The Significance of Sensitive Interferon Gamma Release Assays for Diagnosis of Latent Tuberculosis Infection in Patients Receiving Tumor Necrosis Factor-α Antagonist Therapy

Resuming anti-TNF therapy after development of miliary tuberculosis in Behcet's disease-related uveitis: a case report

PURPOSE

There is no consensus concerning restarting anti-tumour necrosis factor (TNF)-α therapy for uveitis after treatment for active tuberculosis (TB). We report a case of Behcet disease (BD) in which treatment with TNF inhibitor was successfully resumed after treatment for miliary TB.

CASE REPORT

A 48-year-old Japanese male was treated for uveitis of unknown aetiology in the left eye at a general ophthalmology clinic. He was referred to Department of Ophthalmology, Tokyo Medical University Hospital because of macula oedema (ME) not responding to prednisolone (PSL) 20 mg. BD was diagnosed based on fluorescein angiographic findings of diffuse retinal vasculitis characteristic of BD, recurrent oral aphthous ulcer, erythema nodosum-like rash in his legs, and HLA-A26 positivity. After a screening test, adalimumab (ADA) was started as steroid-sparing therapy. Eight months after starting ADA, the patient was diagnosed with miliary TB. ADA and PSL were discontinued immediately due to TB. Anti-TB treatment was completed after 6 months based on clinical improvement, although T-SPOT.TB was still positive. Infliximab with isoniazid was started due to relapse of ME, worsened vitreous haze, and worsened visual acuity in his left eye. Subsequently, his ocular symptoms subsided and there was no relapse of TB.

CONCLUSION

This case suggests that in patients with BD who have discontinued anti-TNF therapy due to miliary TB, restarting anti-TNF therapy may be a therapeutic option after TB has been treated appropriately with careful monitoring for relapse.

Prevalence and management of tuberculosis infection in Apulian rheumatologic patients treated with biologics: An observational cohort 10-year study from the BIOPURE registry

INTRODUCTION

The objective of this study was to assess the 10-year prevalence of latent tuberculosis infection (LTBI) among Apulian patients with rheumatic diseases (RDs). Secondary endpoint was to record new cases of active TB disease and LTBI among patients treated with biologic disease-modifying antirheumatic drugs (bDMARDs).

METHODS

We analysed the results from the patients included in the BIOPURE registry from 2009 to 2018, who underwent QuantiFERON-TB Gold In-tube (QFT-GIT) test as screening before bDMARDs treatment. Demographic and clinical data were recorded at the time of the first QFT-GIT test. Administration of preventive therapy and bDMARD treatments were recorded for patients with positive QFT-GIT test. All new tuberculosis infections were recorded during the follow-up.

RESULTS

The final study population included 3028 patients (855 rheumatoid arthritis, 1001 psoriatic arthritis, 833 spondyloarthritis, 130 connective tissue diseases, 33 systemic vasculitis and 176 other inflammatory rheumatic conditions), more frequently female (67.2%), with a mean age of 52 ± 18 years. Patients with QFT-GIT-positive test were elderly people, predominantly male with higher prevalence of diabetes as comorbidity. The 10-year prevalence of LTBI was 10.8%. Of note, no cases of TB reactivation were recorded in patients who completed preventive therapy treatment. Three thousand and sixteen patients were followed over time (42.6 ± 30 months), and five (.2%) developed active TB, which corresponds to .47 cases per 1000 person-years.

CONCLUSIONS

In the 10-year observation, the use of bDMARDs seems to be safe in rheumatologic patients with positive QFT-GIT test treated according to current recommendations. Nevertheless, cases of primary TB disease did occur during treatment with biologicals.

Regional risk of tuberculosis and viral hepatitis with tumor necrosis factor-alpha inhibitor treatment: A systematic review

Background: TNFα inhibitors are regularly used to treat autoimmune diseases. Tuberculosis (TB) and viral hepatitis B are considered potential infectious complications, and screening and surveillance are therefore recommended. Current guidelines do not take into account regional differences in endemicity of these infections. Methods: A systematic literature review of TB and viral hepatitis in patients receiving TNFα-inhibitors was performed, searching in PubMed, Embase, MEDLINE and Web of Science databases. Studies were selected against predefined eligibility criteria and assessed using the Newcastle-Ottawa scale. The number of TB and viral hepatitis cases/1,000 TNFα-inhibitor patients were evaluated, and regional variation compared. Results: 105 observational studies involving over 140,000 patients were included. Overall, 1% of patients developed TB or viral hepatitis B. TB cases/1,000 TNFα-inhibitor patients were 4-fold higher in Asia, Africa, and South America than in Europe, North America, and Australasia where only 0%-0.4% of patients developed TB. Hepatitis B cases/1,000 patients were over 15-fold higher in countries with high prevalence (China, Taiwan, South Korea, Thailand) compared with low prevalence (p < 0.00001) where only 0.4% of patients developed hepatitis B. Only three of 143 patients developed viral hepatitis C, and there was insufficient data to allow regional sub-analysis. Conclusion: TB and viral hepatitis B infections in patients treated with TNFα inhibitors are largely confined to countries with high prevalence of these infections. As only 1/2,500 patients in low prevalence countries treated with TNFα inhibitors develop TB or viral hepatitis B, we suggest an individualized, risk-based approach, rather than universal screening for all patients.

Comparison of Interferon-Gamma Release Assay and Tuberculin Skin Test for the Screening of Latent Tuberculosis in Inflammatory Bowel Disease Patients: Indian Scenario

Background

In a country like India, where the prevalence of tuberculosis is very high, the role of screening tools for detection of latent tuberculosis infection (LTBI) like TST and IGRA is still unclear, especially in inflammatory bowel disease (IBD) patients. Our study is aimed at comparing the interferon-gamma release assay (IGRA) and tuberculin skin test (TST) to determine the prevalence of LTBI in IBD patients in the Indian subset of the population.

Methods

It was a prospective observational analysis. A total of 257 participants were included in the study. Both TST and IGRA were performed in consecutive patients diagnosed with IBD (131 patients) and in 126 healthy individuals. Both tests were performed on the same day. LTBI diagnosis was considered if any one of TST or IGRA was found to be positive.

Results

Out of 131 IBD patients, 121 patients had ulcerative colitis and 10 patients had Crohn's disease. 29% of the IBD patients and 22% of the control subjects had LTBI. The study demonstrated concordance between TST and IGRA. Agreement test kappa value for IBD patients was 0.656 (CI 0.50-0.81), with a p value of <0.001, suggestive of a fair agreement. Mean IFN-γ release was lower in the immunosuppressed group as compared to non-immunosuppressed individuals (0.26 ± 0.17 vs. 0.45 ± 0.07, p = 0.02). Cohen's kappa coefficient values in IBD cases and control subjects were 0.66 and 0.79, respectively. TST was found to be negatively correlated to BMI.

Conclusion

Agreement between TST and IGRA was fair in IBD patients. For LTBI screening in IBD patients, TST and IGRA are complementary methods.

The necessity, efficacy and safety of biologics in juvenile idiopathic arthritis

OBJECTIVE:

Juvenile idiopathic arthritis (JIA) is the most common cause of chronic arthritis in children. Biologics have changed the faith of children with rheumatic diseases. The main objective of this study was to demonstrate the rate of usage, efficacy and safety of biologics in JIA subtypes.

METHODS:

This retrospective observational cohort study was conducted between May 2010 and September 2017. All children with the diagnosis of JIA and children under a biological agent treatment were recorded into the local registry system. Age, gender, JIA subtype, medications used, the clinical status of the patient, tuberculosis screening results, and side effects observed under biologics were retrieved from the registry.

RESULTS:

There were 405 patients with the diagnosis of JIA in the cohort. Biologics were used in 123 (30.3%) JIA patients. Subtype frequencies of JIA patients were as follows: persistent oligoarticular JIA (33.6%), enthesitis-related arthritis (29.2%), systemic JIA (13%), rheumatoid factor (RF)-negative polyarticular JIA (13%), extended oligoarticular JIA (4.2%), RF-positive polyarticular JIA (3.4%), psoriatic arthritis (1.8%) and unclassified arthritis (1.8%). The rate of biologic use was high in extended oligoarticular JIA (64.7% of the cases), RF-positive polyarticular JIA (57.1%), psoriatic arthritis (57.1%), RF-negative polyarticular JIA (41.5%), and in systemic JIA (39.6%). Enthesitis-related arthritis (27.1%), persistent oligoarticular JIA (17.6%) and unclassified arthritis (16.6%) patients were the cases that needed a biologic agent in the last order. At the last control, 78.9% of the cases were in remission, while 21.1% of them were active despite biologic treatment. Isoniazid prophylaxis was used in 30.8% of the patients. None of the patients developed active tuberculosis infection under prophylaxis. Adverse events were observed in 18.6% of patients under biologics as recurrent uncomplicated upper respiratory tract infections being the most common.

CONCLUSION:

Biologics are safe and effective treatment options in children with JIA. Most of the JIA patients with polyarticular involvement require biologics earlier in the disease course. The risk of tuberculosis infection seems not to be increased after appropriate screening and prophylaxis.

Conversion and Reversion Rates of Tuberculosis Screening Assays in Patients With Rheumatic Diseases and Negative Baseline Screening Under Long-Term Biologic Treatment

Background:

To determine the conversion and reversion rates of tuberculosis (TB) screening tests (Tuberculin Skin Test-TST, Interferon Gamma Release Assay-IGRA: T-SPOT.TB) during biologic treatment in patients with rheumatic diseases and negative baseline screening.

Methods:

This was a long-term, longitudinal cohort study of 50 patients with rheumatic diseases and negative baseline TB screening (TST: < 5 mm, negative T-SPOT.TB) treated with tumor necrosis factor inhibitors (TNFi) or other non-TNFi biologics. Patients were rescreened at a mean time of 1.4 (first rescreening) and 6.9 (second rescreening) years from baseline, with both assays. The conversion (negative to positive) and reversion (positive to negative) rate was calculated for each TB screening test.

Results:

Fifty patients (mean age = 60 years) with various rheumatic diseases (rheumatoid arthritis: n = 24, spondyloarthropathies: n = 23, other: n = 3) were enrolled. During the first phase (baseline to first rescreening), all patients were treated with TNFi while during the second phase (first to second rescreening), TNFi (54%) and non-TNFi (46%) were used. Fifteen patients (30%) displayed conversion of at least 1 screening assay during follow-up (10 at the first and 5 at the second rescreening). This conversion rate was higher with TST (n = 11, 22% or 3.47/100 patient-years) compared to T-SPOT.TB (n = 4, 8% or 1.74/100 patient-years). Among the 10 converters at the first rescreening, 5 received isoniazid (INH) preventive therapy and 5 did not; an equal number of patients (3/5, 60%) reverted to negative with or without INH therapy. None of the patients developed active TB during follow-up (6.9 ± 1.0 years).

Conclusions:

Approximately one-third of patients with rheumatic diseases and negative baseline TB screening developed conversion of at least 1 screening test during long-term biologic treatment. This occurred most often with TST and was usually a transient event. These findings do not support routine serial TB retesting in biologic-treated patients with rheumatic diseases in the absence of TB risk factors.

The T-SPOT.TB assay used for screening and monitoring of latent tuberculosis infection in patients with Behçet's disease pre- and post-anti-TNF treatment: A retrospective study

BACKGROUND

Patients undergoing anti-tumor necrosis factor (TNF) treatment are more susceptible to latent tuberculosis infection (LTBI). The aim of the current study was to determine the rate of active tuberculosis (TB) in patients with Behçet's disease (BD) pre- and post-anti-TNF treatment and to evaluate the long-term efficacy of LTBI screening as primary prophylaxis in China.

METHODS

This retrospective study included BD patients eligible for anti-TNF therapy at a single institution in Fudan University, China. On the basis of the results of T-SPOT.TB assay, chest radiograph, and history of exposure to TB, patients were screened and regularly followed up at 3-months interval.

RESULTS

Eighty-nine BD patients with mean disease duration of 87.5 ± 86.1 months were included. Their median duration of anti-TNF therapy was 10.6 months; 51 patients were treated with Infliximab, 38 with Etanercept, and four with Adalimumab. While 84 patients received a consecutive single anti-TNF drug therapy, five patients switched to a second drug. Twelve patients demonstrated positive results in LTBI screening: three had history of TB exposure and nine were solely T-SPOT.TB-positive patients. Before anti-TNF treatment, LTBI treatment was initiated in 11 patients, and one patient refused treatment. With a median follow-up period of 27.9 months, we observed only one case (1.1%) of intestinal TB during Infliximab treatment.

CONCLUSION

Regardless of anti-TNF treatment, long-term screening via T-SPOT.TB assay might represent a more sensitive approach to identify BD patients with LTBI. As a secondary prophylaxis, the LTBI treatment is effective in a country with high risk of TB.

Diagnostic value of the interferon-γ release assay for tuberculosis infection in patients with Behçet's disease

BACKGROUND

To investigate the diagnostic value of the interferon-γ release assay (IGRA) for detecting tuberculosis (TB) infection in patients with Behçet's disease (BD).

METHODS

We retrospective analyzed the data collected from 173 BD patients hospitalized between 2010 and 2015. Ninety-nine healthy volunteers were enrolled as a control group. IGRA was performed using T-SPOT.TB. The diagnosis of active TB (ATB) was based on clinical, radiological, microbiological, histopathological information and the response to anti-TB therapy. Latent TB (LTB) infection was defined as asymptomatic patients with positive T-SPOT.TB.

RESULTS

TB infection was documented in 59 BD patients (34.1%). The sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio and negative likelihood ratio of T-SPOT.TB for the diagnosis of ATB were 88.9%, 74.8%, 29.1%, 98.3%, 3.53 and 0.15, respectively. The receiver-operating-characteristic curve demonstrated that spot-forming cells (SFCs) of 70/106 PBMC was the optimal cutoff for diagnosing ATB, with an area under the curve of 0.891. Furthermore, the median SFCs in ATB group was significantly higher than those in LTB infection (466/106 PBMC vs. 68/106 PBMC, p = 0.007) or previous TB infection (466/106 PBMC vs. 96/106 PBMC, p = 0.018). A significant discrepancy between T-SPOT.TB and tuberculin skin test was noted (kappa coefficient = 0.391, p = 0.002).

CONCLUSIONS

T-SPOT.TB, an IGRA, may assist in the diagnosis of ATB in BD patients, and the higher SFCs suggest ATB in BD patients.

Two interferon gamma release assays for predicting active tuberculosis: the UK PREDICT TB prognostic test study

BACKGROUND

Despite a recent decline in the annual incidence of tuberculosis (TB) in the UK, rates remain higher than in most Western European countries. The detection and treatment of latent TB infection (LTBI) is an essential component of the UK TB control programme.

OBJECTIVES

To assess the prognostic value and cost-effectiveness of the current two interferon gamma release assays (IGRAs) compared with the standard tuberculin skin test (TST) for predicting active TB among untreated individuals at increased risk of TB: (1) contacts of active TB cases and (2) new entrants to the UK from high-TB-burden countries.

DESIGN

A prospective cohort study and economic analysis.

PARTICIPANTS AND SETTING

Participants were recruited in TB clinics, general practices and community settings. Contacts of active TB cases and migrants who were born in high-TB-burden countries arriving in the UK were eligible to take part if they were aged ≥ 16 years.

MAIN OUTCOME MEASURES

Outcomes include incidence rate ratios comparing the incidence of active TB in those participants with a positive test result and those with a negative test result for each assay, and combination of tests and the cost per quality-adjusted life-year (QALY) for each screening strategy.

RESULTS

A total of 10,045 participants were recruited between May 2010 and July 2015. Among 9610 evaluable participants, 97 (1.0%) developed active TB. For the primary analysis, all test data were available for 6380 participants, with 77 participants developing active TB. A positive result for TST^a (positive if induration is ≥ 5 mm) was a significantly poorer predictor of progression to active TB than a positive result for any of the other tests. Compared with TST^b [positive if induration is ≥ 6 mm without prior bacillus Calmette-Guérin (BCG) alone, T-SPOT^®.TB (Oxford Immunotec Ltd, Oxford, UK), TST^a + T-SPOT.TB, TST^a + IGRA and the three combination strategies including TST^b were significantly superior predictors of progression. Compared with the T-SPOT.TB test alone, TST^a + T-SPOT.TB, TST^b + QuantiFERON^® TB Gold In-Tube (QFT-GIT; QIAGEN GmbH, Hilden, Germany) and TST^b + IGRA were significantly superior predictors of progression and, compared with QFT-GIT alone, T-SPOT.TB, TST^a + T-SPOT.TB, TST^a + QFT-GIT, TST^a + IGRA, TST^b + T-SPOT.TB, TST^b + QFT-GIT and TST^b + IGRA were significantly superior predictors of progression. When evaluating the negative predictive performance of tests and strategies, negative results for TST^a + QFT-GIT were significantly poorer predictors of non-progression than negative results for TST^a, T-SPOT.TB and TST^a + IGRA. The most cost-effective LTBI testing strategies are the dual-testing strategies. The cost and QALY differences between the LTBI testing strategies were small; in particular, QFT-GIT, TST^b + T-SPOT.TB and TST^b + QFT-GIT had very similar incremental net benefit estimates.

CONCLUSION

This study found modest differences between tests, or combinations of tests, in identifying individuals who would go on to develop active TB. However, a two-step approach that combined TST^b with an IGRA was the most cost-effective testing option.

IMPLICATIONS FOR PRACTICE AND FUTURE RESEARCH

The two-step TST^b strategy, which stratified the TST by prior BCG vaccination followed by an IGRA, was the most cost-effective approach. The limited ability of current tests to predict who will progress limits the clinical utility of tests. The implications of these results for the NHS England/Public Health England national TB screening programme for migrants should be investigated.

STUDY REGISTRATION

This study is registered as NCT01162265.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Comparative Evaluation of QuantiFERON-TB Gold In-Tube and QuantiFERON-TB Gold Plus in Diagnosis of Latent Tuberculosis Infection in Immunocompromised Patients

QuantiFERON-TB Gold Plus (QFT-Plus) is a new-generation QuantiFERON-TB Gold In-Tube (QFT-GIT) assay which has two antigen-coated tubes called TB1, which contains long peptides derived from ESAT-6 and CFP-10, and TB2, which contains the same components as TB1 and additional short peptides which potentially stimulate CD8⁺ T cells through the presentation of major histocompatibility complex class I. This is the first study to compare QFT-Plus and QFT-GIT for use in the diagnosis of latent tuberculosis infection (LTBI) among immunocompromised patients in the Republic of Korea. Among 317 consecutive patients who underwent screening for LTBI before solid organ or hematopoietic stem cell transplantation and tumor necrosis factor alpha inhibitor treatment, LTBI was identified in 92 (29.0%) and 88 (27.8%) patients by QFT-GIT and QFT-Plus, respectively. The rate of concordance between QFT-GIT and QFT-Plus was 93.7% (κ value, 0.860), and the indeterminate rate (3.2%) was similar between QFT-GIT and QFT-Plus. Of 20 (6.3%) samples with discordant results, 11 (55.0%) and 7 (35.0%) were positive by QFT-GIT alone and QFT-Plus alone, respectively, and 2 (15.0%) were indeterminate by each assay. The interferon gamma level in samples with discordant results ranged from 0.39 to 1.10 IU/ml, except for one sample, in which the gamma interferon level was 2.97 IU/ml only in TB2. Conclusively, there was a high degree of agreement between the results of QFT-GIT and QFT-Plus for the screening of immunocompromised patients for LTBI. The reactivity in TB2 contributed substantially to the difference between QFT-GIT and QFT-Plus, particularly in solid organ transplant candidates. The significance of the discrete responses in TB1 and TB2 of QFT-Plus needs to be explored further by means of an immunological and clinical approach in different patient groups and clinical settings.

Challenges in screening for latent tuberculosis in inflammatory bowel disease prior to biologic treatment: a UK cohort study

OBJECTIVE

The aim of this study was to determine the occurrence of latent tuberculosis infections (LTBI) and active TB in a cohort of patients with inflammatory bowel disease (IBD) treated with biologics. We also examined the effects of immunosuppressive drugs on indeterminate interferon-gamma release assays (IGRA) in LTBI screening.

DESIGN

Retrospective study of patients treated with biologics between March 2007 and November 2015.

SETTING

St Mark's Hospital, North West London, UK.

PATIENTS

732 patients with IBD who were screened for LTBI using either tuberculin skin test or IGRA before starting a biologic treatment.

METHODS

Retrospective case note review of all patients with IBD who were screened for LTBI prior to initiating biologics. Patients who developed active TB were identified from the London TB register.

RESULTS

Of 732 patients with IBD, 31 (4.2%) were diagnosed with and treated for LTBI with no significant side effects. Six of 596 patients (1.0%) who received biologic treatment developed active TB. There was a higher proportion of indeterminate IGRA in the immunosuppressive medication group compared with the non-immunosuppressive group (33% (59/181) compared with 9% (6/66), p<0.001). The combination of steroids and thiopurines had the highest proportion of indeterminate IGRA (64%, 16/25). High and low doses of steroids were equally likely to result in an indeterminate IGRA result (67% (8/12) and 57% (4/7), respectively).

CONCLUSIONS

This study highlights the challenges of LTBI screening prior to commencing biologic therapy and demonstrates the risk of TB in patients who have been screened and who are receiving prolonged and continuing doses of antitumour necrosis factor.

Serial Tuberculosis Screening in Inflammatory Bowel Disease Patients Receiving Anti-TNFα Therapy

BACKGROUND AND AIMS

One of the adverse effects of the tumour necrosis factor alpha [[TNFα] monoclonal antibodies for the treatment of immune-mediated inflammatory diseases is a higher propensity for tuberculosis development. The aim of this study was to explore the utility and sensitivity of serial tuberculosis screening during anti-TNFα treatment.

METHODS

A cohort of 46 inflammatory bowel disease patients receiving infliximab was prospectively recruited and followed for 26 months. During this period of time, a tuberculosis skin test and two different interferon ϒ release assays [QFT-GIT and T-SPOT.TB] were applied at 4-6-month intervals.

RESULTS

Overall, 16 patients were diagnosed with latent tuberculosis infection after having at least one test conversion: 12 patients had a positive tuberculosis skin test, seven patients had a positive T-SPOT.TB, and two patients had a positive QFT-GIT. Active tuberculosis was excluded in all; 15 were treated with isoniazid. A comparison between tests showed a moderate accuracy [72% to 85%] but low kappa values [0.063 to 0.377]. Concerning association with demographic and clinical characteristics, test conversion was more common among the male gender and those with a longer disease duration.

CONCLUSIONS

Tuberculosis tests conversions were common in inflammatory bowel disease patients treated with infliximab alone or in association with immunomodulators. In these immunosuppressed individuals, the classical tuberculosis skin test seems to have a higher sensitivity than the modern tests based on the release of interferonϒ.

Use of IFN-γ and IP-10 detection in the diagnosis of latent tuberculosis infection in patients with inflammatory rheumatic diseases

OBJECTIVES

Biologic agents are used against rheumatic diseases, however, they increase the risk of developing severe infections and diseases such as tuberculosis. We aimed to determine the benefits of IP-10 detection to diagnose latent tuberculosis infection (LTBI) in patients with inflammatory rheumatic diseases on different immunosuppressive drug regimens, and compare these results with IFN-γ detection.

MATERIALS AND METHODS

We included 64 patients with inflammatory rheumatic diseases. We used QuantiFERON Gold In-Tube (QFN-G-IT) and T-SPOT.TB to detect IFN-γ production, and an in-house ELISA for IP-10 detection from the previous QFN-G-IT stimulated samples. We assessed the combined use of IFN-γ release assays (IGRAs) and IP-10 test, and analyzed the influence of immunotherapy on the tests performance.

RESULTS

We obtained 34.9% positive results by T-SPOT.TB, 25.0% by QFN-G-IT and 31.3% by IP-10 test. The combined use of IGRAs and IP-10 detection increased significantly the amount of positive results (p < 0.0001). Treatment intake had no significant effect on in vitro tests (p > 0.05).

CONCLUSIONS

IP-10 and IFN-γ detection is comparable and their combined use could increase the number of positive results in the diagnosis of LTBI in rheumatic patients. The tested assays were not influenced by rheumatoid immunosuppressive therapy. Thus, IP-10 could be of use in the development of new and improved LTBI diagnostic tools.

Elevated Neopterin Levels Are Associated with Increased Tuberculosis Risk in Rheumatoid Arthritis Patients with QuantiFERON Conversion during Biologic Therapy

QuantiFERON-TB-Gold (QFT-G) conversion is frequently observed in rheumatoid arthritis (RA) patients receiving biologic therapy. However, there have not been any known biomarkers available for detecting tuberculosis (TB) in QFT-G converters. We aimed to evaluate clinical utility of cytokines/chemokines for detecting TB in patients with QFT-G conversion. Among a total of 227 RA patients who underwent QFT-G assay, 187 QFT-G-negative patients received biologic therapy without isoniazid prophylaxis. QFT-G assay was repeated at week 52 of biologic therapy or at the time of TB diagnosis. Levels of cytokines/chemokines were determined by magnetic bead array or ELISA in QFT-G converters and 12 non-RA patients with TB (non-RA TB). QFT-G conversion was found in 54 (28.9%) of 187 baseline QFT-G-negative patients, of which 7 (13.0%) developed active TB during the one-year follow-up period. Among the examined cytokines/chemokines, non-stimulated and TB-antigen-stimulated neopterin levels were significantly higher in RA patients who developed TB (RA-TB) (median, 24.5pg/ml and 23053pg/ml, respectively) and non-RA TB patients (12.2pg/ml and 9633pg/ml, respectively) compared with QFT-G converters without TB (3.0pg/ml and 2720pg/ml, respectively, both p<0.001). Rising levels of neopterin relative to baseline (non-stimulated levels, 4.4pg/ml vs. 24.5pg/ml; TB-antigen-stimulated levels, 1801pg/ml vs. 23053pg/ml) were observed in QFT-G converters who developed TB. A high proportion (85.7%) of QFT-G converters with high plasma neopterin levels developed TB during the one-year follow-up period. In conclusion, RA patients with QFT-G conversion during the period of biologic therapy should be carefully monitored for elevation of neopterin levels, which is associated with TB risk in QFT-G converters, particularly in TB-endemic areas.

Concordance between the tuberculin skin test and interferon gamma release assay (IGRA) for diagnosing latent tuberculosis infection in patients with systemic lupus erythematosus and patient characteristics associated with an indeterminate IGRA

OBJECTIVE

We investigated the agreement between the tuberculin skin test (TST) and the QuantiFERON-TB gold (QFT-G) assay in the diagnosis of latent tuberculosis infection (LTBI) in patients with systemic lupus erythematosus (SLE). Furthermore, we evaluated the factors associated with indeterminate results in the QFT-G assay in patients with SLE.

METHODS

We enrolled 136 patients with SLE prospectively, and compared them to 66 patients with rheumatoid arthritis (RA). In addition to the TST, QFT-G assay, patients' medications, and Bacillus Calmette-Guérin (BCG) vaccination status were also investigated. A positive TST or QFT-G assay result without an active tuberculosis lesion on chest x-ray was considered to indicate a diagnosis of LTBI.

RESULTS

The prevalence of LTBI was 26.5% in patients with SLE and 30.3% in patients with RA. The agreement between the TST and QFT-G assay was fair in SLE patients, but poor in RA patients. BCG vaccination was one factor associated with discordance between TST and QFT-G. Older age and higher SLE Disease Activity Index (SLEDAI) score were associated with a negative TST/positive QFT-G result in patients with SLE. Higher SLEDAI score and increased glucocorticoid dose were associated with an indeterminate result in the QFT-G assay for patients with SLE.

CONCLUSIONS

Agreement between the QFT-G assay and TST in patients with SLE was found to be fair. However, BCG vaccination status, age, and SLEDAI score are all factors that could result in discordance between the two tests. Indeterminate results from the QFT-G assay may be caused by a higher SLEDAI score or increased glucocorticoid dose.