Tuberculosis screening using IGRA and chest computed tomography in patients with inflammatory bowel disease: A retrospective study

CT in the detection of latent tuberculosis: a systematic review

AIM

To evaluate the use of computed tomography (CT) and low-dose CT in the detection of latent tuberculosis (TB).

MATERIALS AND METHODS

A systematic search of literature in adherence with the PRISMA guidelines was carried out. Quality assessment of the included studies was conducted.

RESULTS

The search strategy identified a total of 4,621 studies. Sixteen studies were considered eligible and included in the review. There was high heterogeneity among all studies. CT was identified as much more sensitive for the detection of latent TB in all studies despite chest radiography often being recommended in guidelines to assess patients for latent TB. Low-dose CT showed promising results in four of the studies; however, these results were limited due to small sample sizes.

CONCLUSION

CT is much superior to chest radiography consistently identifying additional cases of latent TB. There are limited high-quality publications available using low-dose CT but findings thus far suggest low-dose CT could be used as an alternative to standard-dose CT for the detection of latent TB. It is recommended that a randomised controlled trial investigating low-dose CT should be carried out.

Review article: latent tuberculosis in patients with inflammatory bowel diseases receiving immunosuppression-risks, screening, diagnosis and management

BACKGROUND

One quarter of the world's population has latent tuberculosis infection (LTBI). Systemic immunosuppression is a risk factor for LTBI reactivation and the development of active tuberculosis. Such reactivation carries a risk of significant morbidity and mortality. Despite the increasing global incidence of inflammatory bowel disease (IBD) and the use of immune-based therapies, current guidelines on the testing and treatment of LTBI in patients with IBD are haphazard with a paucity of evidence.

AIM

To review the screening, diagnostic practices and medical management of LTBI in patients with IBD.

METHODS

Published literature was reviewed, and recommendations for testing and treatment were synthesised by experts in both infectious diseases and IBD.

RESULTS

Screening for LTBI should be performed proactively and includes assessment of risk factors, an interferon-gamma releasing assay or tuberculin skin test and chest X-ray. LTBI treatment in patients with IBD is scenario-dependent, related to geographical endemicity, travel and other factors. Ideally, LTBI therapy should be used prior to immune suppression but can be applied concurrently where urgent IBD medical treatment is required. Management is best directed by a multidisciplinary team involving gastroenterologists, infectious diseases specialists and pharmacists. Ongoing surveillance is recommended during therapy. Newer LTBI therapies show promise, but medication interactions need to be considered. There are major gaps in evidence, particularly with specific newer therapeutic approaches to IBD.

CONCLUSIONS

Proactive screening for LTBI is essential in patients with IBD undergoing immune-suppressing therapy and several therapeutic strategies are available. Reporting of real-world experience is essential to refining current management recommendations.

Stringent screening strategy significantly reduces reactivation rates of tuberculosis in patients with inflammatory bowel disease on anti-TNF therapy in tuberculosis endemic region

BACKGROUND

Anti-tumor necrosis factor (anti-TNF) therapy use in patients with inflammatory bowel disease (IBD) leads to an increased risk of tuberculosis (TB) reactivation despite latent tuberculosis (LTB) screening, especially in TB endemic regions.

AIM

We evaluated the effect of stringent screening strategy and LTB prophylaxis on TB reactivation.

METHODS

We performed an ambispective comparison between patients who received anti-TNF therapy after January 2019 (late cohort) and between Jan 2005 and Jan 2019 (early cohort). Late cohort patients were subjected to stringent screening criteria which included all: history of past TB/recent contact with active TB, chest X-ray, CT (computed tomography) chest, IGRA (interferon-gamma release assay), TST (tuberculin skin test), and if any positive were given chemoprophylaxis. A cohort comparison was done to evaluate for risk reduction of TB following the stringent screening strategy.

RESULTS

One hundred seventy-one patients (63: ulcerative colitis/108: Crohn's disease, mean age diagnosis: 28.5 ± 13.4 years, 60% males, median follow-up duration after anti-TNF: 33 months [interquartile range: 23-57 months]) were included. Among the 112 in the early cohort, 29 (26%) underwent complete TB screening, 22 (19.6%) had LTB, 10 (9%) received chemoprophylaxis, and 19 (17%) developed TB. In comparison, in the late cohort, 100% of patients underwent complete TB screening, 26 (44%) had LTB, 23 (39%) received chemoprophylaxis, and only 1(1.7%) developed TB (p < 0.01). On survival analysis, patients in early cohort had a higher probability of TB reactivation compared with the late cohort (HR: 14.52 (95% CI: 1.90-110.61 [p = 0.01]) after adjusting for gender, age at anti-TNF initiation, concomitant immunosuppression, anti-TNF doses, and therapy escalation.

CONCLUSION

The high risk of TB reactivation with anti-TNF therapy in TB endemic regions can be significantly mitigated with stringent LTB screening and chemoprophylaxis.

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.

A Histogram-Based Low-Complexity Approach for the Effective Detection of COVID-19 Disease from CT and X-ray Images

The global COVID-19 pandemic certainly has posed one of the more difficult challenges for researchers in the current century. The development of an automatic diagnostic tool, able to detect the disease in its early stage, could undoubtedly offer a great advantage to the battle against the pandemic. In this regard, most of the research efforts have been focused on the application of Deep Learning (DL) techniques to chest images, including traditional chest X-rays (CXRs) and Computed Tomography (CT) scans. Although these approaches have demonstrated their effectiveness in detecting the COVID-19 disease, they are of huge computational complexity and require large datasets for training. In addition, there may not exist a large amount of COVID-19 CXRs and CT scans available to researchers. To this end, in this paper, we propose an approach based on the evaluation of the histogram from a common class of images that is considered as the target. A suitable inter-histogram distance measures how this target histogram is far from the histogram evaluated on a test image: if this distance is greater than a threshold, the test image is labeled as anomaly, i.e., the scan belongs to a patient affected by COVID-19 disease. Extensive experimental results and comparisons with some benchmark state-of-the-art methods support the effectiveness of the developed approach, as well as demonstrate that, at least when the images of the considered datasets are homogeneous enough (i.e., a few outliers are present), it is not really needed to resort to complex-to-implement DL techniques, in order to attain an effective detection of the COVID-19 disease. Despite the simplicity of the proposed approach, all the considered metrics (i.e., accuracy, precision, recall, and F-measure) attain a value of 1.0 under the selected datasets, a result comparable to the corresponding state-of-the-art DNN approaches, but with a remarkable computational simplicity.

Asian Organization for Crohn's and Colitis and Asia Pacific Association of Gastroenterology practice recommendations for medical management and monitoring of inflammatory bowel disease in Asia

Inflammatory bowel disease (IBD) has increased in incidence and prevalence in Asian countries since the end of the 20th century. Moreover, differences in the cause, phenotypes, and natural history of IBD between the East and West have been recognized. Therefore, the Asian Organization for Crohn's and Colitis and the Asia Pacific Association of Gastroenterology have established recommendations on medical management of IBD in Asia. Initially, the committee members drafted 40 recommendations, which were then assessed according to Grading of Recommendations Assessment, Development and Evaluation. Eight statements were rejected as this indicated that consensus had not been reached. The recommendations encompass pretreatment evaluation; medical management of active IBD; medical management of IBD in remission; management of IBD during the periconception period and pregnancy; surveillance strategies for colitis-associated cancer; monitoring side effects of thiopurines and methotrexate; and infections in IBD.

Chest Radiographs and CT Findings during Healthcare Workers' Tuberculosis Screening Using Interferon-Gamma Release Assay: Retrospective Observational Study

Purpose

To investigate the incidence of tuberculosis (TB) in healthcare workers (HCWs) with positive interferon-gamma release assay (IGRA) results based on chest X-ray (CXR) and CT findings and determine the role of imaging in the diagnosis of TB.

Materials and Methods

Among 1976 hospital personnel screened for TB using IGRA, IGRA-positive subjects were retrospectively investigated. Clustered nodular and/or linear streaky opacities in the upper lung zone were considered positive on CXR. The CT findings were classified as active, indeterminate, inactive, or normal. The active or indeterminate class was considered CT-positive.

Results

IGRA was positive in 255 subjects (12.9%). CXR and CT were performed in 249 (99.2%) and 113 subjects (45.0%), respectively. CXR- and CT-positive findings were found in 7 of 249 (2.8%) and 9 of 113 (8.0%) patients, respectively. Among the nine CT-positive subjects, active and indeterminate TB findings were found in 6 (5.3%) and 3 (2.7%) patients, respectively. Microbiological tests, including acid-fast bacilli staining, culture, and polymerase chain reaction for TB, were negative in all nine CT-positive subjects. Empirical anti-TB medications were administered to 9 CT-positive subjects, and 3 of these nine subjects were CXR-negative for pulmonary TB.

Conclusion

CT helped diagnose asymptomatic TB in IGRA-positive HCWs.

TST conversions and systemic interferon-gamma increase after methotrexate introduction in psoriasis patients

Background

Tuberculosis screening in psoriasis patients is complex due to the immunological alterations associated with psoriasis, the presence of comorbidities, and the effect of immunosuppressive treatment. However, it is not established whether the results of screening tests are affected by these factors in psoriasis patients.

Objectives

To determine whether there is a change in the results of the tuberculin skin test (TST) or the interferon-gamma release assay (IGRA) in psoriasis patients living in tuberculosis (TB)-endemic area after 12 weeks of methotrexate (MTX) treatment and to investigate the association of the test results with clinical and inflammatory markers.

Methods

Forty-five patients were selected for a prospective single-arm self-controlled study and followed for at least 18 months. The TST, IGRA, Psoriasis Area and Severity Index (PASI), and inflammatory factors (erythrocyte sedimentation rate (ESR), C-reactive protein, interferon-gamma (IFN-γ), and tumor necrosis factor-alpha levels), were determined before and after 12 weeks of oral 15 mg per week MTX administration and compared. The associations between the IGRA and TST results were verified before and after treatment according to inflammatory factors and clinical characteristics (age, blood glucose, weight, body mass index, disease duration, and PASI).

Results

We collected data on 25 patients who completed the full course of therapy and the follow-up. None of the patients developed TB. TST positivity was significantly elevated at week 12 (25% baseline vs 44% at week 12, P < 0.037). Three IGRAs followed the TST conversions. There was no difference between TST and IGRA pre- or posttreatment. Serum IFN-γ increased significantly in week 12 (15.95 pg/ml baseline vs 18.82 pg/ml at week 12, P < 0.005) and tended to be higher among TST-positive patients (P = 0.072). The baseline IGRA was associated with a higher ESR (P = 0.038). None of the test results were associated with clinical characteristics.

Conclusions

In addition to the classic booster effect, TST conversions in patients using MTX can occur due to an increase in IFN-γ. However, it is not possible to exclude true TST conversions. Therefore, other diagnostic methods, like IGRA or chest tomography, should be used when the TST has intermediate results.

Trends in diagnostic methods and treatment of latent tuberculosis infection in a tertiary care center from 2000 to 2017

Screening for latent tuberculosis infection (LTBI) is indicated before immunosuppressive therapies but is complicated by lack of a gold standard and limited by, e.g., immunosuppression. This study aimed to investigate a series of patients diagnosed with LTBI during screening before immunosuppressive therapy, describing how the use of diagnostic tests and treatment evolved over time. This retrospective cohort study included all individuals diagnosed with LTBI during screening before intended immunosuppressive therapy in a tertiary care hospital between January 2000 and December 2017. Evidence for LTBI, including history, tuberculin skin test (TST), QuantiFERON (QFT) result and suggestive lesions on chest radiography (CXR), and CT scan if available, was analyzed. The study included 295 individuals with LTBI, with median follow-up of 3.8 years (IQR 1.7–7.4 years). During screening, TST, QFT, and CXR were positive in 80.8%, 53.4%, and 22.7%, respectively. Chest CT revealed lesions associated with past tuberculosis infection in around 70%, significantly more frequent than CXR. In patients diagnosed with LTBI, we observed that the use of TST declined over time whereas the use of QFT increased, and that isoniazid was replaced with rifampicin as preferential treatment. Preventive treatment was started in 82.3%, of whom 88.6% completed treatment. During follow-up, no individuals developed active tuberculosis. The diagnosis of LTBI was based on history, TST, QFT, and/or CXR in nearly every possible combination, but mostly on TST and QFT. The most striking trends were the decreased use of TST, increased use of QFT, and the replacement of isoniazid with rifampicin for treatment.

Indian guidelines on imaging of the small intestine in Crohn's disease: A joint Indian Society of Gastroenterology and Indian Radiology and Imaging Association consensus statement

The Indian Society of Gastroenterology (ISG) Task Force on Inflammatory Bowel Disease and the Indian Radiological and Imaging Association (IRIA) developed combined ISG-IRIA evidence-based best-practice guidelines for imaging of the small intestine in patients suspected to have or having Crohn's disease. The 29 consensus statements, developed through a modified Delphi process, are intended to serve as reference for teaching, clinical practice, and research.

Radiological Signs of Latent Tuberculosis on Chest Radiography: A Systematic Review and Meta-Analysis

Objective

Current guidelines recommend screening for latent tuberculosis infection (LTBI) with a tuberculin skin test (TST) or interferon gamma release assay (IGRA), or both. Many also recommend chest radiography (CXR), although its added value is uncertain. This systematic review assessed the prevalence of abnormalities suggestive of LTBI on CXR (LTBI-CXR lesions) and evaluated the strength of the association.

Method

We searched 4 databases up to September 2017 and systematically reviewed cross-sectional and cohort studies reporting LTBI-CXR lesions in individuals with a positive TST or IGRA, or both, result. Prevalence estimates were pooled using random effects models and odds ratios (ORs) were used to calculate risk estimates.

Results

In the 26 included studies, the pooled proportion of individuals with LTBI having LTBI-CXR lesions was 0.15 (95% confidence interval [CI], 0.12–0.18]. In 16 studies that reported on individuals with LTBI and uninfected controls, LTBI-CXR lesions were associated with a positive TST result ≥ 5 mm or ≥ 10 mm (OR, 2.45; 95% CI, 1.00–5.99; and OR, 2.06; 95% CI, 1.38–3.09, respectively) and with a positive QuantiFERON result (OR, 1.99; 95% CI, 1.17–3.39) compared to CXR in uninfected controls. Although few studies reported specified lesions, calcified nodules were most frequently reported in individuals with LTBI (proportion, 0.07; 95% CI, 0.02–0.11).

Conclusions

Lesions on CXR suggestive of previous infection with Mycobacterium tuberculosis were significantly associated with positive tests for LTBI, although the sensitivity was only 15%. This finding may have added value when detection of past LTBI is important but immunodiagnostic tests may be unreliable.

Limited benefit of CT scans in tuberculosis contact tracing

OBJECTIVE

The detection of abnormal findings on computed tomography (CT) scans of tuberculosis contacts combined with normal plain radiographs contributes to the early detection of tuberculosis. However, the benefit of the early detection of abnormalities for the prevention of active tuberculosis during follow-up requires evaluation.

METHOD

We conducted retrospective comparison of the existence of CT scans of tuberculosis contacts without findings of active tuberculosis on plain radiographs at a hospital in Japan.

RESULTS

Among 243 contacts without CT scans, five developed tuberculosis during follow-up. Among 229 contacts with CT scans, 24 were judged as targets of multi-drug therapy since their CT findings were suggestive of active tuberculosis at the time of the CT screening. Among 205 contacts judged as having latent tuberculous infection with CT screening, three developed tuberculosis diseases during follow-up.

CONCLUSION

CT scans detected abnormal findings among contacts without abnormalities of plain radiographs but there were some contacts that developed tuberculosis diseases among those with contact investigation including CT scan. The value of CT is equivocal considering the balance of true treatment, overtreatment and harm of radiation.

The Application of T.SPOT-TB Assay for Early Diagnosis of Active Tuberculosis in Chronic Kidney Disease Patients Receiving Immunosuppressive Treatment

Background: The current study investigated the clinical application of the T-SPOT.TB assay for detecting tuberculosis (TB) infection in chronic kidney disease patients treated with immunosuppressive therapy. Methods: Clinical data from 91 patients were retrospectively analyzed. The rate of positive T-SPOT.TB results and spot numbers were compared before and after treatment. Clinical characteristics that may affect the test results were also investigated. Results: Two active TB cases were observed after immunosuppressive treatment, and eight patients with negative T-SPOT.TB results at baseline had positive results after treatment. No significant changes in spot numbers were observed for patients who were positive at baseline. Compared with pretreatment baseline, patients who received medium/high doses of corticosteroids had a greater number of T-SPOT.TB positive results (p = 0.016) and CFP-10 spots (p = 0.041) after treatment. For patients who received combination therapy with medium/high doses of corticosteroids, the T-SPOT.TB positive rate (p = 0.046) and CFP-10 spot number (p = 0.041) were increased after treatment, with no significant changes in the total number of spots or ESAT-6 spots. For those who received combination therapy with low doses of corticosteroids and those who received single immunosuppressive medication, there were no significant differences in the T-SPOT.TB positive rate, total spot number, or numbers of ESAT-6 and CFP-10 spots. Conclusion: The increase in positive T-SPOT.TB results was mainly associated with medium/high doses of glucocorticoids. The active TB cases might represent new infections. Regular monitoring using the T-SPOT.TB assay will help in the early detection of active TB.

Abnormalities suggestive of latent tuberculosis infection on chest radiography; how specific are they?

Background

Several radiological features have been reported in association with latent tuberculosis infection (LTBI) but it has not been studied which are specific. The aim of this study was to evaluate allegedly characteristic abnormalities on chest radiography (CXR) in patients with LTBI compared to uninfected controls.

Methods

From 236 patients tested with QuantiFERON-TB Gold In-Tube (QFT), the CXR was re-evaluated in a blinded fashion for fibrotic scarring, (non-)calcified nodules and pleural thickening. LTBI was defined as presence of a positive QFT result and/or positive tuberculin skin test result stratified by Bacille Calmette-Guérin-vaccination status.

Results

Any predefined abnormality of LTBI was observed in 116/236 (49.2%) patients, the frequency not being different between groups. However, the specificity for LTBI of a fibrotic scar ≥ 2 cm² was 100% [95% CI: 92.0%–100%] and of a calcified nodule ≥1.5 mm was 95.7% [95% CI: 85.2%–99.5%]. The frequency of non-calcified nodules and pleural thickening did not differ between groups.

Conclusion

Only a fibrotic scar ≥ 2 cm² and/or a calcified nodule ≥1.5 mm were significantly associated with LTBI. This finding is clinically relevant mainly in patients who are at significant risk of TB reactivation and in whom indirect diagnostic tests may be unreliable.

Imaging of the small intestine in Crohn's disease: Joint position statement of the Indian Society of Gastroenterology and Indian Radiological and Imaging Association

The Indian Society of Gastroenterology (ISG) Task Force on Inflammatory Bowel Disease and the Indian Radiological and Imaging Association (IRIA) developed combined ISG-IRIA evidence-based best-practice guidelines for imaging of the small intestine in patients with suspected or known Crohn's disease. These 29 position statements, developed through a modified Delphi process, are intended to serve as reference for teaching, clinical practice, and research.