Tuberculin Skin Test In Patients Research Articles

An updated systematic review on the applied TST and IGRA Test for diagnosing LTBI in patients treated with TNF-α inhibitor drugs

Present systematic review was designed to compare the efficacy of interferon-γ release assays (IGRAs) and tuberculin skin test (TST) for diagnosing latent tuberculosis infection (LTBI) in patients subjected to the anti-TNF-α therapy. The MEDLINE (Ovid), PubMed, Embase, Scopus, Cochrane library, and Web of Science ISI databases were searched for selecting studies to compare the efficiency of IGRAs [QuantiFERONTB Gold (QFT-GT), QuantiFERON-TB Gold In-Tube (QFT-GIT)and T-SPOT.TB] and TST in patients under the anti-TNF-α therapy. After evaluating all studies, we systemically reviewed the results of 37 studies with a total sample size of 8584 patients. The agreement between IGRASs and TST was poor to moderate, however, the anti-TNF-α therapy mostly decreased the percentage of this agreement. BCG vaccination could cause false results of TST assay. The developed active TB in patients with IGRAs positive results during follow-up showed lower than TST positive patients. In conclusion, in the treated patients with anti-TNF-α with previous BCG vaccination, IGRAs might be the better assay to diagnosis LTBI by reducing the false results rate in comparison with the TST. However, more investigations should be done to compare the advantage of IGRAs with conventional test in the treated patients with TNF-α antagonists.

Variations of tuberculin skin test in patients with rheumatologic disorders and under anti-TNF treatment

Aim: Nowadays PPD is the most inexpensive and easy to apply modality of test in identification of latent tuberculosis infection. Isoniazid (INH) prophylaxis must be given before usage of anti-TNF-α agents for patients. We aimed to investigate the change in Tuberculin skin test (TST) levels and Isoniazid (INH) prophylaxis rates in patients with inflammatory rheumatic diseases treated with anti-tumor necrosis factor alpha (TNF-α) agents. Methods: A cross-sectional study was planned. Patients with inflammatory rheumatic diseases treated with anti-TNF agents were included in the study. Demographic data, initial TST level and INH prophylaxis had obtained from patient’s files. Control TST tests had done at tuberculosis dispensaries in different time periods such as 1-2 / 2-3 / 3-4 / ≥4 years of anti TNF treatment. INH prophylaxis rates according to initial and control TST tests were compared. The relationship between INH prophylaxis and duration of anti-TNF therapy were examined.Results: A total of 117 patients were included in the study. The mean age of the patients (81 male, 36 female) was 40.4±12.90. The control TST levels was significantly higher than initial TST (p=0.001). INH prophylaxis was given to total 99 (84.6%) of 117 patients (to 63 (53.8%) according to initial and to 36 (30.8%) according to control TST tests). There was no relationship between duration of anti TNF therapy and INH prophylaxis initiation (p=0.180). Conclusion: Anti-TNF treatments may reduce the rates of false-negative TST in patients with rheumatic diseases and latent tuberculosis (LTBI) at any stage of the treatment. Therefore, LTBI, which is not determined with initial TST tests, may be determined with TST test applied in the later stages of anti-TNF treatment, and the risk of active tuberculosis can be reduced by INH prophylaxis in this patients.

Tuberculin skin test response in patients with juvenile idiopathic arthritis on anti-TNF therapy

The aim of this study is to evaluate the effect of biologic drugs on the tuberculin skin test in patients with juvenile idiopathic arthritis. A total of 234 biologic drug-using juvenile idiopathic arthritis patients and 45 healthy controls were enrolled in the study. The tuberculin skin test results of the patients, which had been routinely provided during follow-up, were obtained from the patient files. Tuberculin skin test values of ≥5 mm were considered to be positive. The mean diameter of tuberculin skin test induration was 4.99 ± 6.84 mm (IQR: 0–10 mm) and 7.83 ± 3.47 mm (IQR: 0–16 mm) in patients and controls, respectively (P < 0.05). Tuberculin skin test positivity (≥5 mm) was found in 96 (41%) and 38 (84.4%) of patients and controls, respectively (P < 0.001). There was no induration in 125 (53.4%) patients and 3 (6.6%) healthy controls, respectively (P < 0.001). In the patients with juvenile idiopathic arthritis who were using biologic drugs, tuberculin skin test induration was significantly lower compared to the control group. Tuberculin skin tests alone seem inadequate for recognition of latent tuberculosis in juvenile idiopathic arthritis patients on anti-TNF therapy.

A retrospective review of the two-step tuberculin skin test in dialysis patients.

BackgroundReactivation of latent Mycobacterium tuberculosis infection (LTBI) is a health concern for patients on dialysis or receiving a kidney transplant, as these patients are often immunosuppressed. The most frequently used test for LTBI screening in this population is the tuberculin skin test (TST). The diagnostic accuracy (sensitivity and specificity) of the TST in a contemporary North American or Western European dialysis population is unknown.ObjectivesOur objective was to determine the diagnostic accuracy and clinical utility of the two-step TST in patients receiving dialysis.DesignThis is a retrospective cohort study.SettingThis study is set at four tertiary dialysis units across Winnipeg, Manitoba.PatientsThere are 483 chronic hemodialysis and peritoneal dialysis patients in the study.MeasurementsThe measurements are sensitivity and specificity of the TST with respect to abnormal chest X-ray.MethodsAll patients received a two-step TST and assessment of risk factors for prior tuberculosis (TB) infection between February 2008 and December 2008. This cohort was retrospectively linked to our tuberculosis registry to ascertain if prophylaxis was received for LTBI.ResultsAt an induration cutoff of 5 mm, 62 (13 %) patients had a positive two-step TST. Patients with a known Bacillus Calmette-Guérin (BCG) vaccination were more likely to test positive (50 % of those with a positive TST had a BCG versus 34 % with a negative TST, p = 0.05). Using a diagnostic gold standard of an abnormal chest X-ray as a proxy for LTBI, the sensitivity of the TST was only 14 % and the specificity was 88 %. Only 8 of 62 patients with a positive TST (13 %) received prophylaxis for LTBI. None of the patients who tested negative were treated.LimitationsThere is a lack of a truly accurate gold standard for LTBI.ConclusionsThe TST has limited diagnostic and clinical utility for LTBI screening in patients on dialysis. Further research into the diagnostic accuracy of interferon-gamma release assays and a revision of LTBI screening guidelines in patients on dialysis should be considered.Electronic supplementary materialThe online version of this article (doi:10.1186/s40697-016-0119-4) contains supplementary material, which is available to authorized users.

Association of clinical properties and compatibility of the QuantiFERON-TB Gold In-Tube test with the tuberculin skin test in patients with psoriasis.

Individuals with psoriasis show conflicting responses to the tuberculin skin test (TST), a commonly used screening test for latent tuberculosis infection. An alternative to TST is QuantiFERON-TB Gold In-Tube test (QFT-GIT), an in vitro interferon-gamma release assay. This study aimed to determine the effect of the clinical properties of psoriasis (disease severity and koebnerization status) on TST results and the agreement between the TST and QFT-GIT results in psoriatic patients. One hundred patients with mild to severe psoriasis were enrolled in this prospective cross-sectional study. Psoriasis properties, including disease severity (psoriasis area and severity index score and koebnerization status), latent tuberculosis infection risk factors, and bacillus Calmette-Guérin vaccination history, were recorded. All patients underwent a TST and QFT-GIT. TST positivity cut-off point was ≥10 mm for bacillus Calmette-Guérin-vaccinated patients and ≥5 mm for non-vaccinated patients. Psoriasis area and severity index scores and koebnerization status did not correlate with TST diameters. Only one of the 23 koebnerization-positive patients developed koebnerization in response to TST. QFT-GIT positivity was prominently higher in the TST-positive group, and this was the only factor that differed between the TST-positive and TST-negative groups (P < 0.001). Tuberculin skin test results were not affected by psoriasis severity or koebnerization status. QFT-GIT positivity was prominently higher in the TST-positive group (P < 0.001). Overall agreement between TST and QFT-GIT results was moderate (κ = 0.413). Concurrent negativity (44%) was higher than concurrent positivity (27%).

Sa1266 Interferon-γ Release Assay Versus Tuberculin Skin Test in Patients With Moderate-to-Severely Active Ulcerative Colitis: Results From the PURSUIT UC Program

Objective: To report results of an interferonΥ release assay (IGRA) vs standard tuberculin skin test (TST) as a screening tool for latent TB infection in patients with UC in PURSUIT. Methods: Patients with moderately to severely active UC were screened for latent TB using the standard TST and the IGRA to assess eligibility for entry into the induction studies of golimumab (PURSUIT-SC [C0524T17]and PURSUIT-IV [C0524T1]Any patient with a newly identified positive finding for TB on a diagnostic test in whom there was no evidence of active TB was permitted to enter provided appropriate treatment for latent TB was initiated before or at the time of the first dose of study agent. TST was performed according to the Mantoux method, using 5 tuberculin units (TU) of purified protein derivative (PPD) standard or 2 TU of PPD RT-23. The TST was deemed positive for latent TB infection according to the local country guidelines for defining an immunosuppressed host or, in the absence of local guidelines, according to the presence of induration >5mm. The IGRA used to screen for latent TB was the QuantiFERON-TB Gold In-Tube test. Overall IGRA and TST results were assessed. The impact of prior BCG vaccination and concomitant medication (ie corticosteroids and/or immunomodulators ) on outcome was assessed. Results: 1283 patients had both IGRA and TST screening prior to GLM treatment. Among these patients, 8.7% had at least one test yielding positive findings for latent TB, including 6.2% with positive results

Discordance of two interferon-γ release assays and tuberculin skin test in patients with uveitis

AimsTo describe interferon-γ release assay (IGRA) and IGRA/tuberculin skin test (TST) discordance and their associated factors in patients with uveitis.MethodsProspective study of 102 consecutive new patients presenting with uveitis to...

Utility of QuantiFERON-TB Assay for Prediction of Tuberculosis Development in Kidney Transplant Patients in an Intermediate-Tuberculosis-Burden Country: Lack of Evidence for Enhanced Prediction for Short-Term Tuberculosis Development

IntroductionAlthough a latent tuberculosis (TB) infection is a risk factor for active TB, the diagnosis of latent TB infection is difficult in end-stage renal disease patients. Patients and MethodsWe retrospectively compared the results of the QuantiFERON-TB (QFT) test and the tuberculin skin test in patients on the waiting list for kidney transplantation (KT), and investigated whether the QFT test can predict TB development in KT recipients in an intermediate-TB-burden country. ResultsThe incidence of post-KT TB was 283 cases/100,000 patient-years among 1274 KT recipients at the Seoul National University Hospital. The overall standardized incidence ratio of TB was 4.358 compared with the general population. A past history of TB infection, smoking history, myocardial infarction after KT, and pneumocystis infection were significant predictors of subsequent TB development (adjusted odds ratios were 3.618, 2.959, 9.993, and 5.708, respectively). Among the 129 recipients who had the QFT test, 42 patients (32.5%) had positive a QFT. At a median follow-up of 8.4 ± 6.8 months, 1 patient with positive QFT results developed TB after KT, and 1 of the 87 patients with negative QFT results developed TB after KT. In both of these 2 cases, active TB developed despite isoniazid prophylaxis. Among 272 patients on the waiting list for KT, the tuberculin skin test and QFT were positive in 22.8% and 35.3%, respectively. The degree of agreement between the 2 tests was poor (κ = 0.352). ConclusionsThe QFT test did not predict subsequent short-term TB development. Furthermore, a long-term and larger-scale study is needed to confirm our results.

Screening for Latent Tuberculosis Infection in Patients with Chronic Inflammatory Arthritis: Discrepancies Between Tuberculin Skin Test and Interferon-γ Release Assay Results

Screening for latent tuberculosis infection (LTBI) is mandatory before initiating biologics in patients with chronic inflammatory arthritis (CIA). However, few studies have evaluated the discrepancies between the results of tuberculin skin test (TST) and interferon-γ release assays (IGRA) in these patients. The purpose of our study was to investigate factors associated with TST and IGRA results in a large cohort of patients with CIA before the introduction of biologics. A total of 563 consecutive patients with CIA (293 rheumatoid arthritis, 270 spondyloarthritis) and eligible for biologics were prospectively enrolled. Demographic, clinical, and biological data were recorded. Risk factors for LTBI were assessed. All patients underwent a TST, a chest radiograph, and an IGRA test (T-SPOT.TB). Agreement between the 2 tests was low (κ = 0.16). The bacillus Calmette-Guerin (BCG) status was significantly associated with discordance between the 2 tests (p = 0.004). The TST positivity rate was 34.8%. Factors associated with a negative TST were female sex (p = 0.02) and immunosuppressive treatment (p = 0.003). The only LTBI risk factor associated with TST positivity was an abnormal chest radiograph (p = 0.02). T-SPOT.TB was positive in 21.7% of patients and indeterminate in 15.6%. Previous active TB and chest radiograph abnormalities were associated with IGRA positivity (p = 0.008 and p = 3.9 × 10(-5), respectively). The BCG vaccination was associated with negative IGRA (p = 3 × 10(-4)). Indeterminate IGRA results were associated with age, C-reactive protein, and immunosuppressive treatment (p = 0.005, 0.007, and 0.004, respectively). Our data support the combined use of T-SPOT.TB and TST in patients with CIA before biologics introduction. However, despite these good diagnostic values, indeterminate results may complicate the use of IGRA.

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

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

How to use: interferon γ release assays for tuberculosis

Diagnosis and treatment of latent tuberculosis infection (LTBI) is important to reduce risk of progression to active tuberculosis (TB) disease. For the past century the tuberculin skin test (TST) has...

The effect of hepatotropic virus (HBV-HCV) infections on tuberculin skin test in patients with cirrhosis

To optimize the detection of infected persons and to treat latent tuberculosis infection are essential in patients taking part in a liver transplantation program. The tuberculin skin test is currently used to detect Mycobacterium tuberculosis infection and has widespread usage. This study aimed to evaluate the effect of hepatitis B and C viruses on tuberculin skin test results in patients taking part in the liver transplantation program in our center. A total of 90 cirrhosis patients who participated in the liver transplantation program between January 2004 and February 2005 were included in this study. None of the patients displayed signs of active tuberculosis during the follow-up. The mean indurations of the tuberculin skin test were found to be 14.7±6.9 mm in patients with a viral etiology and 6.1±5.4 mm in those with a non-viral etiology. The tuberculin skin test findings were significantly higher in end-stage liver disease caused by viruses than those with a non-viral etiology (p<0.05). The mean induration of the tuberculin skin test in Child B patients was found to be 7.15±6.4 mm, while in Child C patients it was 12.64±7.5 mm. In Child C patients, the tuberculin skin test scores were significantly higher than in Child B patients (p<0.05). These observations show the need for new methods to detect latent Mycobacterium tuberculosis infection in liver transplant candidates. Further research is needed to understand the reasons for the higher tuberculin skin test results with a viral etiology and in Child C patients.

Clinical utility of QuantiFERON-TB GOLD In-Tube and tuberculin skin test in patients with tuberculous pleural effusions

Interferon gamma release assays are used for diagnosing latent tuberculosis (TB); however, their role in diagnosing tuberculous pleural effusion (TPE) is not defined. The aim of this study was to evaluate the usefulness of the QuantiFERON-TB Gold In-Tube assay (QFT-IT) and compare this assay with the tuberculin skin test (TST) for diagnosing TPE in settings where tuberculosis is endemic and bacillus Calmette–Guérin vaccination is mandatory. The TST and QFT-IT test were conducted prospectively with 101 patients presenting with clinically suspected TPE. Of the 97 evaluable subjects, 54 had TPE. The sensitivity, specificity, positive predictive value, and negative predictive value were, respectively, 76.9%, 61.1%, 74.1%, and 64.7% for QFT-IT; 72.5%, 71.7%, 77.1%, and 66.7% for TST; and 83.7%, 45.7%, 68.3%, and 66.7% for QFT-IT plus TST. Thus, the QFT-IT test may be more useful than the TST for diagnosing TPE. Although the combination of QFT-IT and TST had higher sensitivity, it had poor specificity owing to the high prevalence of latent TB in our setting.

Prednisolone treatment affects the performance of the QuantiFERON gold in-tube test and the tuberculin skin test in patients with autoimmune disorders screened for latent tuberculosis infection

During screening for latent tuberculosis infection (LTBI), before anti-tumor-necrosis-factor-α treatment, most patients are already receiving immunosuppressive therapy. The objective was to evaluate the performance of the QuantiFERON Gold In-Tube (QFT-IT) and the Tuberculin Skin Test (TST). A prospective multicenter study included 248 patients with ulcerative colitis (39), Crohn's disease (54), rheumatoid arthritis (111), and spondylo-arthropathy (44). QFT-IT was positive in 7/248 (3%), negative in 229 (92%), and indeterminate in 12 (5%). TST was positive in 54/238 (23%) patients. Chest x-ray was suspect for tuberculosis in 5/236 (2%), and 35/167 (21%) had ≥1 risk-factors for infection with Mycobacterium tuberculosis. The main finding was a pronounced negative effect on QFT-IT and TST performance associated with prednisolone treatment. During prednisolone treatment interferon gamma (IFN-γ) response to mitogen stimulation was impaired (median IFN-γ response 4.9 IU/mL; interquartile range [IQR] 0.8 to ≥10.0) compared to patients 1) not receiving corticosteroids (median ≥10.0; IQR 5.0 to ≥10.0; P = 0.0015) or 2) receiving long-acting corticosteroids (median >10.0; IQR 9.7 to >10.0; P = 0.0058). Prednisolone treatment was strongly associated with negative TST, adjusted odds ratio (AOR) 0.22 (0.1-0.8; P = 0.018), and with an increased risk of indeterminate QFT-IT results AOR 16.1 (4.1-63.2; P < 0.001), whereas no negative effect was found for long-acting corticosteroids. Doses of ≥10 mg prednisolone were associated with a 27% risk of indeterminate results. Single use of azathioprine, methotrexate, or 5-aminosalicylate (5-ASA) did not affect the test results. Oral prednisolone severely suppressed QFT-IT and TST performance, whereas the long-acting corticosteroids methotrexate, azathioprine, and 5-ASA did not have a similar detrimental effect. Patients should be screened for LTBI with QFT-IT or TST prior to initiation of prednisolone therapy and negative QFT-IT or TST results interpreted with caution in patients treated with any corticosteroid until further data are available.

The Positive Predictive Value of T-Spot.TB and Tuberculin Skin Test in Patients with Silicosis

The Positive Predictive Value of T-Spot.<i>TB</i> and Tuberculin Skin Test in Patients with Silicosis

Tuberculin skin test for the diagnosis of latent tuberculosis during renal replacement therapy in an endemic area: A single center study

Patients on renal replacement therapy (RRT) are at-risk for developing tuberculosis (TB). There is limited information on tuberculin skin test (TST) and its predictability for development of TB. In this prospective cohort study, patients taken for RRT were included. Patients with active TB were excluded. TST was done with 5-tuberculin unit. In addition to TST, age, sex, diabetes as basic disease, number of dialysis and blood transfusion (BT), pre-transplant TB, hepatitis B and C infections and type of immunosuppression were correlated with the development of TB. Of the 200 patients included, TST was positive in 21 and negative in 179. In TST negative group, 20 (11.1%) and in TST positive group 5 (23.8%) patients developed TB. TB free survival in two groups was similar (P = 0.08). On multivariate Cox regression analysis, hazard of development of TB by TST was 2.7 [P = 0.11, confidence interval (CI) 0.78-9.7]. There was no difference between TST non-responsive and TST negative patients (P = 0.18). Sensitivity and specificity of TST for predicting TB was only 20 and 9%, respectively. Our study shows that TST in patients on dialysis is an insensitive and nonspecific test to predict development of active TB.

Comparison of tuberculin skin test and QuantiFERON-TB gold in tube test in patients with chronic inflammatory diseases living in a tuberculosis endemic population

We aimed to compare tuberculin skin test (TST) and QuantiFERON-TB gold in tube (QFT-IT) in patients with chronic inflammatory diseases living in a population where tuberculosis is endemic and BCG vaccination is routine. Twenty-five patients with rheumatoid arthritis (RA), 16 patients with spondilarthropathy (SpA) and 7 healthy volunteers were recruited in the study. Blood samples were collected for QFT-IT test followed by TST. TST was considered to be positive with an enduration of 5 mm and over in patients with RA and SpA. The cutoff point for TST for the healthy control (HC) was 10 mm. Median TST result of patients who were using immunosuppressive drugs was significantly lower than that of patients who were not [5 (14.5), 13.5 (9.5), respectively, P = 0.04]. Poor agreement between TST and QFT-IT was seen in patients with RA (kappa = 0.141) and in patients with SpA (kappa = 0.190). We found poor concordance between QFT-IT and TST in patients with chronic inflammatory diseases, and TST response was suppressed in patients treated with immunosuppressive drugs.

Comparison of Interferon-Gamma Release Assay Versus Tuberculin Skin Test for Tuberculosis Screening in Inflammatory Bowel Disease

Comparison of Interferon-Gamma Release Assay Versus Tuberculin Skin Test for Tuberculosis Screening in Inflammatory Bowel Disease

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The activation of latent tuberculosis (TB) can be a problem in patients with inflammatory bowel disease (IBD) treated with biologicals. So far, the tuberculin skin test (TST) and chest x-rays were routinely used to detect TB, and used in various IBD trials. Our paper (Am J Gastroenterol 2008;103:2799–2806) described the poor correlation between an interferon (IFN)-γ release assay (IGRA; Quantiferon-TB Gold In-TubeTest [QFT-G-IT]) and the TST. There are practical disadvantages of the TST (2 visits), and the false-positive results in BCG-immunized people and the false-negative results TST in patients under immunosuppression clearly limit the usefulness of this test.In our study, blood samples were taken and then the TST was performed. Thus, the TST was not able to influence the QFT-G-IT (theoretical risk of a false-positive result). Meanwhile, we gained more experience with QFT-G-IT in daily practice. So far, we have not yet observed TB in patients with a negative test. However, others showed that QFT-G-IT may not detect latent or active TB, especially in case of lymphocytopenia (J Infect Chemother 2007;13:414–417; Infection 2008;Dec 10 [Epub ahead of print]). Unfortunately, there is no gold standard for the diagnosis of latent TB. The relatively low positive predictive value of the IGRAs in active TB, however, may limit their usefulness in clinical practice (Chest 2007;132:959–965). Because there may be a small risk that the QFT-G-IT overlooks latent and active TB, the test does not replace a carefully clinical workup of our patients. The indeterminate results of QFT-G-IT in some patients are further limitations of this test. IGRAs certainly improved our diagnostic yield, but are still not optimal. The activation of latent tuberculosis (TB) can be a problem in patients with inflammatory bowel disease (IBD) treated with biologicals. So far, the tuberculin skin test (TST) and chest x-rays were routinely used to detect TB, and used in various IBD trials. Our paper (Am J Gastroenterol 2008;103:2799–2806) described the poor correlation between an interferon (IFN)-γ release assay (IGRA; Quantiferon-TB Gold In-TubeTest [QFT-G-IT]) and the TST. There are practical disadvantages of the TST (2 visits), and the false-positive results in BCG-immunized people and the false-negative results TST in patients under immunosuppression clearly limit the usefulness of this test. In our study, blood samples were taken and then the TST was performed. Thus, the TST was not able to influence the QFT-G-IT (theoretical risk of a false-positive result). Meanwhile, we gained more experience with QFT-G-IT in daily practice. So far, we have not yet observed TB in patients with a negative test. However, others showed that QFT-G-IT may not detect latent or active TB, especially in case of lymphocytopenia (J Infect Chemother 2007;13:414–417; Infection 2008;Dec 10 [Epub ahead of print]). Unfortunately, there is no gold standard for the diagnosis of latent TB. The relatively low positive predictive value of the IGRAs in active TB, however, may limit their usefulness in clinical practice (Chest 2007;132:959–965). Because there may be a small risk that the QFT-G-IT overlooks latent and active TB, the test does not replace a carefully clinical workup of our patients. The indeterminate results of QFT-G-IT in some patients are further limitations of this test. IGRAs certainly improved our diagnostic yield, but are still not optimal. Comparison of Interferon-Gamma Release Assay Versus Tuberculin Skin Test for Tuberculosis Screening in Inflammatory Bowel DiseaseGastroenterologyVol. 136Issue 4PreviewSchoepfer AM, Flogerzi B, Fallegger S, et al. (Department of Gastroenterology, Inselspital/University of Bern, Bern, Switzerland). Comparison of interferon-gamma release assay versus tuberculin skin test for tuberculosis screening in inflammatory bowel disease. Am J Gastroenterol 2008;103:2799–2806. Full-Text PDF

QuantiFERON TB-2G test for patients with active tuberculosis stratified by age groups

We evaluated the usefulness of the QuantiFERON TB-2G (QFT-2G) test and the tuberculin skin test (TST) in patients with active tuberculosis (TB) disease stratified by age in 10-year increments. Although the positive rate on TST was over 80% in younger patients aged < or =9 years, it decreased to 55% in patients of aged 70-79 years and 33% in patients aged over 80 years. However, the positive rate on QFT-2G test was over 80% for the age groups between 10-19 and 60-69 years, excluding younger patients aged < or =9 years. Furthermore, the rate was 79% in patients aged 70-79 years and 75% in patients over 80 years of age. The positive response rate of the QFT-2G test was significantly higher than that of the TST in patients over 50 years of age. The indeterminate result of the QFT-2G test increased with age and it is suggested that this result is concerned with the severity of underlying diseases in patients with active TB disease. Although the positive rate on QFT-2G test decreased with age in adults, it is thought to be a useful supportive diagnostic method for active TB disease compared to the TST, except in younger patients aged < or =9 years old.