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1.  Tuberculosis in pediatric patients treated with anti-TNFα drugs: a cohort study 
Adult patients receiving anti-TNFα drugs are at increased risk of tuberculosis (TB), but studies in pediatric populations are limited, and the best strategy for latent tuberculosis infection (LTBI) screening in this population remains controversial. We describe the prevalence of LTBI prior to anti-TNFα therapy and the long-term follow-up after biological treatment initiation in a cohort of children and adolescents.
Cohort observational study in children and adolescents receiving anti-TNFα agents in a tertiary-care pediatric hospital. LTBI was ruled out prior to the implementation of anti-TNFα drugs by tuberculin skin test (TST), and, from March 2012 on, QuantiFERON Gold-In Tube® test (QTF-G). During anti-TNFα treatment, patients were evaluated every 6 months for TB with history and physical examination. TST/QTF-G were not repeated unless signs or symptoms consistent with TB arose or there was proven TB contact.
The final cohort consisted of 221 patients (56.1 % female; 261 treatments), of whom 51.7 %/30.0 %/17.3 % were treated with etanercept/adalimumab/infliximab, respectively, for a variety of rheumatic diseases (75.6 %), inflammatory bowel disease (20.8 %), and inflammatory eye diseases (3.6 %). The median (IQR) age at diagnosis of the primary condition was 6.8 years (2.7–11.0) and the duration of the disease before implementing the anti-TNFα agent was 1.8 years (0.6–4.2). LTBI was diagnosed in 3 adolescent girls (prevalence rate: 1.4 %; 95 % CI: 0.4–4.2) affected with juvenile idiopathic arthritis: TST tested positive in only 1, while QTF-G was positive in all cases (including 2 patients already on etanercept). They all received antiTB chemoprophylaxis and were later (re)treated with etanercept for 24–29 months, without incidences. No incident cases of TB disease were observed during the follow-up period under anti-TNFα treatment of 641 patients-year, with a median (IQR) time per patient of 2.3 years (1.4–4.3).
In our study, the prevalence of LTBI (1.4 %) was similar to that reported in population screening studies in Spain; no incident cases of TB disease were observed. In low-burden TB settings, initial screening for TB in children prior to anti-TNFα treatment should include both TST and an IGRA test, but systematic repetition of LTBI immunodiagnostic tests seems unnecessary in the absence of symptoms or known TB contact.
PMCID: PMC4669612  PMID: 26635208
Inflammatory bowel disease; Interferon-gamma release assays; Juvenile idiopathic arthritis; Tuberculosis; Anti-tumor necrosis factor-alpha drugs
2.  QuantiFERON-TB Gold In-Tube Assay for Screening Arthritis Patients for Latent Tuberculosis Infection before Starting Anti-Tumor Necrosis Factor Treatment 
PLoS ONE  2015;10(3):e0119260.
Patients undergoing anti-tumor necrosis factor (TNF) treatment are at an increased risk of reactivating a latent tuberculosis infection (LTBI). This study evaluated the effectiveness of the QuantiFERON-TB Gold In-Tube (QFT) assay for diagnosing LTBI in arthritis patients undergoing anti-TNF treatment.
We enrolled 342 consecutive patients from August 2007 to October 2013: 176 (51.5%) patients with ankylosing spondylitis and 166 (48.5%) with rheumatoid arthritis. Screening tests included tuberculin skin test (TST) and QFT assay. Positive QFT results, regardless of TST results, were considered an indicator for LTBI treatment.
Bacillus Calmette-Guérin scars were found in 236 (69.0%) patients. Of 342 patients, TST and QFT were positive in 122 (35.7%) and 103 (30.1%) patients, respectively, and discordant in 101 (29.5%) patients. During a median follow-up duration of 41.7 months, five patients (1.5%) developed TB in a median of 20.8 months after initiation of anti-TNF treatment (428/100,000 person-years). TB did not occur in 62 TST+/QFT+ patients who received LTBI treatment. Of 41 TST−/QFT+ patients who received LTBI treatment, one (2.4%) developed TB 20.5 months after starting anti-TNF treatment (705/100,000 person-years). Of 60 TST+/QFT− patients who did not receive LTBI treatment, two (3.3%) developed TB 20.8 and 22.0 months after starting anti-TNF treatment (871/100,000 person-years). Of 179 TST−/QFT− patients, two (1.1%) developed TB 7.2 and 22.7 months, respectively, after initiating anti-TNF treatment (341/100,000 person-years). TB incidence rate during the follow-up period did not differ among TST−/QFT+, TST+/QFT−, and TST−/QFT− patients (P = 0.661).
QFT might be used instead of TST for diagnosing LTBI in patients before starting anti-TNF therapy in countries, such as Korea, where the TB prevalence is intermediate and the BCG vaccination is mandatory at birth. In the absence of a true gold standard test for LTBI, however, there is still a risk of TB development during anti-TNF treatment.
PMCID: PMC4352032  PMID: 25746854
3.  Identification of latent tuberculosis infection in rheumatic patients under consideration for treatment with anti-TNF-α agents 
Immunosuppressive therapy with anti-tumour necrosis factor-α (TNF-α) agents in rheumatic patients modulates the immune system and may increase the risk of reactivating infections that are normally maintained in a latent state, such as tuberculosis. The purpose of this study was to analyse the value of QuantiFERON TB Gold In-Tube (QFT IT) and tuberculin skin test (TST) in BCG vaccinated patients with rheumatoid arthritis and ankylosing spondylitis who were qualified to receive TNF-α blockers.
Material and methods
Ninety patients with rheumatoid arthritis and ankylosing spondylitis were included in the study. The control group consisted of 20 healthy participants. Chest X-ray, TST and QFT IT were carried out in all persons.
In rheumatic patients positive results of QFT IT and TST tests were identified in 15 cases (16.7%) whereas negative results of both tests were detected in 56 cases (62.2%). In the group of examined patients, 11 (12.2%) had QFT IT-/TST+ test results. In patients with QFT IT+/TST– status one active tuberculosis case was detected. In the control group QFT IT positive results were found in 4 cases (20%) and TST positive in 11 cases (55%). Treatment with TNF-α blockers was introduced in 26 rheumatology patients with the following test status: 3 with QFT IT+/TST+; 20 with QFT IT-/TST-; 3 with QFT IT-/TST+.
In the BCG vaccinated population the QFT IT assay may potentially improve the identification and selection for therapy for latent TB infection before treatment with anti-TNF agents.
PMCID: PMC3598128  PMID: 23515560
QuantiFERON-TB Gold In-Tube; tuberculin skin test; rheumatoid arthritis; latent tuberculosis; anti-TNF-α therapy
4.  Prevalence of Latent Tuberculosis Infection among Health Care Workers in South Korea: A Multicenter Study 
We investigated the prevalence of latent tuberculosis infection (LTBI) among the health care workers (HCWs) and analyzed its risk factors in South Korea.
A standard questionnaire regarding the baseline demographics and risk factors for LTBI was given to each participant and tuberculin skin test (TST), QuantiFERON-TB GOLD In-Tube (QFT-GIT) assay, and chest radiography were performed.
A total of 493 participants, 152 (30.8%) doctors and 341 (69.2%) nurses were enrolled in eight tertiary referral hospitals. The mean age of the subjects was 30.6 years old, and 383 (77.7%) were female. Of the 152 doctors, 63 (41.4%) and 36 (23.7%) were positive by TST and by QTF-GIT, respectively, and among the 341 nurses, 119 (34.9%) and 49 (14.4%) had positive TST and QFT-GIT results, respectively. Overall, the agreement between the two tests was 0.22 by the chance corrected proportional agreement rate (kappa coefficient) in 493 subjects. Experience of working in tuberculosis (TB)-related departments was significantly associated with positive LTBI test results by QFT-GIT assay, not by TST. In multivariate analysis, only age was independently associated with increased risk of a positive TST result, while age and experience of working in TB-related departments (odds ratio, 2.29; 95% confidence interval, 1.01-5.12) were independently associated with increased risk of a positive QFT-GIT result.
A high prevalence of LTBI was found among South Korean HCWs. Considering the association between the experience of working in TB-related departments and high risk of LTBI, QFT-GIT may be a better diagnostic test for LTBI than TST in HCWs.
PMCID: PMC3741469  PMID: 23946754
Latent Tuberculosis; Health Personnel; Tuberculin Test; Interferon-gamma Release Tests; Republic of Korea
5.  Added Value of QuantiFERON TB-Gold in-Tube for Detecting Latent Tuberculosis Infection among Persons Living with HIV/AIDS 
BioMed Research International  2014;2014:294963.
Objective. To evaluate the added value of QuantiFERON TB-Gold in-Tube (QTF-GIT) over the tuberculin skin testing (TST) for detecting latent tuberculosis (TB) infection (LTBI) among patients with AIDS in a city with a low TB incidence rate (11.1/100,000 inhabitants) and universal BCG coverage. Methods. Three hundred consecutive patients with AIDS in eight outpatient sexually transmitted disease public clinics in Brasilia were submitted to QFT-IT and TST between May 2011 and March 2013. A positive result of either test was considered to be LTBI. Results. Median CD4-cell count was 477.5 cells/mm3; 295 (98.3%) were using antiretroviral therapy. Eighteen patients (6%, 95% CI: 3.6%–9.3%) had LTBI, of whom 4 (1.3%, 95% CI: 0.04%–2.63%) had only a positive TST, 8 (2.7%, 95% CI: 0.8%–4.5%) had only a QFT-GIT positive test, and 6 (2%, 95% CI: 0.4%–3.6%) had positive results for both tests. This represents an 81.8% relative increase in LTBI detection when QFT-GIT is added to TST. The concordance between both tests was 96% (k = 0.48). Conclusions. The QFT-GIT alone was more effective to detect LTBI than TST alone and had an 81% added value as an add-on sequential test in this population with mild immunosuppression. The cost-effectiveness of these strategies remains to be evaluated.
PMCID: PMC4058839  PMID: 24991546
6.  The Significance of Sensitive Interferon Gamma Release Assays for Diagnosis of Latent Tuberculosis Infection in Patients Receiving Tumor Necrosis Factor-α Antagonist Therapy 
PLoS ONE  2015;10(10):e0141033.
We compared two interferon gamma release assays (IGRAs), QuantiFERON-TB Gold In-Tube (QFT-GIT) and T-SPOT.TB, for diagnosis of latent tuberculosis infection (LTBI) in patients before and while receiving tumor necrosis factor (TNF)-α antagonist therapy. This study evaluated the significance of sensitive IGRAs for LTBI screening and monitoring.
Before starting TNF-α antagonist therapy, 156 consecutive patients with rheumatic diseases were screened for LTBI using QFT-GIT and T-SPOT.TB tests. According to our study protocol, QFT-GIT-positive patients received LTBI treatment. Patients positive by any IGRAs were subjected to follow-up IGRA tests after completing LTBI-treatment and/or during TNF-α antagonist therapy.
At the initial LTBI screening, 45 (28.9%) and 70 (44.9%) patients were positive by QFT-GIT and T-SPOT.TB, respectively. The agreement rate between IGRA results was 78.8% (k = 0.56; 95% confidence interval [95% CI] = 0.43 to 0.68). Of 29 patients who were positive only by T-SPOT.TB in the initial screening, 83% (19/23) were persistently positive by T-SPOT.TB, while QFT-GIT testing showed that 36% (9/25) had conversion during TNF-α antagonist therapy. By the end of the follow-up period (218 to 1,264 days), four patients (4/137, 2.9%) developed active tuberculosis (TB) diseases during receiving TNF-α antagonist therapy. Among them, one was Q-T+, one was Q+T-, and the remaining two were Q-T- at the initial screening (Q, QuantiFERON-TB Gold In-Tube; T, T-SPOT.TB; +, positive; -, negative). Two (2/4, 50%) patients with TB reactivation had at least one prior risk factor consistent with previous TB infection.
This study demonstrated the need to capitalize on sensitive IGRAs to monitor for LTBI in at-risk patients for a more sensitive diagnosis in countries with an intermediate TB burden.
PMCID: PMC4608840  PMID: 26474294
7.  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 ▿ 
Clinical and Vaccine Immunology : CVI  2011;18(12):2102-2108.
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.
PMCID: PMC3232699  PMID: 21994356
8.  Deceleration during 'real life' motor vehicle collisions – a sensitive predictor for the risk of sustaining a cervical spine injury? 
The predictive value of trauma impact for the severity of whiplash injuries has mainly been investigated in sled- and crash-test studies. However, very little data exist for real-life accidents. Therefore, the predictive value of the trauma impact as assessed by the change in velocity of the car due to the collision (ΔV) for the resulting cervical spine injuries were investigated in 57 cases after real-life car accidents.
ΔV was determined for every car and clinical findings related to the cervical spine were assessed and classified according to the Quebec Task Force (QTF).
In our study, 32 (56%) subjects did not complain about symptoms and were therefore classified as QTF grade 0; 25 (44%) patients complained of neck pain: 8 (14%) were classified as QTF grade I, 6 (10%) as QTF grade II, and 11 (19%) as QTF grade IV. Only a slight correlation (r = 0.55) was found between the reported pain and ΔV. No relevant correlation was found between ΔV and the neck disability index (r = 0.46) and between ΔV and the QTF grade (r = 0.45) for any of the collision types. There was no ΔV threshold associated with acceptable sensitivity and specificity for the prognosis of a cervical spine injury.
The results of this study indicate that ΔV is not a conclusive predictor for cervical spine injury in real-life motor vehicle accidents. This is of importance for surgeons involved in medicolegal expertise jobs as well as patients who suffer from whiplash-associated disorders (WADs) after motor vehicle accidents.
Trial registration
The study complied with applicable German law and with the principles of the Helsinki Declaration and was approved by the institutional ethics commission.
PMCID: PMC2657117  PMID: 19267940
9.  Screening for latent tuberculosis in Norwegian health care workers: high frequency of discordant tuberculin skin test positive and interferon-gamma release assay negative results 
BMC Public Health  2013;13:353.
Tuberculosis (TB) presents globally a significant health problem and health care workers (HCW) are at increased risk of contracting TB infection. There is no diagnostic gold standard for latent TB infection (LTBI), but both blood based interferon-gamma release assays (IGRA) and the tuberculin skin test (TST) are used. According to the national guidelines, HCW who have been exposed for TB should be screened and offered preventive anti-TB chemotherapy, but the role of IGRA in HCW screening is still unclear.
A total of 387 HCW working in clinical and laboratory departments in three major hospitals in the Western region of Norway with possible exposure to TB were included in a cross-sectional study. The HCW were asked for risk factors for TB and tested with TST and the QuantiFERON®TB Gold In-Tube test (QFT). A logistic regression model analyzed the associations between risk factors for TB and positive QFT or TST.
A total of 13 (3.4%) demonstrated a persistent positive QFT, whereas 214 (55.3%) had a positive TST (≥ 6 mm) and 53 (13.7%) a TST ≥ 15 mm. Only ten (4.7%) of the HCW with a positive TST were QFT positive. Origin from a TB-endemic country was the only risk factor associated with a positive QFT (OR 14.13, 95% CI 1.37 - 145.38, p = 0.026), whereas there was no significant association between risk factors for TB and TST ≥ 15 mm. The five HCW with an initial positive QFT that retested negative all had low interferon-gamma (IFN-γ) responses below 0.70 IU/ml when first tested.
We demonstrate a low prevalence of LTBI in HCW working in hospitals with TB patients in our region. The “IGRA-only” seems like a desirable screening strategy despite its limitations in serial testing, due to the high numbers of discordant TST positive/IGRA negative results in HCW, probably caused by BCG vaccination or boosting due to repetitive TST testing. Thus, guidelines for TB screening in HCW should be updated in order to secure accurate diagnosis of LTBI and offer proper treatment and follow-up.
PMCID: PMC3637593  PMID: 23590619
Tuberculosis; Quantiferon; Interferon-gamma release assay; IGRA; Screening; Health care workers; Low-endemic country, Norway
10.  Contribution of Interferon gamma release assays testing to the diagnosis of latent tuberculosis infection in HIV-infected patients: A comparison of QuantiFERON-TB Gold In Tube, T-SPOT.TB and tuberculin skin test 
BMC Infectious Diseases  2012;12:169.
Diagnosis and treatment of latent tuberculosis infection (LTBI) is the most effective strategy to control tuberculosis (TB) among patients with HIV infection. The tuberculin skin test (TST) was the only available method to identify LTBI. The aim of the present work was to evaluate the usefulness of the interferon-gamma release assays (IGRAs): QuantiFERON-tuberculosis (TB) Gold-In-Tube test (QFG) and T-SPOT.TB for the diagnosis of LTBI in a diverse cohort of HIV-infected patients.
A prospective study was carried out in consecutive patients cared for in a single institution in Spain from January 2009 to October 2010. IGRAs and TST were performed simultaneously. TST induration ≥ 5 mm was considered positive.
QFG, T-SPOT.TB and TST were performed in 373 subjects. Median CD4 cell count was 470/μl with a median nadir of 150/μl. TST, QFG and T-SPOT.TB were positive in 13.3%, 7.5% and 18.5% cases respectively. Among 277 patients with neither past or current TB nor previous treatment for LTBI and who had TST results, a positive TST result was obtained in 20 (7.2%) cases. When adding QFG results to TST, there were a total of 26 (8.6%) diagnoses of LTBI. When the results of both IGRAs were added, the number of diagnoses increased to 54 (17.9%) (incremental difference: 10.7% [95% confidence interval [CI]:5.3-16.2%] [p < 0.001]), and when both IGRAs were added, the number of diagnoses reached 56 (18.5%) (incremental difference: 11.3% [95% CI:5.7%–16.9%] [p < 0.001]). Patients with a CD4 cell count greater than 500 cells/μl and prior stay in prison were more likely to have a diagnosis of LTBI by TST and/or QFG and/or T-SPOT.TB (adjusted odds ratio [aOR]: 3.8; 95% CI, 1.4 – 9.9; and aOR: 3.3; 95% CI, 1.3 – 8.3, respectively).
IGRAs were more sensitive than TST for diagnosis of M. tuberculosis infection in HIV-infected patients. Dual sequential testing with TST and IGRAs may be the optimal approach for LTBI screening in this population.
PMCID: PMC3482589  PMID: 22849726
11.  New tools for detecting latent tuberculosis infection: evaluation of RD1-specific long-term response 
Interferon-gamma (IFN-γ) release assays (IGRAs) were designed to detect latent tuberculosis infection (LTBI). However, discrepancies were found between the tuberculin skin test (TST) and IGRAs results that cannot be attributed to prior Bacille Calmètte Guerin vaccinations. The aim of this study was to evaluate tools for improving LTBI diagnosis by analyzing the IFN-γ response to RD1 proteins in prolonged (long-term response) whole blood tests in those subjects resulting negative to assays such as QuantiFERON-TB Gold In tube (QFT-IT).
The study population included 106 healthy TST+ individuals with suspected LTBI (recent contact of smear-positive TB and homeless) consecutively enrolled. As controls, 13 healthy subjects unexposed to M. tuberculosis (TST-, QFT-IT-) and 29 subjects with cured pulmonary TB were enrolled. IFN-γ whole blood response to RD1 proteins and QFT-IT were evaluated at day 1 post-culture. A prolonged test evaluating long-term IFN-γ response (7-day) to RD1 proteins in diluted whole blood was performed.
Among the enrolled TST+ subjects with suspected LTBI, 70/106 (66.0%) responded to QFT-IT and 64/106 (60.3%) to RD1 proteins at day 1. To evaluate whether a prolonged test could improve the detection of LTBI, we set up the test using cured TB patients (with a microbiologically diagnosed past pulmonary disease) who resulted QFT-IT-negative and healthy controls as comparator groups. Using this assay, a statistically significant difference was found between IFN-γ levels in cured TB patients compared to healthy controls (p < 0.006). Based on these data, we constructed a receiver operating characteristic (ROC) curve and we calculated a cut-off. Based on the cut-off value, we found that among the 36 enrolled TST+ subjects with suspected LTBI not responding to QFT-IT, a long term response to RD1 proteins was detected in 11 subjects (30.6%).
These results indicate that IFN-γ long-term response to M. tuberculosis RD1 antigens may be used to detect past infection with M. tuberculosis and may help to identify additional individuals with LTBI who resulted negative in the short-term tests. These data may provide useful information for improving immunodiagnostic tests for tuberculosis infection, especially in individuals at high risk for active TB.
PMCID: PMC2784468  PMID: 19930588
12.  Value of the tuberculin skin testing and of an interferon-gamma release assay in haemodialysis patients after exposure to M. tuberculosis 
BMC Infectious Diseases  2012;12:195.
Patients with end-stage renal disease (ESRD) and Mycobacterium tuberculosis infection pose a high risk of developing active TB disease. It is therefore important to detect latent TB infection (LTBI) to be able to offer treatment and prevent progression to TB disease. We assessed the value of the tuberculin skin test (TST) and of an interferon-gamma release assay (Quantiferon®-TB Gold in-Tube, QFT) for diagnosing LTBI in ESRD patients, after prolonged exposure to a highly contagious TB case in a haemodialysis unit. As a high number of patients presented erythema without induration in the TST response, this type of reaction was also analysed.
The TST and QFT were simultaneously performed twelve weeks after the last possible exposure to a bacilliferous TB patient. If the first TST (TST-1) was negative, a second TST (TST-2) was performed 15 days later to detect a booster response. A comparison was made between the TST responses (including those cases with erythema without induration) and those for the QFT. The correlation with risk of infection and the concordance between tests were both analysed.
A total of 52 patients fulfilled the inclusion criteria. Overall, 11 patients (21.2%) had a positive TST response: 3 for TST-1 and 8 for TST-2, and 18 patients (34.6%) showed a positive QFT response (p = 0.065). Erythema without induration was found in 3 patients at TST-1 and in a further 9 patients at TST-2. The three patients with erythema without induration in TST-1 had a positive TST-2 response. Concordance between TST and QFT was weak for TST-1 (κ = 0.21); it was moderate for overall TST (κ = 0.49); and it was strong if both induration and erythema (κ = 0.67) were considered.
In patients with ESRD, erythema without induration in the TST response could potentially be an indicator of M. tuberculosis infection. The QFT shows better accuracy for LTBI diagnosis than the TST.
PMCID: PMC3447656  PMID: 22905901
13.  Post-treatment change in Mycobacterium tuberculosis antigen-stimulated tumor necrosis factor-alpha release in patients with active tuberculosis 
Journal of Thoracic Disease  2015;7(5):903-907.
Monitoring tuberculosis (TB) treatment response remains challenging due to lack of reliable laboratory markers. In recent years, increased efforts have been exerted toward development of new biomarkers reflecting treatment response appropriately. While performance of interferon-gamma release assays (IGRAs) to monitor anti-TB treatment has been extensively evaluated, there is no data about post-treatment changes in Mycobacterium tuberculosis (MTB) antigen-stimulated tumor necrosis factor-alpha (TNF-α) release in active TB patients. Herein, we explored whether the MTB antigen-stimulated TNF-α release would be useful for monitoring responses to anti-TB treatment.
We compared unstimulated (TNF-αNil), MTB antigen-stimulated (TNF-αAg), and MTB antigen-stimulated minus unstimulated TNF-α levels (TNF-αAg-Nil) in supernatants from QuantiFERON-TB Gold In-Tube tests before and after treatment in 16 active TB patients, 25 latent TB infection (LTBI) subjects, and 10 healthy controls (HC).
TNF-αAg and TNF-αAg-Nil levels decreased significantly after treatment in patients with active TB. In addition, TNF-αNil, TNF-αAg, and TNF-αAg-Nil levels were significantly higher in untreated active TB patients compared to LTBI subjects and HC.
This finding cautiously suggests that MTB Ag-stimulated TNF-α response may be a potential adjunctive marker for monitoring treatment response in active TB patients.
PMCID: PMC4454850  PMID: 26101647
Tuberculosis (TB); tumor necrosis factor-alpha (TNF-α); treatment monitoring
14.  Evaluation of Interferon-Gamma Release Assays in the Diagnosis of Recent Tuberculosis Infection in Health Care Workers 
PLoS ONE  2009;4(8):e6686.
Health care workers (HCWs) are a group at risk of latent tuberculosis infection (LTBI). The aims of this study were to determine IFN-γ response by QuantiFERON-TB GOLD In Tube (QFN-G-IT) and T-SPOT.TB in HCWs, comparing the results with tuberculin skin test (TST); and to analyze the capacity of IFN-γ tests to detect recent versus remote LTBI with a prolonged stimulation test (PST).
Methodology/Principal Findings
A total of 147 HCWs were enrolled; 23 of whom were BCG vaccinated. 95 HCWs (64.6%) had a previous positive TST and were not retested; and 52 HCWs had a previous negative TST or were tested for the first time. When we analysed individuals without previous positive TST, the number of positive results for T-SPOT.TB was 12/52 (23.1%); and for QFN-G-IT, 9/52 (17.3%). The global concordance (κ) between T-SPOT.TB and QFN-G-IT with TST was 0.754 and 0.929 respectively. Of individuals with previous positive TST, T-SPOT.TB and QFN-G-IT were negative in 51.6% (49/95) and 62.1% (59/95) respectively, decreasing the concordance to 0.321 and 0.288, respectively. In non-BCG vaccinated HCWs with previous positive TST a positive IFN-γ test was associated with degree of exposure and diameter of TST. PST was performed in 24 HCW with previous positive TST and negative IFN-γ tests. PST was developed in 3 cell cultures stimulated with medium alone, ESAT-6 and CFP-10, respectively. In the third and sixth day of incubation period, part of the supernatants were replaced with complete medium supplemented with (rIL)-2. On day 9, ELISPOT assay was performed. In 14 samples PST was not valid due to not having enough cells. In 8 cases, the response was negative, and in 2 cases positive, suggesting that these patients were infected with Mycobacterium tuberculosis in some point in the past.
Both IFN-γ tests showed a similar number of positive results, and concordance between the tests was excellent. None of the tests was affected by prior BCG vaccination. IFN-γ tests are a useful tool for detecting recent infection in HCW population.
PMCID: PMC2726945  PMID: 19701460
15.  Tuberculosis contact investigation with a new, specific blood test in a low-incidence population containing a high proportion of BCG-vaccinated persons 
Respiratory Research  2006;7(1):77.
BCG-vaccination can confound tuberculin skin test (TST) reactions in the diagnosis of latent tuberculosis infection.
We compared the TST with a Mycobacterium tuberculosis specific whole blood interferon-gamma assay (QuantiFERON®-TB-Gold In Tube; QFT-G) during ongoing investigations among close contacts of sputum smear positive source cases in Hamburg, Germany.
During a 6-month period, 309 contacts (mean age 28.5 ± 10.5 years) from a total of 15 source cases underwent both TST and QFT-G testing. Of those, 157 (50.8%) had received BCG vaccination and 84 (27.2%) had migrated to Germany from a total of 25 different high prevalence countries (i.e. >20 cases/100,000). For the TST, the positive response rate was 44.3% (137/309), whilst only 31 (10%) showed a positive QFT-G result. The overall agreement between the TST and the QFT-G was low (κ = 0.2, with 95% CI 0.14.-0.23), and positive TST reactions were closely associated with prior BCG vaccination (OR 24.7; 95% CI 11.7–52.5). In contrast, there was good agreement between TST and QFT-G in non-vaccinated persons (κ = 0.58, with 95% CI 0.4–0.68), increasing to 0.68 (95% CI 0.46–0.81), if a 10-mm cut off for the TST was used instead of the standard 5 mm recommended in Germany.
The QFT-G assay was unaffected by BCG vaccination status, unlike the TST. In close contacts who were BCG-vaccinated, the QFT-G assay appeared to be a more specific indicator of latent tuberculosis infection than the TST, and similarly sensitive in unvaccinated contacts. In BCG-vaccinated close contacts, measurement of IFN-gamma responses of lymphocytes stimulated with M. tuberculosis-specific antigen should be recommended as a basis for the decision on whether to perform subsequent chest X-ray examinations or to start treatment for latent tuberculosis infection.
PMCID: PMC1481586  PMID: 16707012
16.  Therapy Recommendation “Act as Usual” in Patients with Whiplash Injuries QTF I° 
Up to now no therapy study has used the classification system of the Quebec Task Force (QTF) to differentiate between patients with (QTF II°) and without functional disorders (QTF I°). This differentiation seems meaningful, as this difference may be relevant for the correct treatment planning. In this context the effect of the therapy recommendation “act as usual” has been evaluated in a homogeneous patient collective with whiplash injuries QTF I°.
470 patients with acute whiplash injuries had been catched in this study and classified according to the QTF. 359 patients (76.4%) with QTF I° injuries could be identified. Out of that 162 patients were enrolled to the study and received the therapy recommendation “act as usual” and the adapted pain treatment with non-steroidal anti-inflammatory drugs (NSAID). After six months the outcome was evaluated by phone.
After injury the median pain score assessed by a visual analogue scale (VAS) was 5.4 (min = 3.3; max = 8.5). After six months 5 of the 162 patients complained intermittent pain symptoms (VAS values < 2). This is consistent with a chronification rate of 3.1%. After injury, the median pain disability index (PDI) was 3.9 (min = 1.9; max = 7.7). After six months 3 of the 162 patients stated persisting disability during sporting and physical activities (VAS values < 1).
The therapy recommendation “act as usual” in combination with an adapted pain treatment is sufficient. Usually patients with whiplash injuries QTF I° do not need physical therapy. An escalation of therapy measures should be reserved to patients with complicated healing processes.
PMCID: PMC4776986  PMID: 23121740
act as usual; therapy recommendation; whiplash injury; QTF classification
17.  Discrepancy between Mycobacterium tuberculosis-Specific Gamma Interferon Release Assays Using Short and Prolonged In Vitro Incubation▿  
The sensitivities of various gamma interferon release assays (IGRAs) for the detection of past latent Mycobacterium tuberculosis infection are not known. In this study, we aimed to assess the effects of various IGRA formats and in vitro incubation periods on test outcome. The results of the tuberculin skin test (TST) were compared with those of the QuantiFERON-TB Gold in-tube (QFT-GIT) test, an overnight enzyme-linked immunospot assay (ELISPOT), and a 6-day lymphocyte stimulation test (LST) by using the same M. tuberculosis-specific peptides and samples from 27 TST-positive persons with a history of exposure to M. tuberculosis, 4 patients cured of tuberculosis (TB), and 9 TST-negative controls. Among the TST-positive persons, the LST was more frequently positive (92%; P < 0.01) than either the QFT-GIT test (33%) or ELISPOT (46%). While good agreement was observed between the QFT-GIT test and ELISPOT (κ = 0.71) and between TST and LST (κ = 0.78), the agreement between TST or LST, on the one hand, and the QFT-GIT test or ELISPOT, on the other, was poor. These data indicate that the QFT-GIT test and overnight ELISPOT are less sensitive for the detection of past latent TB than the 6-day LST. The observed discrepancies between these IGRAs are most likely related to differences in incubation periods. Whether TST-positive persons with positive LST results but negative QFT-GIT and ELISPOT results are at risk for the development of TB needs to be elucidated before short-incubation IGRAs can be used for the screening of individuals for latent TB before immunosuppressive treatment.
PMCID: PMC1951056  PMID: 17507543
18.  Systematic Review: T-Cell–based Assays for the Diagnosis of Latent Tuberculosis Infection: An Update 
Annals of internal medicine  2008;149(3):177-184.
Interferon-γ–release assays (IGRAs) are alternatives to the tuberculin skin test (TST). A recent meta-analysis showed that IGRAs have high specificity, even among populations that have received bacille Calmette–Guérin (BCG) vaccination. Sensitivity was suboptimal for TST and IGRAs.
To incorporate newly reported evidence from 20 studies into an updated meta-analysis on the sensitivity and specificity of IGRAs.
Data Sources
PubMed was searched through 31 March 2008, and citations of all original articles, guidelines, and reviews for studies published in English were reviewed.
Study Selection
Studies that evaluated QuantiFERON-TB Gold, QuantiFERON-TB Gold In-Tube (both from Cellestis, Victoria, Australia), and T-SPOT.TB (Oxford Immunotec, Oxford, United Kingdom) or its precommercial ELISpot version, when data on the commercial version were lacking. For assessing sensitivity, the study sample had to have microbiologically confirmed active tuberculosis. For assessing specificity, the sample had to comprise healthy, low-risk individuals without known exposure to tuberculosis. Studies with fewer than 10 participants and those that included only immunocompromised participants were excluded.
Data Extraction
One reviewer abstracted data on participant characteristics, test characteristics, and test performance from 38 studies; these data were double-checked by a second reviewer. The original investigators were contacted for additional information when necessary.
Data Synthesis
A fixed-effects meta-analysis with correction for overdispersion was done to pool data within prespecified subgroups. The pooled sensitivity was 78% (95% CI, 73% to 82%) for QuantiFERON-TB Gold, 70% (CI, 63% to 78%) for QuantiFERON-TB Gold In-Tube, and 90% (CI, 86% to 93%) for T-SPOT.TB. The pooled specificity for both QuantiFERON tests was 99% among non–BCG-vaccinated participants (CI, 98% to 100%) and 96% (CI, 94% to 98%) among BCG-vaccinated participants. The pooled specificity of T-SPOT.TB (including its precommercial ELISpot version) was 93% (CI, 86% to 100%). Tuberculin skin test results were heterogeneous, but specificity in non–BCG-vaccinated participants was consistently high (97% [CI, 95% to 99%]).
Most studies were small and had limitations, including no gold standard for diagnosing latent tuberculosis and variable TST methods and cutoff values. Data on the specificity of the commercial T-SPOT.TB assay were limited.
The IGRAs, especially QuantiFERON-TB Gold and QuantiFERON-TB Gold In-Tube, have excellent specificity that is unaffected by BCG vaccination. Tuberculin skin test specificity is high in non–BCG-vaccinated populations but low and variable in BCG-vaccinated populations. Sensitivity of IGRAs and TST is not consistent across tests and populations, but T-SPOT.TB appears to be more sensitive than both QuantiFERON tests and TST.
PMCID: PMC2951987  PMID: 18593687 CAMSID: cams235
19.  Accuracy of Immunodiagnostic Tests for Active Tuberculosis Using Single and Combined Results: A Multicenter TBNET-Study 
PLoS ONE  2008;3(10):e3417.
The clinical application of IFN-γ release assays (IGRAs) has recently improved the diagnosis of latent tuberculosis infection. In a multicenter study of the Tuberculosis Network European Trialsgroup (TBNET) we aimed to ascertain in routine clinical practice the accuracy of a novel assay using selected peptides encoded in the mycobacterial genomic region of difference (RD) 1 for the diagnosis of active tuberculosis in comparison with tuberculin skin test (TST), QuantiFERON-TB GOLD In-Tube (Cellestis Ltd., Carnegie, Australia) and T-SPOT.TB (Oxfordimmunotec, Abingdon, UK).
Principal Findings
425 individuals from 6 different European centres were prospectively enrolled. We found that sensitivity of the novel test, TST, QuantiFERON-TB GOLD In-Tube and T-SPOT.TB was respectively 73.1%, 85.3%, 78.1%, and 85.2%; specificity was respectively 70.6%, 48.0%, 61.9% and 44.3%; positive likelihood ratios were respectively 2.48, 1.64, 2.05, and 1.53; negative likelihood ratios were respectively 0.38, 0.31, 0.35, 0.33. Sensitivity of TST combined with the novel test, QuantiFERON-TB GOLD In-Tube and T-SPOT.TB increased up to 92.4%, 97.7% and 97.1%, respectively. The likelihood ratios of combined negative results of TST with, respectively, the novel test, QuantiFERON-TB GOLD In-Tube and T-SPOT.TB were 0.19, 0.07 and 0.10.
The assay based on RD1 selected peptides has similar accuracy for active tuberculosis compared with TST and commercial IGRAs. Then, independently of the spectrum of antigens used in the assays to elicit mycobacterial specific immune responses, the novel test, IGRAs, and the TST do not allow an accurate identification of active tuberculosis in clinical practice. However, the combined use of the novel assay or commercial IGRAs with TST may allow exclusion of tuberculosis.
PMCID: PMC2561073  PMID: 18923709
20.  Influence of tumor necrosis factor α in rheumatoid arthritis  
Rheumatoid arthritis (RA) is the most prevalent inflammatory rheumatic disorder. It is a chronic and incurable disease that leads to painful inflammation, often irreversible joint damage, and eventually to functional loss.
Conventional treatment is based on unspecific immunosuppressive agents, e.g. Methotrexate, Azathioprin or Gold. However, the longterm outcomes of these approaches have been poor with frequently ongoing inflammatory disease activity, functional decline, and temporary or permanent work disability. More recently, antagonists of the human cytokine Tumor Necrosis Factor α (TNF-α) have been introduced that are potent suppressors of inflammatory processes. Infliximab is a chimeric antibody against TNF-α. Etanercept is a soluble human TNF-α receptor.
The report assesses the efficacy of TNF-α-antagonists to down-regulate inflammation, improve functional status and prevent joint damage in RA with particular regard to the following indications: Treatment of severe, refractory and ongoing disease activity despite adequate use of conventional antirheumatic agents; and treatment of early RA before conventional treatment failure has been demonstrated.
A systematic review of the literature is been performed using established electronic databases. The literature search is supplemented by a hand search of journals and publications relevant to RA, reviews of websites of national and international rheumatologic expert societies, as well as contacts to manufacturers. A priori defined inclusion and exclusion criteria are used for literature selection. Analysis and evaluation of included publications are based on standardised criteria sets and checklists of the German Scientific Working Group for Technology Assessment in Health Care.
Health Technology Assessment reports and metaanalyses cannot be identified. A total of 12 clinical trials are analysed, as well as national and international expert recommendations and practice guidelines. Numerous non-systematic reviews are found and analysed for additional sources of information that is not identified through the systematic search. Case reports and safety assessements are considered as well. A total of 137 publications is included.
The primary outcome measures in clinical trials are suppression of inflammatory disease activity and slowing of structural joint damage. Clinical response is usually measured by standardised response criteria that allow a semi-quantitative classification of improvement from baseline by 20%, 50%, or 70%.
In patients with RA refractory to conventional treatment, TNF-α-antagonists are unequivocally superior to Methotrexate with regard to disease activity, functional status and prevention of structural damage. In patients with early RA, TNF-α-antagonists show a more rapid onset of anti-inflammatory effects than Methotrexate. However, differences in clinical response rates and radiologic progression disappear after a few months of treatment and are no longer statistically significant. Serious adverse events are rare in clinical trials and do not occur significantly more often than in the control groups. However, case reports and surveillance registries show an increased risk for serious infectious complications, particularly tuberculosis. Expert panels recommend the use of TNF-α-antagonists in patients with active refractory RA after failure of conventional treatment. Studies that compare Infliximab and Etanercept are lacking.
There are no pharmacoeconomic studies although decision analytic models of TNF-α-antagonists for the treatment of RA exist. Based on the results of the models, a combination therapy with Hydroxychloroquin (HCQ), Sulfaslazin (SASP) and Methotrexate as well as Etanercept/Methotrexate can be considered a cost-effective treatment for Methotrexate-resistant RA.
TNF-α-antagonists are clearly effective in RA patients with no or incomplete response to Methotrexate and superior to continuous use of Methotrexate. It refers to both, reduction of inflammatory disease activity including pain relief and improved functional status, and prevention of structural joint damage. Therefore, TNF-α-antagonism is an important new approach in the treatment of RA. There is still insufficient evidence that early use of TNF-α-antagonists in RA prior to standard agents is beneficial and further studies have to be awaited.
An analytic model suggests that TNF-α-antagonists are, due to their clinical effectiveness in patients with no or incomplete response to Methotrexate, a cost-effective alternative to common therapies chosen in the subpopulations of patients. Nevertheless, it has to be borne in mind that the acquisition costs of TNF-α-antagonists lead to high incremental costs and C/E ratios, which exceed the common frame of assessing the cost-effectiveness of medical methods and technologies. Hence, society's willingness-to-pay is the critical determinant in the question whether TNF-α-antagonists shall be reimbursed or not, or to define criteria for reimbursement. Changes in the quality of life attributable to the use of TNF-α-antagonists in RA have not yet been assessed which might assist the decision making.
With respect of the questions mentioned above and the potential financial effect of a systematic use of TNF-α-antagonists in the treatment of RA, we come to the conclusion that TNF-α-antagonists should not introduced as a standard benefit reimbursed by the statutory health insurers in Germany.
PMCID: PMC3011313  PMID: 21289933
health economics; tumor necrosis factor; TNF-alpha; treatment; rheumatoid arthritis; cost-effectiveness
21.  Diagnosis of Active Tuberculosis in China Using an In-House Gamma Interferon Enzyme-Linked Immunospot Assay▿  
Gamma interferon (IFN-γ) release assays have been proven to be useful in the diagnosis of Mycobacterium tuberculosis infection. Nevertheless, their specificity and sensitivity vary among the different populations studied. Here, we evaluate the value of an in-house IFN-γ enzyme-linked immunospot (ELISPOT) assay in the diagnosis of active tuberculosis (TB) in Shenzhen, China, where the prevalence of tuberculosis is severe and Mycobacterium bovis BCG vaccination is mandatory at birth. A total of 305 patients with active tuberculosis, 18 patients with nontuberculosis lung diseases, and 202 healthy controls were recruited in this study. Among them, 156 individuals were simultaneously tested for IFN-γ responses by the commercial QuantiFERON-TB Gold in-tube (QFT-IT) assay. Tuberculin skin tests (TST) were performed with 202 healthy controls. The overall sensitivities of the ELISPOT and QFT-IT assays for active tuberculosis were 83.60% and 80.85%, respectively; the specificities were 76.6% and 73.26%, respectively. The IFN-γ ELISPOT responses, but not those of the TST, were significantly correlated with TB exposure (r = −0.6040, P < 0.0001). The sensitivities of the ELISPOT assay varied for patients with different forms of tuberculosis, with the highest sensitivity for patients with sputum-positive pulmonary tuberculosis (89.89%) and the lowest for those with tuberculous meningitis (62.5%). In conclusion, the IFN-γ ELISPOT assay is a useful adjunct to current tests for diagnosis of active TB in China. The ELISPOT assay is more accurate than TST in identifying TB infections.
PMCID: PMC2691059  PMID: 19339489
22.  Contribution of a heparin-binding haemagglutinin interferon-gamma release assay to the detection of Mycobacterium tuberculosis infection in HIV-infected patients: comparison with the tuberculin skin test and the QuantiFERON®-TB Gold In-tube 
The screening and treatment of latent tuberculosis (TB) infection reduces the risk of progression to active disease and is currently recommended for HIV-infected patients. The aim of this study is to evaluate, in a low TB incidence setting, the potential contribution of an interferon-gamma release assay in response to the mycobacterial latency antigen Heparin-Binding Haemagglutinin (HBHA-IGRA), to the detection of Mycobacterium tuberculosis infection in HIV-infected patients.
Treatment-naïve HIV-infected adults were recruited from 4 Brussels-based hospitals. Subjects underwent screening for latent TB using the HBHA-IGRA in parallel to a classical method consisting of medical history, chest X-ray, tuberculin skin test (TST) and QuantiFERON®-TB Gold In-Tube (QFT-GIT). Prospective clinical and biological follow-up ensued, with repeated testing with HBHA-IGRA. A group of HIV-infected patients with clinical suspicion of active TB was also recruited and tested with the HBHA-IGRA. Multiplex analysis was performed on the culture supernatants of this in-house assay to identify test read-outs alternative to interferon-gamma that could increase the sensitivity of the test.
Among 48 candidates enrolled for screening, 9 were identified with latent TB by TST and/or QFT-GIT results. Four of these 9 patients and an additional 3 screened positive with the HBHA-IGRA. This in-house assay identified all the patients that were positive for the TST and showed the best concordance with the presence of a M. tuberculosis exposure risk. During follow-up (median 14 months) no case of active TB was reported and HBHA-IGRA results remained globally constant. Fourteen HIV-infected patients with clinical suspicion of active TB were recruited. Active TB was confirmed for 6 of them among which 3 were HBHA-IGRA positive, each with very high interferon-gamma concentrations. All patients for whom active TB was finally excluded, including 2 non-tubercular mycobacterial infections, had negative HBHA-IGRA results. Multiplex analysis confirmed interferon-gamma as the best read-out.
The HBHA-IGRA appears complementary to the QuantiFERON®-TB Gold In-Tube for the screening of latent TB in HIV-infected patients. Large-scale studies are necessary to determine whether this combination offers sufficient sensitivity to dismiss TST, as suggested by our results. Furthermore, HBHA-IGRA may help in the diagnosis work-up of clinical suspicions of active TB.
PMCID: PMC4337251  PMID: 25886172
Active tuberculosis; Heparin-binding haemagglutinin; Human; Human immunodeficiency virus; Interferon-gamma release assay; Latent tuberculosis; Multiplex; Mycobacterium tuberculosis; QuantiFERON®-TB Gold In-Tube; Tuberculin skin test
23.  Discrimination between Active and Latent Tuberculosis Based on Ratio of Antigen-Specific to Mitogen-Induced IP-10 Production 
Journal of Clinical Microbiology  2014;53(2):504-510.
Mycobacterium tuberculosis is the major causative agent of tuberculosis (TB). The gamma interferon (IFN-γ) release assay (IGRA) has been widely used to diagnose TB by testing cell-mediated immune responses but has no capacity for distinguishing between active TB and latent TB infection (LTBI). This study aims to identify a parameter that will help to discriminate active TB and LTBI. Whole-blood samples from 33 active TB patients, 20 individuals with LTBI, and 26 non-TB controls were applied to the commercial IFN-γ release assay, QuantiFERON-TB Gold In-Tube, and plasma samples were analyzed for interleukin-2 (IL-2), IL-6, IL-8, IL-10, IL-13, tumor necrosis factor-alpha (TNF-α), IFN-γ, monokine induced by IFN-γ (MIG), interferon gamma inducible protein 10 (IP-10), interferon-inducible T cell alpha chemoattractant (I-TAC), and monocyte chemoattractant protein 1 (MCP-1) by using a commercial cytometric bead array. The Mycobacterium tuberculosis antigen-specific production of most of the assayed cytokines and chemokines was higher in the active TB than in the LTBI group. The mitogen-induced responses were lower in the active TB than in the LTBI group. When the ratio of TB-specific to mitogen-induced responses was calculated, IL-2, IL-6, IL-10, IL-13, TNF-α, IFN-γ, MIG, and IP-10 were more useful in discriminating active TB from LTBI. In particular, most patients showed higher IP-10 production to Mycobacterium tuberculosis antigens than to mitogen at the individual level, and the ratio for IP-10 was the strongest indicator of active infection versus LTBI with 93.9% sensitivity and 90% specificity. In conclusion, the ratio of the TB-specific to the mitogen-induced IP-10 responses showed the most promising accuracy for discriminating active TB versus LTBI and should be further studied to determine whether it can serve as a biomarker that might help clinicians administer appropriate treatments.
PMCID: PMC4298513  PMID: 25428147
24.  Role of Interferon Gamma Release Assay in Active TB Diagnosis among HIV Infected Individuals 
PLoS ONE  2009;4(5):e5718.
A rapid and specific test is urgently needed for tuberculosis (TB) diagnosis especially among human immunodeficiency virus (HIV) infected individuals. In this study, we assessed the sensitivity of Interferon gamma release assay (IGRA) in active tuberculosis patients who were positive for HIV infection and compared it with that of tuberculin skin test (TST).
Methodology/Principal Findings
A total of 105 HIV-TB patients who were naïve for anti tuberculosis and anti retroviral therapy were included for this study out of which 53 (50%) were culture positive. Of 105 tested, QuantiFERON-TB Gold in-tube (QFT-G) was positive in 65% (95% CI: 56% to 74%), negative in 18% (95% CI: 11% to 25%) and indeterminate in 17% (95% CI: 10% to 24%) of patients. The sensitivity of QFT-G remained similar in pulmonary TB and extra-pulmonary TB patients. The QFT-G positivity was not affected by low CD4 count, but it often gave indeterminate results especially in individuals with CD4 count <200 cells/µl. All of the QFT-G indeterminate patients whose sputum culture were positive, showed ≤0.25 IU/ml of IFN-γ response to phytohemagglutinin (PHA). TST was performed in all the 105 patients and yielded the sensitivity of 31% (95% CI: 40% to 22%). All the TST positives were QFT-G positives. The sensitivity of TST was decreased, when CD4 cell counts declined.
Our study shows neither QFT-G alone or in combination with TST can be used to exclude the suspicion of active TB disease. However, unlike TST, QFT-G yielded fewer false negative results even in individuals with low CD4 count. The low PHA cut-off point for indeterminate results suggested in this study (≤0.25 IU/ml) may improve the proportion of valid QFT-G results.
PMCID: PMC2685027  PMID: 19479058
25.  Comparison of interferon gamma release assay & tuberculin skin tests for diagnosis of latent tuberculosis in patients on maintenance haemodialysis 
Background & objectives:
Tuberculosis (TB) is a common infection in patients on haemodialysis. There is a definite role of treatment of latent TB (LTB) in these patients. However, diagnosis of LTB in these patients by tuberculin skin test (TST) is unreliable. There is suggestion that interferon gamma release assay (IGRA) will be more reliable test for diagnosis of LTB in this setting. Thus, we evaluated value of IGRA and TST for the diagnosis of LTB in patients on dialysis in an Indian setting.
Patients with end stage kidney disease on dialysis were included. Patients with active TB were excluded. Each patient was subjected to TST (induration of ≥10 mm was taken as positive) and QuantiFERON TB Gold In-Tube test (QFT-GIT) for diagnosis of LTB.
A total of 185 patients were included; 129 (69.7%) were males and mean age was 36.7 ± 12.3 yr. Past history of TB was present in 18 (9.7%) patients. One hundred and thirty four (72.4%) patients had scar of BCG vaccination. QFT-GIT test was positive in 66 (36%), TST in 32 (17%) and both in 13 (7%) patients. Of the 66 patients positive with QFT-GIT, only 13 (19.6%) were positive for TST. Of the 32 patients positive with TST, only 13 (40.6%) were positive with QFT-GIT; 100 (54%) patients were negative for both the tests. Overall, 85 (45.9%) patients were positive for either of the two tests. Poor agreement was shown between the two methods. On logistic regression analysis, odds of QFT-GIT to be positive in patients with BCG vaccination was 1.23 and with history of TB 0.99, both being insignificant. odds of tuberculin skin test to be positive in patients with BCG vaccination was 1.04 and with history of TB 0.99, both again being insignificant.
Interpretation & conclusions:
Our findings showed that more number of patients (36%) on haemodialysis were positive for QuantiFERON Gold In-Tube test as compared to TST (17%). There was poor agreement between the two tests. No significant effect of BCG vaccination and history of TB in past was observed on both tests.
PMCID: PMC4510727  PMID: 26112848
Haemodialysis; India; IGRA; latent tuberculosis; QuantiFERON; TB gold test; tuberculin test

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