Use of the T-SPOT.TB Assay to Detect Latent Tuberculosis Infection Among Rheumatic Disease Patients on Immunosuppressive Therapy

Position statement of the Spanish Society of Pediatric Rheumatology on infection screening, prophylaxis, and vaccination of pediatric patients with rheumatic diseases and immunosuppressive therapies: Part 1 (screening)

This study provides practical recommendations on infection screening in pediatric patients with immune-mediated rheumatic diseases and immunosuppressive therapies. For this reason, a qualitative approach was applied. A narrative literature review was performed via Medline. Primary searches were conducted using Mesh and free texts to identify articles that analyzed data on infections and vaccinations in pediatric patients with immune-mediated rheumatic diseases and immunosuppressive therapies. The results were presented and discussed in a nominal group meeting, comprising a committee of 12 pediatric rheumatologists from the infections prevention and treatment working group of the Spanish Society of Pediatric Rheumatology. Several recommendations were generated. A consensus procedure was implemented via a Delphi process that was extended to members of the Spanish Society of Pediatric Rheumatology and Vaccine Advisory Committee of the Spanish Association of Pediatrics. Participants to the process produced a score ranging from 0 = totally disagree to 10 = totally agree. Agreement was considered if at least 70% of participants voted ≥ 7. The literature review included more than 400 articles. Overall, 63 recommendations were generated (21 on infection screening) voted by 59 pediatric rheumatologists and other pediatric specialists, all of them achieving the pre-established agreement level. The recommendations on screening cover all the procedures (serology, assessment of risk factors, and other clinical activities) connected with the screening for infections including tuberculosis; hepatitis A, B, and C viruses; measles; mumps; rubella; diphtheria; and other infections. Conclusion: Screening for infections is an essential part of risk management in pediatric patients with immune-mediated rheumatic diseases and immunosuppressive therapies. What is Known: • Infectious diseases and related complications are a major cause of morbidity and mortality in patients with immune-mediated rheumatic diseases. • At present, practical information on infectious prophylaxis in children with rheumatic diseases is limited, and often extrapolated from children with cancer. What is New: • In the absence of evidence, a literature review and a Delphi survey were conducted to establish a series of expert recommendations that would be useful in clinical practice, providing a practical and simple day-to-day approach to be used by pediatric rheumatologists.

Clinical evaluation of the T-SPOT.TB test for detection of tuberculosis infection in northeastern Guangdong Province, China

OBJECTIVE

We evaluated clinical performance of the T-SPOT.TB test for detecting tuberculosis (TB) infection in Meizhou, China.

METHODS

We enrolled 2,868 patients who underwent T-SPOT.TB, smear, and TB-DNA at the same time. The tests' sensitivity and specificity were evaluated and compared in different groups, and in pulmonary TB (PTB) and extrapulmonary TB (EPTB) subgroups. Receiver operator characteristic (ROC) curve analysis was used to evaluate T-SPOT.TB's diagnostic value and determine its cutoff value.

RESULTS

T-SPOT.TB, TB-DNA, and sputum smear sensitivity was 61.44%, 37.12%, and 14.02%; and specificity was 76.49%, 99.20% and 99.60%, respectively. The T-SPOT.TB positive rate was higher in the PTB and EPTB subgroups than in patients with other pulmonary diseases (61.38% and 61.76% vs. 23.34%). The T-SPOT.TB test had better diagnostic accuracy and sensitivity when the positive cutoff value of marker ESAT-6 was 2.5 [area under ROC curve = 0.701, 95%CI 0.687-0.715] and marker CFP-10 was 6.5 [area under ROC curve = 0.669, 95%CI 0.655-0.683].

CONCLUSION

T-SPOT.TB sensitivity was higher than that of TB-DNA or sputum smear, but the specificity was lower. T-SPOT.TB had moderate sensitivity and specificity for diagnosing TB. T-SPOT.TB's new positive cutoff value may be clinically valuable according to ROC analysis.

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.

Quantiferon TB-Gold conversion can predict active tuberculosis development in elderly nursing home residents

AIM

The study was carried out on elderly nursing home residents in Taiwan. We assessed whether the serial QuantiFERON-TB Gold (QFT-G) assay and serial tuberculin skin test (TST) were reliable tools to predict or exclude the development of active tuberculosis (TB).

METHODS

This prospective observational cohort study involved non-bacillus Calmette-Guérin-vaccinated 259 elderly nursing home residents free of active TB at baseline. Of these, 147 were eligible for follow up. Participants underwent serial QFT-G and TST at baseline and 2-year follow up, and were monitored for active TB over 5 years. Agreement between QFT-G and TST, incidence rate ratio, positive predictive value, and negative predictive value for progression to active TB were measured.

RESULTS

During 5-year follow up, three participants developed active TB. The agreement between these two tests was 54.13% (ĸ = 0.167, P = 0.001). The incidence rate ratio was 15.8 (P = 0.016) for the QFT-G-conversion group compared with the TST-positive group at baseline. Positive predictive value for QFT-G conversion groups was 25%. Negative predictive value was 100% for the TST-negative group at baseline.

CONCLUSION

In the elderly nursing home residents, QFT-G conversion is a more reliable tool to predict the development of active TB. Meanwhile, TST is a valuable tool for predicting the chance of not developing active TB.

Diagnosis of latent tuberculosis infection with T-SPOT(®).TB in a predominantly immigrant population with rheumatologic disorders

PURPOSE

The objective of this study is to compare how likely positive tuberculin skin test (TST) and T-SPOT(®).TB (TSPOT) results predict risk factors for tuberculosis in a predominantly immigrant patient population at risk of latent TB infection (LTBI) and with rheumatologic conditions requiring immunomodulatory therapy (IMT).

METHODS

Prospective study conducted at a referral rheumatology clinic. Inclusion criteria included patients on various IMT, including immunosuppressive drugs that could predispose to TB progression. We studied risk factors associated with LTBI, test results, and tests' agreement.

RESULTS

We studied 101 patients. Eighty (79.2 %) were from countries where TB is prevalent and Bacille Calmette-Guérin vaccination is placed routinely. Seventy-four (73.3 %) had rheumatoid arthritis and 92 (90.7 %) were on IMT. Among patients with both TST and TSPOT results, 25 (30.9 %) were TST(+) and 20 (24.7 %) had TSPOT(+) results. Fifteen patients (18.5 %) had TST(+)/TSPOT(+) results, and 51 (63.0 %) had TST(-)/TSPOT(-) results (agreement = 81.5 %; kappa = .54 [95 % CI, .34-.74; P < .001]). Each TSPOT(+) and TST(+) results were independently associated with immigrant status and prior residence in a TB prevalent country after adjustment for immunosuppressive therapy: Adjusted OR(TSPOT+)=6.6 (95 % CI, 1.2-123.3; P = .027); and adjusted OR(TST+)=11.2 (95 % CI, 2.0-209.5; P = .003). Seven out of 10 TST(+)/TSPOT(-) cases had a TST ≥15 mm induration, including three cases with history of TST conversion.

CONCLUSIONS

TST(+) and TSPOT(+) results predict risk factors associated with LTBI independent of immunosuppressive IMT. Some TST(+)/TSPOT(-) results were unlikely to be false-negatives. The combined use of TST and TSPOT appears to be a reasonable diagnostic strategy to evaluate for LTBI in this population.

Diagnosis of latent tuberculosis in patients with systemic lupus erythematosus: T.SPOT.TB versus tuberculin skin test

Early studies in patients with systemic lupus erythematosus (SLE) reported increased incidence of tuberculosis. The tuberculin skin test (TST) is the technique of choice to detect latent tuberculosis infection (LTBI) but has several limitations. Objectives. We compared TST and the newer T.SPOT.TB test to diagnose LTBI in SLE patients. Methods. In this observational cohort study conducted between August 2009 and February 2012, we recruited 92 patients from those attending the SLE clinic of our university hospital. Data recorded were epidemiological and sociodemographic characteristics. Laboratory analyses included TST and T.SPOT.TB tests. Results. Of the patients studied, 92% were women with an average age of 42.7 years. Overall, the degree of correlation between the two tests was low (Kappa index = 0.324) but was better in patients not receiving corticosteroids (CTC)/immunosuppressive (IS) therapy (Kappa = 0.436) and in those receiving hydroxychloroquine (Kappa = 0.473). While TST results were adversely affected by those receiving CTC and/or IS drugs (P = 0.021), the T.SPOT.TB results were not. Conclusion. Although the TST test remains a useful tool for diagnosing LTBI in SLE patients, the T.SPOT.TB test is perhaps better employed when the patient is receiving CTC and/or IS drugs.

Evaluation of screening methods for identification of patients with chronic rheumatological disease requiring tuberculosis chemoprophylaxis prior to commencement of TNF-α antagonist therapy

BACKGROUND

Patients undergoing tumour necrosis factor (TNF)-α antagonist therapy are at increased risk of latent tuberculosis infection (LTBI) reactivation. The aim of this study was to determine the optimum available screening strategy for identifying patients for tuberculosis (TB) chemoprophylaxis.

METHODS

We conducted a prospective observational study of consecutive adults with chronic rheumatological disease referred for LTBI screening prior to commencement of TNF-α antagonist therapy. All patients included had calculation of TB risk according to age, ethnicity and year of UK entry, as described in the 2005 British Thoracic Society (BTS) guidelines and measurement of tuberculin skin test (TST) and T.Spot.TB.

RESULTS

There were 187 patients included in the study, with 157 patients (84%) taking immunosuppressants. 137 patients would require further risk stratification according to the BTS algorithm, with 110 (80.3%) classified as being at low risk of having LTBI. There were 39 patients (35.5%) who were categorised as low risk but were either TST and/or T.Spot positive and would not have received chemoprophylaxis according to the BTS algorithm. Combination of all three methods (risk stratification and/or positive T.Spot and/or positive TST) identified 66 patients out of 137 who would potentially be offered chemoprophylaxis, which was greater than any single test or two-test combination.

CONCLUSION

Performing both a TST and T.Spot in patients on immunosuppressants prior to commencement of TNF-α antagonist therapy gives an additional yield of potential LTBI compared with use of risk stratification tables alone. Our results suggest that use of all three screening modalities gives the highest yield of patients potentially requiring chemoprophylaxis.

Interferon-gamma release assays versus tuberculin skin testing in patients with rheumatoid arthritis

OBJECTIVE

The aim of this study was to analyze the results of interferon-gamma release assays (IGRAs) and tuberculin skin tests (TST) performed to detect latent tuberculosis infection (LTBI) in patients with rheumatoid arthritis (RA).

METHODS

Interferon-γ release assays and TST test results were summarized and systematically reviewed.

RESULTS

Four hundred and five RA patients and 339 controls that underwent IGRA and/or TST were identified in seven studies. Five studies were case-control studies and two were cross-sectional studies. Among RA patients, the IGRA positivity rate was 31.6% (89/282; range 11.4%-44.6%), and the TST positivity rate was 23.0% (78/339; range from 14.60% to 45%). Concordance rates ranged from 40% to 76% and discordance rates from 24% to 29.7%. Agreement between IGRAs and TST in RA was poor (69.6%, k = 0.33, 95% CI 0.188-0.478). The IGRA positivity rate was 31.0% in RA and 40.0% in controls, which was not significant (relative risk [RR] 0.802, 95% CI 0.629-1.023, P = 0.075). The TST positivity rate was 24.7% in RA and 50.5% in controls, and this difference was not significant (RR 0.680, 95% CI 0.331-1.339, P = 0.295).

CONCLUSIONS

Positivity rates of IGRA and TST were 31.6 and 23.0%, respectively, in RA patients. Agreement between IGRA and TST results in RA was poor. Our data suggest that both IGRA and TST are needed to detect LTBI in RA.

Interferon-Gamma Release Assays versus Tuberculin Skin Testing for the Diagnosis of Latent Tuberculosis Infection: An Overview of the Evidence

A profusion of articles have been published on the accuracy and uses of interferon-gamma releasing assays. Here we review the clinical applications, advantages, and limitations of the tuberculin skin test and interferon-gamma release assays and provide an overview of the most recent systematic reviews conducted for different indications for the use of these tests. We conclude that both tests are accurate to detect latent tuberculosis, although interferon-gamma release assays have higher specificity than tuberculin skin testing in BCG-vaccinated populations, particularly if BCG is received after infancy. However, both tests perform poorly to predict risk for progression to active tuberculosis. Interferon-gamma release assays have significant limitations in serial testing because of spontaneous variability and lack of a validated definition of conversion and reversion, making it difficult for clinicians to interpret changes in category (conversions and reversions). So far, the most important clinical evidence, that is, that isoniazid preventive therapy reduces the risk for progression to disease, has been produced only in tuberculin skin test-positive individuals.

Comparison of two gamma interferon release assays and tuberculin skin testing for tuberculosis screening in a cohort of patients with rheumatic diseases starting anti-tumor necrosis factor therapy

Gamma interferon release assays (IGRAs) are increasingly used for latent Mycobacterium tuberculosis infection (LTBI) screening in patients with rheumatic diseases starting anti-tumor necrosis factor (anti-TNF) therapies. We compared the performances of two IGRAs, an enzyme-linked immunospot release assay (T-SPOT.TB) and an enzyme-linked immunosorbent assay (QuantiFERON-TB Gold In Tube [QFT-GIT]), to that of tuberculin skin testing (TST) for LTBI screening of 157 consecutive rheumatic patients starting anti-TNF therapies. Among 155 patients with valid results, 58 (37%) were positive by TST, 39 (25%) by T-SPOT.TB assay, and 32 (21%) by QFT-GIT assay. IGRAs were associated more strongly with at least one risk factor for tuberculosis (TB) than TST. Risk factors for a positive assay included chest X-ray findings of old TB (TST), advanced age (both IGRAs), origin from a country with a high TB prevalence, and a positive TST (T-SPOT.TB assay). Steroid use was negatively associated with a positive QFT-GIT assay. The agreement rate between IGRAs was 81% (kappa rate = 0.47), which was much higher than that observed between an IGRA and TST. If positivity by either TST or an IGRA was required for LTBI diagnosis, then the rate of LTBI would have been 46 to 47%, while if an IGRA was performed only for TST-positive patients, the respective rate would have been 11 to 17%. In conclusion, IGRAs appear to correlate better with TB risk than TST and should be included in TB screening of patients starting anti-TNF therapies. In view of the high risk of TB in these patients, a combination of one IGRA and TST is probably more appropriate for LTBI diagnosis.

T-SPOT.TB assay usage in adults and children

The diagnosis and treatment of TB infection is one of the public health priorities. Until recently, diagnosis of TB infection has been based on the tuberculin skin test (TST). However, this is neither 100% sensitive nor specific for the diagnosis of TB infection owing to its many drawbacks. More recently, T-cell-based IFN-γ release assays (IGRAs) have been developed. In this article, we review the clinical performance of one of the IGRAs, T-SPOT.TB assay, for the diagnosis of TB infection in adults and children. We discuss the principle of the assay, its utility in active TB diseases, latent TB infection and the performance of the test in specialized subgroups of patients, such as immunocompromised individuals. When compared with the TST, the T-SPOT.TB assay has better specificity in bacillus Calmette-Guérin-vaccinated individuals, and data suggest that T-SPOT.TB may be more sensitive than the TST. Data in groups at high risk of progression to disease support the idea that T-SPOT.TB performs better than the TST. In addition, application of T-SPOT.TB by using bodily fluids such as cerebrospinal fluid, bronchoalveolar lavage fluid and pleural fluid may offer new diagnostic approaches in extrapulmonary TB disease. Although IGRAs cannot distinguish active TB disease from latent TB infection, these assays perform better than the TST for the detection of TB infection.

Challenges in Diagnosing Latent Tuberculosis Infection in Patients Treated with Tumor Necrosis Factor Antagonists

Reactivation of latent tuberculosis infection (LTBI) is well recognized as an adverse event associated with anti-tumor necrosis factor-α (anti-TNF-α) therapy. The strengths and weaknesses of current techniques for detecting LTBI in patients with chronic inflammatory diseases such as rheumatoid arthritis (RA) and psoriasis have not been fully examined. T cell hyporesponsiveness due to immunosuppression caused by illness or drugs, referred to as anergy, may produce false-negative tuberculin skin test (TST) and interferon-γ release assay (IGRA) results. The literature suggests that anergy may influence screening performance of TST and IGRA tests in candidates for anti-TNF-α therapy. Conversely, the potential for false-positive TST and IGRA results must be considered, as treatment for LTBI may be associated with significant morbidity. This review examines the reliability issues related to LTBI diagnostic testing and provides practical direction to help prevent LTBI reactivation and facilitate successful anti-TNF-α treatment.

Choice of Biologic Therapy for Patients with Rheumatoid Arthritis: The Infection Perspective

Biologicals revolutionized the treatment of Rheumatoid Arthritis (RA). The targeted suppression of key inflammatory pathways involved in joint inflammation and destruction allows better disease control, which, however, comes at the price of an elevated infection risk due to relative immunosuppression. The disease-related infection risk and the infection risk associated with the use of TNF-α inhibitors (infliximab, adalimumab, etanercept, golimumab and certolizumab pegol), rituximab, abatacept and tocilizumab are discussed. Risk factors clinicians need to take into account when selecting the most appropriate biologic therapy for RA patients, as well as precautions and screening concerning a number of specific infections, such as tuberculosis, intracellular bacterial infections, reactivation of chronic viral infections and HIV are reviewed.

Evidence-based comparison of commercial interferon-gamma release assays for detecting active TB: a metaanalysis

Test accuracy of interferon-gamma release assays (IGRAs) for diagnosing TB differs when using older or precommercial tools and inconsistent diagnostic criteria. This metaanalysis critically appraises studies investigating sensitivity and specificity of the commercial T-Spot.TB and the QuantiFERON-TB Gold In-Tube Assay (QFT-IT) among definitely confirmed TB cases. We searched Medline, EMBASE, and Cochrane bibliographies of relevant articles. Sensitivities, specificities, and indeterminate rates were pooled using a fixed effect model. Sensitivity of the tuberculin skin test (TST) was evaluated in the context of IGRA studies. In addition, the rates of indeterminates of both IGRAs were assessed. The pooled sensitivity of TST was 70% (95% CI, 0.67-0.72) compared with 81% (95% CI, 0.78-0.83) for the QFT-IT and 88% (95% CI, 0.85-0.90) for the T-Spot.TB. Sensitivity increased to 84% (95%CI, 0.81-0.87) and 89% (95% CI, 0.86-0.91) for the QFT-IT and T-Spot.TB, respectively, when restricted to performance in developed countries. In contrast, specificity of the QFT-IT was 99% (95% CI, 0.98-1.00) vs 86% for the T-Spot.TB (95% CI, 0.81-0.90). The pooled rate of indeterminate results was low, 2.1% (95% CI, 0.02-0.023) for the QFT-IT and 3.8% (95% CI, 0.035-0.042) for the T-Spot.TB, increasing to 4.4% (95% CI, 0.039-0.05) and 6.1% (95% CI, 0.052-0.071), respectively, among immunosuppressed hosts. The newest commercial IGRAs are superior, in comparison with the TST, for detecting confirmed active TB disease, especially when performed in developed countries.