The 'either test positive' strategy for latent tuberculous infection before anti-tumour necrosis factor treatment

Impact of Immunosuppressive Therapy on the Performance of Latent Tuberculosis Screening Tests in Patients with Inflammatory Bowel Disease: A Systematic Review and Meta-Analysis

Screening for latent tuberculosis infection (LTBI) is mandatory before commencing tumor necrosis factor (TNF)-α inhibitor use. However, the impact of immunosuppressive therapy (IST), including corticosteroids and immunomodulators, on the performance of LTBI screening in patients with inflammatory bowel disease (IBD) has not been fully elucidated. We searched all relevant studies published before November 2021 that examined the performance of interferon γ release assays (IGRAs) and tuberculin skin tests (TSTs) in patients with IBD who received IST, using the Medline, EMBASE, and Cochrane Library databases. We performed meta-analyses of positive or indeterminate rates of IGRA or TST according to IST and calculated the concordance rates between IGRA and TST results. A total of 20 studies with 4045 patients were included in the meta-analysis. The IGRA-positive rate was lower in patients on IST than in those not on IST (odds ratio (OR) (95% confidence interval (CI)) = 0.55 (0.39–0.78)), whereas the IGRA-indeterminate rate was higher in patients on IST than in those not on IST (OR (95% CI) = 2.91 (1.36–6.24)). The TST-positive rate did not differ between the on-IST and not-on-IST groups (OR (95% CI) = 0.87 (0.51–1.50)). The concordance rate between IGRA and TST was 83.3% (95% CI, 78.5–88.1%). The IGRA-negative/TST-positive rate tended to be higher than that the IGRA-positive/TST-negative rate (9.5% vs. 5.8%, respectively), although the difference was not statistically significant. In conclusion, IGRA results were negatively affected by IST in patients with IBD, supporting requirements that IGRA should be performed before initiating IST. The use of both an IGRA and TST in patients with IBD on IST may improve the diagnosis rate of LTBI.

ImmunoStart: preparing patients for immunosuppression

Objectives

Patients with immune-mediated inflammatory disease (IMID) present an increased risk of infection. Here, we present the concept of a preventive consultation called ImmunoStart and the first results of its implementation in the care pathway of patients with IMID.

Methods

Relevant information about vaccination history, tuberculosis exposure and other infectious risks were collected through blood sampling, complete anamnesis, chest X-ray and Mantoux test. During the ImmunoStart consultation, vaccination schedules, specific treatments and risk considerations were discussed.

Results

Between October 2016 and February 2020, 437 patients were seen at an ImmunoStart consultation, mainly referred by rheumatologists (56%), dermatologists (25%) and gastroenterologists (18%). A total of 421 (96%) patients needed at least one vaccine (a mean of 3.3 vaccines per patient). Live attenuated vaccine was indicated for 45 patients (10%), requiring them to reduce or interrupt their immunosuppressive drug(s). Ninety-two patients (21%) were treated for latent tuberculosis infection.

Conclusion

This preventive consultation provides a centralized and systematic setting for the direct management of patients with IMID in need of vaccination, treatment of latent disease and specific advice regarding their immunomodulating treatments.

Tuberculosis despite latent infection screening and treatment in patients receiving TNF inhibitor therapy

INTRODUCTION

Although latent tuberculosis infection (LTBI) treatment is given before anti-tumor necrosis factor (TNF) treatment, tuberculosis (TB) still develops in these patients and the risk factors are not well known. Besides, there is little data on the safety of isoniazid (INH) treatment in this group of patients. This study aimed to determine the risk factors for the development of tuberculosis and the safety of LTBI in such patients.

METHODS

All patients (n=665) given anti-TNF in a single center were included in this study. Complete data were obtained from the records of 389 patients.

RESULTS

Seven patients (1.1%) were diagnosed with TB. There was no significant difference in age, gender, smoking rate, comorbidities, leukocyte counts, hemoglobin, creatinine, AST, ALT, protein levels, and tuberculin reaction between patients with and without TB. Of 389 patients, 289 (76%) had received INH prophylaxis, including 43 tuberculin-negative patients. Thirty patients had anti-TNF use prior to INH prophylaxis. None of these patients had TB in the follow-up period. Seven patients who developed TB had completed LTBI treatment, including one patient who was tuberculin-negative. The time from the completion of INH treatment to the diagnosis of TB was 6-61 months. None had any history of contact with TB during this period. INH treatment was associated with hepatotoxicity in 49 patients (17%); all resolved without any need to stop INH.

CONCLUSION

Patients on anti-TNF treatment had a high rate of TB despite INH prophylaxis, but no risk factor for TB development was identified. Mild hepatotoxicity frequently developed during LTBI treatment. Key Points • Tuberculosis still develops in patients treated with tumor necrosis factor (TNF)-inhibitors despite prior screening and treatment for latent tuberculosis infection (LTBI). • In this cohort, all patients in whom tuberculosis developed had been treated for LTBI and all but one were initially tuberculin-positive. No risk factors have been identified. • The current policy of treating tuberculin-positive patients with a 9-month INH regimen does not seem to be fully effective in preventing tuberculosis.

Interferon-γ release assays or tuberculin skin test for detection and management of latent tuberculosis infection: a systematic review and meta-analysis

BACKGROUND

Use of an interferon-γ (IFN-γ) release assay or tuberculin skin test for detection and management of latent tuberculosis infection is controversial. For both types of test, we assessed their predictive value for the progression of latent infection to active tuberculosis disease, the targeting value of preventive treatment, and the necessity of dual testing.

METHODS

In this systematic review and meta-analysis, we searched PubMed, Embase, Web of Science, and the Cochrane Library, with no start date or language restrictions, on Oct 18, 2019, using the keywords ("latent tuberculosis" OR "latent tuberculosis infection" OR "LTBI") AND ("interferon gamma release assays" OR "Interferon-gamma Release Test" OR "IGRA" OR "QuantiFERON®-TB in tube" OR "QFT" OR "T-SPOT.TB") AND ("tuberculin skin test" OR "tuberculin test" OR "Mantoux test" OR "TST"). We included articles that used a cohort study design; included information that individuals with latent tuberculosis infection detected by IFN-γ release assay, tuberculin skin test, or both, progressed to active tuberculosis; reported information about treatment; and were limited to high-risk populations. We excluded studies that included patients with active or suspected tuberculosis at baseline, evaluated a non-commercial IFN-γ release assay, and had follow-up of less than 1 year. We extracted study details (study design, population investigated, tests used, follow-up period) and the number of individuals observed at baseline, who progressed to active tuberculosis, and who were treated. We then calculated the pooled risk ratio (RR) for disease progression, positive predictive value (PPV), and negative predictive value (NPV) of IFN-γ release assay versus tuberculin skin test.

FINDINGS

We identified 1823 potentially eligible studies after exclusion of duplicates, of which 256 were eligible for full-text screening. From this screening, 40 studies (50 592 individuals in 41 cohorts) were identified as eligible and included in our meta-analysis. Pooled RR for the rate of disease progression in untreated individuals who were positive by IFN-γ release assay versus those were negative was 9·35 (95% CI 6·48-13·49) compared with 4·24 (3·30-5·46) for tuberculin skin test. Pooled PPV for IFN-γ release assay was 4·5% (95% CI 3·3-5·8) compared with 2·3% (1·5-3·1) for tuberculin skin test. Pooled NPV for IFN-γ release assay was 99·7% (99·5-99·8) compared with 99·3% (99·0-99·5) for tuberculin skin test. Pooled RR for rates of disease progression in individuals positive by IFN-γ release assay who were untreated versus those who were treated was 3·09 (95% CI 2·08-4·60) compared with 1·11 (0·69-1·79) for the same populations who were positive by tuberculin skin test. Pooled proportion of disease progression for individuals who were positive by IFN-γ release assay and tuberculin skin test was 6·1 (95% CI 2·3-11·5). Pooled RR for rates of disease progression in individuals who were positive by IFN-γ release assay and tuberculin skin test who were untreated versus those who were treated was 7·84 (95% CI 4·44-13·83).

INTERPRETATION

IFN-γ release assays have a better predictive ability than tuberculin skin tests. Individuals who are positive by IFN-γ release assay might benefit from preventive treatment, but those who are positive by tuberculin skin test probably will not. Dual testing might improve detection, but further confirmation is needed.

FUNDING

National Natural Science Foundation of China and Natural Foundation of Yunnan Province.

Tuberculosis and Biologic Therapies: Anti-Tumor Necrosis Factor-α and Beyond

Biologic drugs have revolutionized the treatment of certain hematologic, autoimmune, and malignant diseases, but they may place patients at risk for reactivation or acquisition of tuberculosis. This risk is highest with the tumor necrosis factor-alpha (TNF-α) inhibitors. Amongst this class of drugs, the monoclonal antibodies (infliximab, adalimumab, golimumab) and antibody fragment (certolizumab) carry an increased risk compared to the soluble receptor fusion molecule, etanercept. Treatment of latent TB is critical to decrease the risk of reactivation. Data continues to emerge regarding tuberculosis risk associated with novel biologics targeting cytokines involved in tuberculosis control.

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

BACKGROUND

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

OBJECTIVES

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

DESIGN

A prospective cohort study and economic analysis.

PARTICIPANTS AND SETTING

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

MAIN OUTCOME MEASURES

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

RESULTS

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

CONCLUSION

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

IMPLICATIONS FOR PRACTICE AND FUTURE RESEARCH

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

STUDY REGISTRATION

This study is registered as NCT01162265.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Incidence of Active Tuberculosis within One Year after Tumor Necrosis Factor Inhibitor Treatment according to Latent Tuberculosis Infection Status in Patients with Inflammatory Bowel Disease

BACKGROUND

We investigated the incidence of active tuberculosis among patients with inflammatory bowel disease (IBD) treated with tumor necrosis factor (TNF) inhibitors, with or without latent tuberculosis infection (LTBI).

METHODS

The study was performed at a Korean tertiary referral center between January 2011 and June 2017. In total, 740 patients with IBD who underwent LTBI screening tests and were followed-up for ≥ 1 year after TNF inhibitor treatment initiation were enrolled. LTBI was detected on the basis of tuberculin skin test results, interferon-gamma release assay results, chest X-ray findings, and previous tuberculosis treatment history. The patients were classified into LTBI (n = 84) or non-LTBI (n = 656) group. The risk of developing tuberculosis in each group was assessed on the basis of standardized incidence ratio (SIR) and 95% confidence interval (CI) for active tuberculosis.

RESULTS

Mean patient age was 33.1 years, and patients with Crohn's disease were predominant (80.7%). Within 1 year after the initiation of TNF inhibitor treatment, 1 patient in the LTBI group (1/84; 1.2%) and 7 patients in the non-LTBI group (7/656; 1.1%) developed active tuberculosis. The overall 1-year incidence of tuberculosis among the patients was significantly higher than that among the general population (SIR, 14.0; 95% CI, 7.0-28.0), and SIR was not affected by LTBI status (LTBI group: 14.5, 95% CI, 2.0-102.6; non-LTBI group: 14.0, 95% CI, 6.7-29.4).

CONCLUSION

Patients with IBD undergoing TNF inhibitor treatment showed a higher 1-year incidence of tuberculosis than the general population irrespective of LTBI status.

The usefulness of routine chest radiograph examinations in patients treated with TNF inhibitors for inflammatory arthritis in South Korea

OBJECTIVES

We aimed to investigate the usefulness of routine chest radiograph (CXR) examinations for patients with inflammatory arthritis treated with a tumor necrosis factor (TNF) inhibitor in terms of (i) the role of CXR in baseline latent tuberculosis infection (LTBI) screening and (ii) detecting asymptomatic active tuberculosis after TNF inhibitor initiation.

METHODS

From January 2011 to June 2017, 469 patients with inflammatory arthritis were enrolled in the study at a tertiary referral center in South Korea. At our institution, CXR was performed for all patients undergoing a tuberculin skin test (TST) and/or an interferon-gamma release assay (IGRA) at the LTBI screening visit. LTBI treatment was determined by (i) positive TST or IGRA or (ii) CXR findings suggestive of spontaneously healed tuberculosis. After TNF inhibitor initiation, patients were recommended to undergo CXR at a specified interval.

RESULTS

Of 469 patients, 187 were treated for LTBI. Among them, 181 patients were treated for LTBI because of a positive TST or IGRA result. TST was considered positive if induration size was ≥10 mm. The remaining six patients were considered positive on the basis of CXR findings compatible with spontaneously healed tuberculosis, such as noncalcified nodules with distinct margins and fibrotic linear opacity, despite demonstrating negative results for TST and IGRA. Thus, CXR had a diagnostic value as a baseline LTBI test in 6 (1.3%) patients. After TNF inhibitor initiation, 2 patients who had respiratory symptoms were diagnosed with active tuberculosis. For asymptomatic patients, routine CXR follow-up could not detect any case of active pulmonary tuberculosis within 1 year (n = 219) or after 1 year (n = 217).

CONCLUSIONS

CXR should be performed as one of the LTBI screening tests for patients with inflammatory arthritis in a tuberculosis-prevalent country. However, after TNF inhibitor treatment, routine CXR follow-up was not advantageous.

Asian Organization for Crohn's and Colitis and Asia Pacific Association of Gastroenterology consensus on tuberculosis infection in patients with inflammatory bowel disease receiving anti-tumor necrosis factor treatment. Part 1: risk assessment

Because anti-tumor necrosis factor (anti-TNF) therapy has become increasingly popular in many Asian countries, the risk of developing active tuberculosis (TB) among anti-TNF users may raise serious health problems in this region. Thus, the Asian Organization for Crohn's and Colitis and the Asia Pacific Association of Gastroenterology have developed a set of consensus statements about risk assessment, detection and prevention of latent TB infection, and management of active TB infection in patients with inflammatory bowel disease (IBD) receiving anti-TNF treatment. Twenty-three consensus statements were initially drafted and then discussed by the committee members. The quality of evidence and the strength of recommendations were assessed by using the Grading of Recommendations Assessment, Development, and Evaluation methodology. Web-based consensus voting was performed by 211 IBD specialists from 9 Asian countries concerning each statement. A consensus statement was accepted if at least 75% of the participants agreed. Part 1 of the statements comprised 2 parts: risk of TB infection Recommendaduring anti-TNF therapy, and screening for TB infection prior to commencing anti-TNF therapy. These consensus statements will help clinicians optimize patient outcomes by reducing the morbidity and mortality related to TB infections in patients with IBD receiving anti-TNF treatment.

Asian Organization for Crohn's and Colitis and Asian Pacific Association of Gastroenterology consensus on tuberculosis infection in patients with inflammatory bowel disease receiving anti-tumor necrosis factor treatment. Part 1: Risk assessment

Because anti-tumor necrosis factor (anti-TNF) therapy has become increasingly popular in many Asian countries, the risk of developing active tuberculosis (TB) among anti-TNF users may raise serious health problems in this region. Thus, the Asian Organization for Crohn's and Colitis and the Asian Pacific Association of Gastroenterology have developed a set of consensus statements about risk assessment, detection, and prevention of latent TB infection and management of active TB infection in patients with inflammatory bowel disease (IBD) receiving anti-TNF treatment. Twenty-three consensus statements were initially drafted and then discussed by the committee members. The quality of evidence and the strength of recommendations were assessed by using the Grading of Recommendations Assessment, Development, and Evaluation methodology. Web-based consensus voting was performed by 211 IBD specialists from nine Asian countries concerning each statement. A consensus statement was accepted if at least 75% of the participants agreed. Part 1 of the statements comprised two parts: (i) risk of TB infection during anti-TNF therapy and (ii) screening for TB infection prior to commencing anti-TNF therapy. These consensus statements will help clinicians optimize patient outcomes by reducing the morbidity and mortality related to TB infections in patients with IBD receiving anti-TNF treatment.

Biologic Agents and Tuberculosis

Treatment with biologic agents, in particular tumor necrosis factor alpha (TNF-α) inhibitors, is associated with an increased risk of tuberculosis (TB), and screening and treatment for latent TB infection (LTBI) in patients undergoing such treatment is therefore indicated. The risk of TB associated with different biologics varies significantly, with the highest relative risks, 29.3 and 18.6, associated with adalimumab and infliximab, respectively. The risk of TB with newer TNF-α inhibitors and other biologics appears to be lower. Performance of LTBI screening tests is affected by immune-mediated inflammatory diseases and immunosuppressive therapy in patients due to commence TNF-α inhibitor treatment. Interferon gamma release assays (IGRAs) have a higher specificity than the tuberculin skin test (TST) in patients with Bacillus Calmette–Guérin (BCG) vaccination and have probably a better sensitivity than TST in immunosuppressed patients. LTBI screening programs prior to commencement of anti-TNF-α treatment significantly reduce the incidence of TB, but the optimal screening algorithm, in particular the question of whether a combination of IGRA and TST or a single test only should be used, is a matter of ongoing debate. Use of TST in combination with IGRA is justified to increase sensitivity. Repeat testing for LTBI should be limited to patients at increased risk of TB. If TB develops during anti-TNF-α treatment, it is more likely to be disseminated and extrapulmonary than are other TB cases. Discontinuation of anti-TNF-α treatment in patients diagnosed with TB is associated with an increased risk of immune reconstitution inflammatory syndrome, which is probably best managed by reintroduction of anti-TNF-α treatment.

The tuberculin skin test still matters for the screening of latent Tuberculosis infections among Inflammatory Bowel Disease patients

BACKGROUND AND AIMS

There is a high risk of Tuberculosis among patients medicated with anti-tumour necrosis factor α (anti-TNFα) that can be mitigated by treating latent Tuberculosis infections (LTI). This study aimed to evaluate the performance of Tuberculin Skin test (TST) and Quantiferon-TB Gold in Tube (QFT-GIT) in a population of patients suffering from Inflammatory Bowel Diseases.

METHODS

The cohort analyzed in this study consisted of 250 patients, of whom 15% were therapy-naïve and 85% were medicated: 70% under immunosuppressive therapy and 30% on anti-TNFα. A LTBI was diagnosed following a positive result in either of the tests and their performance and concordance were evaluated.

RESULTS

Fifty-eight and 24 patients had a positive TST and QFT-GIT, respectively. In 72 (29%) patients LTBI was diagnosed, of whom 8 (21%) were therapy-naïve. TST had an overall higher sensitivity (81% vs. 35%) and a higher Negative Predictive Value (93% vs. 80%) when compared to QFT-GIT test; this superiority was consistently maintained irrespective of the presence and kind of backbone immunosuppressive therapies. The concordance between both tests was weak.

CONCLUSIONS

Our results underscore the need to maintain the TST on LTBI diagnosis in patients about to start or switch anti-TNFα therapy in an intermediate Tuberculosis incidence context.

Tuberculosis in Anti-Tumour Necrosis Factor-treated Inflammatory Bowel Disease Patients After the Implementation of Preventive Measures: Compliance With Recommendations and Safety of Retreatment

BACKGROUND AND AIMS

Despite having adopted preventive measures, tuberculosis (TB) may still occur in patients with inflammatory bowel disease (IBD) treated with anti-tumour necrosis factor (anti-TNF). Data on the causes and characteristics of TB cases in this scenario are lacking. Our aim was to describe the characteristics of TB in anti-TNF-treated IBD patients after the publication of the Spanish TB prevention guidelines in IBD patients and to evaluate the safety of restarting anti-TNF after a TB diagnosis.

METHODS

In this multicentre, retrospective, descriptive study, TB cases from Spanish hospitals were collected. Continuous variables were reported as mean and standard deviation or median and interquartile range. Categorical variables were described as absolute and relative frequencies and their confidence intervals when necessary.

RESULTS

We collected 50 TB cases in anti-TNF-treated IBD patients, 60% male, median age 37.3 years (interquartile range [IQR] 30.4-47). Median latency between anti-TNF initiation and first TB symptoms was 155.5 days (IQR 88-301); 34% of TB cases were disseminated and 26% extrapulmonary. In 30 patients (60%), TB cases developed despite compliance with recommended preventive measures; *not performing 2-step TST (tuberculin skin test) was the main failure in compliance with recommendations. In 17 patients (34%) anti-TNF was restarted after a median of 13 months (IQR 7.1-17.3) and there were no cases of TB reactivation.

CONCLUSIONS

Tuberculosis could still occur in anti-TNF-treated IBD patients despite compliance with recommended preventive measures. A significant number of cases developed when these recommendations were not followed. Restarting anti-TNF treatment in these patients seems to be safe.

Adequacy of initiating TNF antagonists within 3 weeks of starting latent tuberculosis infection treatment in patients with immune-mediated inflammatory diseases

Background This study investigated whether tumour necrosis factor (TNF) antagonists should be initiated within 3 weeks of latent tuberculosis infection (LTBI) treatment in patients with immune-mediated inflammatory disease (IMID). Methods Between June 2004 and October 2013, a total of 1521 IMID patients were screened for LTBI before initiating anti-TNF therapy at a tertiary referral centre in South Korea. Their medical records were retrospectively reviewed. Results A total of 411 patients received LTBI treatment before receiving TNF antagonists between June 2004 and October 2013. The mean age of the 411 study subjects was 44.5 years and 261 (63.5%) were male. Anti-TNF agent was initiated in 61 patients (14.8%) within 3 weeks after chemoprophylaxis for LTBI, but 3 weeks later in the remaining 350 patients (85.2%). These two groups were comparable in terms of baseline characteristics, but differed significantly in the mean duration of LTBI treatment before commencing anti-TNF therapy (8 vs 30 days, p < 0.001). A total of six patients developed TB during the follow-up period and received anti-TNF agents 3 weeks after initiation of LTBI treatment. None of the patients who commenced TNF antagonist therapy within 3 weeks of LTBI treatment developed TB. Conclusions TNF antagonists may be initiated within 3 weeks of commencing LTBI treatment in IMID patients.

Factors that Predict Negative Results of QuantiFERON-TB Gold In-Tube Test in Patients with Culture-Confirmed Tuberculosis: A Multicenter Retrospective Cohort Study

BACKGROUND

Interferon-γ release assays such as the QuantiFERON-TB Gold In-Tube Test (QFT-GIT) are designed to detect Mycobacterium tuberculosis infections, whether latent or manifesting as disease. However, a substantial number of persons with culture-confirmed tuberculosis (TB) have negative QFT-GITs. Information on host factors contributing to false-negative and indeterminate results are limited.

METHODS

A multicenter retrospective cohort study was performed with 1,264 culture-confirmed TB patients older than 18 years who were subjected to the QFT-GIT at one of the six hospitals between May 2007 and February 2014. Patients with human immunodeficiency virus infection were excluded. Clinical and laboratory data were collected in South Korea.

RESULTS

Of all patients, 87.6% (1,107/1,264) were diagnosed with pulmonary TB and 12.4% (157/1,264) with extrapulmonary TB. The rate of negative results was 14.4% (182/1,264). The following factors were highly correlated with false-negative results in the QFT-GIT: advanced age (age ≥ 65 years, odds ratio [OR] 1.57, 95% confidence interval [CI] 1.03-2.39), bilateral disease as determined by chest radiography (OR 1.75, 95% CI 1.13-2.72), malignancy (OR 2.42, 95% CI 1.30-4.49), and lymphocytopenia (total lymphocyte count < 1.0 × 109/L, OR 1.86, 95% CI 1.21-2.87).

CONCLUSIONS

Consequently, QFT-GIT results need to be interpreted with caution in patients with these host risk factors such as the elderly, bilateral disease on chest radiography, or malignancy, or lymphocytopenia.

Diagnosis and treatment of latent tuberculosis infection

A small number of viable tuberculosis bacilli can reside in an individual with latent tuberculosis infection (LTBI) without obvious clinical symptoms or abnormal chest radiographs. Diagnosis and treatment for LTBI are important for tuberculosis (TB) control in public and private health, especially in high-risk populations. The updated 2014 Korean guidelines for TB recommend that tuberculin skin tests, interferon-gamma release assays, or a combination of the two can be used for LTBI diagnosis according to age and immune status of the host as well as TB contact history. The regimens for LTBI treatment include isoniazid, rifampicin, or isoniazid/rifampicin. However, results of drug susceptibility test from the index case must be considered in selecting the appropriate drug for recent contacts. Standardized LTBI diagnosis and treatment based on the new 2014 guidelines will contribute to the effective TB control in Korea as well as to the establishment of updated guidelines.

QuantiFERON-TB Gold In-Tube assay for screening arthritis patients for latent tuberculosis infection before starting anti-tumor necrosis factor treatment

Background

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.

Methods

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.

Results

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).

Conclusion

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.

Diagnosis of latent tuberculosis infection before initiation of anti-tumor necrosis factor therapy using both tuberculin skin test and QuantiFERON-TB Gold In Tube assay

BACKGROUND

Reactivation of latent tuberculosis infection (LTBI) is an important complication in patients treated with tumor necrosis factor-alpha (TNF-α) blocking agents. However, the best method for LTBI detection before initiation of anti-TNF therapy remains to be determined.

METHODS

From January 2010 to August 2013, anti-TNF therapy was initiated in 426 patients with immune-mediated inflammatory diseases (IMIDs). Tuberculin skin test (TST) and Quantiferon-TB Gold In Tube (QFT-GIT) assay were performed before starting anti-TNF treatment. LTBI was defined as a positive TST (induration ≥ 10 mm) or as a positive QFT-GIT result. Patients were followed up until December 2013.

RESULTS

The positive TST and QFT-GIT rates were 22.3% (95/426) and 16.0% (68/426), respectively, yielding a total of 27.0% (115/426) of positive LTBI results. LTBI treatment was initiated in 25.1% (107/426) and was completed in 100% (107/107) of patients. During a median 294 days of follow-up, active TB occurred in 1.4% (6/426) of the patients with negative TST and QFT-GIT results at baseline.

CONCLUSION

The either test positive strategy, using both TST and QFT-GIT assay, is acceptable for LTBI screening before commencing anti-TNF therapy in patients with IMIDs.