTBI. At the initial evaluation, 30 patients with LTBI were identified, and 24 more were identified during biological therapy. These patients were given prophylactic treatment. Out of the 97 participants in this retrospective study, 25 required association of methotrexate (MTX) alongside biological therapy. We compared the prevalence of positive Mantoux tests in patients with combined therapy with that of patients only on biological treatment, and the results were higher in the combined therapy group. Conclusion: All the patients in the study were vaccinated against tuberculosis (TB) after birth, and none were diagnosed with active tuberculosis (aTB) before or after the start of therapy according to the pulmonologist.

Systematic literature review informing the 2022 EULAR recommendations for screening and prophylaxis of chronic and opportunistic infections in adults with autoimmune inflammatory rheumatic diseases

OBJECTIVE

To conduct a systematic literature review (SLR) on the screening and prophylaxis of opportunistic and chronic infections in autoimmune inflammatory rheumatic diseases (AIIRD).

METHODS

SLR (inception-12/2021) based on the following search domains: (1) infectious agents, (2) AIIRD, (3) immunosuppressives/immunomodulators used in rheumatology, (4) screening terms and (5) prophylaxis terms. Articles were retrieved having the terms from (1) AND (2) AND (3) plus terms from (4) OR(5). Databases searched: PubMed, Embase and Cochrane Library.

EXCLUSION CRITERIA

studies on postoperative infections, paediatric AIIRD, COVID-19, vaccinations and non-Εnglish literature. Study quality was assessed with Newcastle-Ottawa scale for non-randomised controlled trials (RCTs), RoB-Cochrane for RCTs, AMSTAR2 for SLRs.

RESULTS

From 5641 studies were retrieved, 568 full-text articles were assessed for eligibility, with 194 articles finally included. For tuberculosis, tuberculin skin test (TST) is affected by treatment with glucocorticoids and conventional synthetic disease modifying anti-rheumatic drugs (DMARDs) and its performance is inferior to interferon gamma release assay (IGRA). Agreement between TST and IGRA is moderate to low. For hepatitis B virus (HBV): risk of reactivation is increased in patients positive for hepatitis B surface antigen. Anti-HBcore positive patients are at low risk for reactivation but should be monitored periodically with liver function tests and/or HBV-viral load. Risk for Hepatitis C reactivation is existing but low in patients treated with biological DMARDs. For Pneumocystis jirovecii, prophylaxis treatment should be considered in patients treated with prednisolone ≥15-30 mg/day for >2-4 weeks.

CONCLUSIONS

Different screening and prophylaxis approaches are described in the literature, partly determined by individual patient and disease characteristics.

Tuberculin test versus interferon gamma release assay in pregnant women with household contacts of tuberculosis patients

Background

Pregnant women who live in tuberculosis (TB)-affected households are more likely to develop latent TB infection (LTBI), which often escapes treatment. This study aims to determine if Interferon-gamma release (IGRA) is reliable in screening for LTBI in pregnant women, compare to the tuberculin skin test (TST).

Methods

It was a cross-sectional study that involved 60 pregnant women with TB contact history as a proxy for LTBI and 30 pregnant women without contact history. Latent TB was detected using the TST 5 tuberculin units and IGRA using the QuantiFERON Gold Plus TB Test kit (QFT-Plus). The sensitivity and specificity of the two diagnostic methods and the agreement between them were estimated using SPSS version 20.0.

Results

The sensitivity 95% (95% confidence interval [CI]: 86.08%-98.96%) and specificity 26.7% (95% CI: 12.28%-45.89%) of TST were compared to that of the IGRA with 60% (95% CI: 46.54%-72.44%) and 73.3% (95% CI: 54.11%-87.72%) sensitivity and specificity, respectively in detecting LTBI in pregnancy. Although there was a significant difference (P < 0.05) between TST and IGRA, the agreement was fair (kappa 0.39; 95% CI: 0.24-0.45).

Conclusion

TST assay is more sensitive than IGRA; however, the specificity of IGRA was superior to the TST method. In this study, a fair agreement of TST and IGRA was observed for detecting latent TB infection in pregnant women with household contact with TB patients.

Clinical and epidemiological correlates of low IFN-gamma responses in mitogen tube of QuantiFERON assay in tuberculosis infection screening during the COVID-19 pandemic: A population-based marker of COVID-19 mortality?

Background

The clinical and epidemiological implications of abnormal immune responses in COVID-19 for latent tuberculosis infection (LTBI) screening are unclear.

Methods

We reviewed QuantiFERON TB Gold Plus (QFT-Plus) results (36,709 patients) from July 2016 until October 2021 in Asturias (Spain). We also studied a cohort of ninety hospitalized patients with suspected/confirmed COVID-19 pneumonia and a group of elderly hospitalized patients with COVID-19 who underwent serial QFT-Plus and immune profiling testing.

Results

The indeterminate QFT-Plus results rate went from 1.4% (July 2016 to November 2019) to 4.2% during the COVID-19 pandemic. The evolution of the number of cases with low/very low interferon-gamma (IFN-gamma) response in the mitogen tube paralleled the disease activity and number of deaths during the pandemic waves in our region (from March 2020 to October 2021). The percentages of positive QFT-plus patients did not significantly change before and during the pandemic (13.9% vs. 12.2%). Forty-nine patients from the suspected/confirmed COVID-19 pneumonia cohort (54.4%) had low/very low IFN-gamma response to mitogen, 22 of them (24.4%) had severe and critical pneumonia. None received immunosuppressants prior to testing. Abnormal radiological findings (P = 0.01) but not COVID-19 severity was associated with low mitogen response. Immune profiling showed a reduction of CD8 + T cells and a direct correlation between the number of EMRA CD8 + T-cells and IFN-gamma response to mitogen (P = 0.03).

Conclusion

Low IFN-gamma responses in mitogen tube of QFT-Plus often occur in COVID-19 pneumonia, which is associated with a low number of an effector CD8 + T-cell subset and does not seem to affect LTBI screening; however, this abnormality seems to parallel the dynamics of COVID-19 at the population level and its mortality.

Usefulness of screening tests for diagnosis of latent tuberculosis infection in children

BACKGROUND

The aim of this study is to provide a basis for the development of appropriate screening strategies and evaluate the indications of the interferon-gamma release assay (IGRA) in Bacillus Calmette-Guérin (BCG)-vaccinated children.

METHODS

Children who were examined with both IGRA (QuantiFERON®-TB Gold Plus) and tuberculin skin test (TST) for tuberculosis infection were included in the study. Underlying medical conditions of the patients were recorded. Cohen's κ was run to determine if there was an agreement between TST and IGRA.

RESULTS

A total of 220 patients with a mean age of 11.05 ± 4.43 years (2.5-18 years) were analyzed. Ninety-nine patients were immunocompromised and 121 patients were immunocompetent. TSTs and IGRA showed none to the slight agreement in both of the immunocompromised and immunocompetent patients. In the immunocompromised group, 43/99 (43.4%) and the immunocompetent group 35/121 (28.9%) of the tests did not show any correlation.

CONCLUSION

In a high-risk setting where the BCG vaccine is mandatory, it may be beneficial to use IGRA primarily in immunocompetent patients. In immunocompromised patients, the use of both the TST and IGRA could increase the efficacy of screening for latent tuberculosis infection.

TST conversions and systemic interferon-gamma increase after methotrexate introduction in psoriasis patients

Background

Tuberculosis screening in psoriasis patients is complex due to the immunological alterations associated with psoriasis, the presence of comorbidities, and the effect of immunosuppressive treatment. However, it is not established whether the results of screening tests are affected by these factors in psoriasis patients.

Objectives

To determine whether there is a change in the results of the tuberculin skin test (TST) or the interferon-gamma release assay (IGRA) in psoriasis patients living in tuberculosis (TB)-endemic area after 12 weeks of methotrexate (MTX) treatment and to investigate the association of the test results with clinical and inflammatory markers.

Methods

Forty-five patients were selected for a prospective single-arm self-controlled study and followed for at least 18 months. The TST, IGRA, Psoriasis Area and Severity Index (PASI), and inflammatory factors (erythrocyte sedimentation rate (ESR), C-reactive protein, interferon-gamma (IFN-γ), and tumor necrosis factor-alpha levels), were determined before and after 12 weeks of oral 15 mg per week MTX administration and compared. The associations between the IGRA and TST results were verified before and after treatment according to inflammatory factors and clinical characteristics (age, blood glucose, weight, body mass index, disease duration, and PASI).

Results

We collected data on 25 patients who completed the full course of therapy and the follow-up. None of the patients developed TB. TST positivity was significantly elevated at week 12 (25% baseline vs 44% at week 12, P < 0.037). Three IGRAs followed the TST conversions. There was no difference between TST and IGRA pre- or posttreatment. Serum IFN-γ increased significantly in week 12 (15.95 pg/ml baseline vs 18.82 pg/ml at week 12, P < 0.005) and tended to be higher among TST-positive patients (P = 0.072). The baseline IGRA was associated with a higher ESR (P = 0.038). None of the test results were associated with clinical characteristics.

Conclusions

In addition to the classic booster effect, TST conversions in patients using MTX can occur due to an increase in IFN-γ. However, it is not possible to exclude true TST conversions. Therefore, other diagnostic methods, like IGRA or chest tomography, should be used when the TST has intermediate results.

Determination of tuberculin skin test for isoniazid prophylaxis in BCG vaccinated children who are using anti-TNF agents for rheumatologic diseases

OBJECTIVE

The use of tumor necrosis factor inhibitors (anti-TNF) has a risk of activating latent tuberculosis infection (LTBI). This study was performed to investigate LTBI according to tuberculin skin test (TST) size and to determine the frequency of tuberculosis (TB) in bacillus Calmette-Guerin (BCG)-vaccinated children receiving anti-TNF treatment for rheumatological disease.

MATERIALS AND METHODS

The study consisted of 559 children. Information on demographics, anti-TNF agents, TST size, and isoniazid (INH) prophylaxis was recorded. Patients (n = 254) with TST size ≥5 mm were divided into three groups according to TST size and INH prophylaxis: group 1, TST size 5 to 9 mm and no INH prophylaxis; group 2, TST size 5 to 9 mm with INH prophylaxis; and group 3, TST size ≥10 mm with INH prophylaxis.

RESULTS

The 559 patients comprised 314 (56.3%) females and 245 (43.6%) males; they had a mean age of 13.1 ± 4.1 years. The mean TST size in all patients was 4.2 ± 4.7 mm. Group 1 consisted of 76 (29.9%) patients, group 2 consisted of 88 (34.6%) patients, and group 3 consisted of 90 (35.4%) patients. The mean TST sizes for the three groups were 6.8 ± 3.1 mm, 7.2 ± 3.2 mm, and 13.9 ± 2.8 mm, respectively. New TB was diagnosed in only two (0.35%) patients. Both of them were in group 3.

CONCLUSIONS

A TST size of ≥10 mm in BCG-vaccinated children receiving anti-TNF treatment may distinguish children at high risk for reactivation of LTBI.

Borderline-Positive Quantiferon in Children

We systematically retested children with borderline-positive quantiferon (0.35-0.99 IU/mL) during the period 2015-2019. Among 647 tests, 27 (4%) were positive (>0.35 IU/mL). Borderline-positive quantiferon accounted for 10 of 27 (37%) positive tests. When retested, 9 of 10 (90%) were negative. Children younger than 5 years had negative tuberculin skin tests. Thus, we found high test variability in the borderline range and, in some children, high suspicion of false positive tests.

Risk of tuberculosis reactivation associated with traditional disease modifying anti-rheumatic drugs and non-anti-tumor necrosis factor biologics in patients with rheumatic disorders and suggestion for clinical practice

INTRODUCTION

Two classes of biologics, anti-tumor necrosis factor (TNF) and non-anti-TNF targeted, are currently available for the treatment of rheumatic diseases.

AREAS COVERED

Discussion on the need for LTBI diagnosis in rheumatic patients treated csDMARDs and non-anti-TNFs through a review of the literature. The literature, updated to 15 April 2019, on tuberculosis (TB) reactivation risk in patients exposed to conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) and non-anti-TNF biologics was reviewed.

EXPERT OPINION

An increased risk of TB reactivation in patients receiving csDMARDs (except sulphasalazine) resulted, while a review of clinical trials, and Periodic Safety Update Reports from pharmaceutical Companies evidenced a very low or absent risk for non-anti-TNF biologics. Hence, a contradiction emerges considering that latent TB infection (LTBI) screening is recommended for non-anti-TNF candidates but not for csDMARDs. Concerning the low TB incidence countries, several actions could be undertaken, including to screen all patients independently on the treatment, to omit the procedure in non-anti-TNF candidates, or to perform the LTBI investigations only in high-risk patients. According to WHO guidelines, LTBI screening in low TB risk countries seems unnecessary, except in high TB risk subjects.