Interferon-gamma release assays are a better tuberculosis screening test for hemodialysis patients: A study and review of the literature

Diagnosis of Latent Tuberculosis Infection in Hemodialysis Patients: TST versus T-SPOT.TB

Hemodialysis (HD) patients should be screened for latent tuberculosis (TB) infection. We aimed to determine the frequency of latent TB infection in HD patients and to compare the effectiveness of the tests used. The files of 56 HD patients followed between 1 January 2021 and 1 October 2022 were retrospectively analyzed. Demographic data, the presence of the Bacillus Calmette-Guerin (BCG) vaccine, whether or not the patients had previously received treatment for TB before, the status of encountering a patient with active TB of patients over 18 years of age, without active tuberculosis and who had a T-SPOT.TB test or a Tuberculin Skin Test (TST) were obtained from the patient files. The presence of previous TB in a posterior-anterior (PA) chest X-ray was obtained by evaluating PA chest X-rays taken routinely. Of the patients, 60.7% (n = 34) were male and their mean age was 60.18 ± 14.85 years. The mean duration of dialysis was 6.43 ± 6.03 years, and 76.8% (n = 43) had 2 BCG scars. The T-SPOT.TB test was positive in 32.1% (n = 18). Only 20 patients (35.7%) had a TST and all had negative results. While the mean age of those with positive T-SPOT.TB results was higher (p = 0.003), the time taken to enter HD was shorter (p = 0.029). T-SPOT.TB test positivity was higher in the group that had encountered active TB patients (p = 0.033). However, no significant difference was found between T-SPOT.TB results according to BCG vaccine, albumin, urea and lymphocyte levels. Although T-SPOT.TB test positivity was higher in patients with a previous TB finding in a PA chest X-ray, there was no statistically significant difference (p = 0.093). The applicability of the TST in the diagnosis of latent TB infection in HD patients is difficult and it is likely to give false-negative results. The T-SPOT.TB test is not affected by the BCG vaccine and immunosuppression. Therefore, using the T-SPOT.TB test would be a more appropriate and practical approach in the diagnosis of latent TB in HD patients.

The prevalence of latent tuberculosis infection in patients with chronic kidney disease: A systematic review and meta-analysis

Objective

To estimate the prevalence of latent tuberculosis infection (LTBI) in chronic kidney disease (CKD) patients.

Methods

This study was conducted following the PRISMA guidelines. We identified, 3694 studies from the whole search, and 59 studies were included. Each study's quality was assessed using JBI checklist. We employed STATA version 17 for statistical analysis. We assessed heterogeneity using I2 heterogeneity test. Publication bias was assessed using funnel plot and Egger's test. We estimated the pooled LTBI prevalence in CKD patients along with 95%CI.

Results

The pooled prevalence of LTBI among CKD patients using data collected from 53 studies having 12,772 patients was 30.2% (95%CI; 25.5, 34.8). The pooled prevalence among pre-dialysis, hemodialysis, peritoneal dialysis, and renal transplanted patients was 17.8% (95%CI; 3.3, 32.4), 34.8% (95%CI; 29.1, 40.5), 25% (95%CI; 11, 38), and 16% (95%CI; 7, 25), respectively. The pooled prevalence of LTBI stratified by the laboratory screening methods was 25.3% (95%CI: 20.3-30.3) using TST, 28.0% (95%CI; 23.9-32.0) using QFT, and 32.6%, (95%CI: 23.7-41.5) using T-SPOT.

Conclusion

There is high prevalence of LTBI among CKD patients mainly in patients on dialysis. Thus, early diagnosis and treatment of LTBI in CKD patients should be performed to prevent active TB in CKD patients.PROSPERO registration number: CRD42022372441.

Risk factors of latent tuberculosis among chronic kidney disease with routine haemodialysis patients

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Since tuberculosis still become an important health problem in the world, especially in developing countries, CKD patients also become a high-risk population to TBC infection.

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Due to immunity impairment in CKD patients, particularly who are routinely hemodialyzed, tuberculosis is not always clinically manifested (latent).

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However, tuberculosis among CKD patients contribute to greater morbidity, quality of life and morbidity. Hence, we investigated the factors that associated with latent tuberculosis among CKD on haemodialysis patients.

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By understanding it, management of CKD patients could be more comprehensive, and the morbidity and mortality could be decreased while quality of life could be increased.

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We also provide the first documentation study of tuberculosis among CKD on haemodialysis patients in Indonesia, one of the tuberculosis endemic country.

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According our study, smoking status and HD adequacy based on URR < 73% are associated factors that contribute to LTB among CKD on HD patients.

Introduction

Methods

Results

Conclusion

Agreement between the results of tuberculin skin test and Interferon-Gamma Release Assays in renal transplant candidates

Introduction:

Identification of latent tuberculosis (TB) infection is important in kidney transplant candidates. Due to the absence of a gold standard, both tuberculin skin test (TST) and interferon-gamma release assays (IGRA) are used to screen patients. The aim of this study was to evaluate the agreement of these two tests in patients undergoing renal transplantation.

Materials and Methods:

Two hundred kidney transplant candidates at a referral center in 2014–2017 were included in this study. TST and Quantiferon-Gold (QFT-G) tests were performed for all patients before transplantation. In case of a positive result in any of the tests, patients were administered a 9-month prophylaxis treatment using isoniazid. Cohen's kappa coefficient (k) test was used to determine the agreement between the two tests.

Results:

The mean age of patients was 40.72 ± 18.33. Nine (4.5%) patients had positive TST and 16 (8%) had positive IGRA. Concordance of the two tests was evaluated as medium (κ = 0.44 and P < 0.001). No association was found between the underlying causes of renal failure and skin test positive or IGRA. The tests showed a poor agreement among diabetics, candidates of re-transplantation, and those who were on dialysis for longer than a year (κ < 0.20).

Conclusion:

TST or IGRA can be used to screen TB in kidney transplant candidates with a moderate agreement. However, we suggest using both TST and QFT-G in diabetics, re-transplant candidates, and those on dialysis for >1 year.

Discordance in latent tuberculosis (TB) test results in patients with end-stage renal disease

OBJECTIVES

This natural experiment was designed to assess the impact of exposure to an active case of tuberculosis (TB) on a group of immunosuppressed individuals, with end-stage renal disease over an extended follow-up.

STUDY DESIGN

Close contacts of people with sputum smear-positive Mycobacterium tuberculosis are at high risk of infection, particularly immunosuppressed individuals. An infectious TB healthcare worker worked in a renal dialysis unit for a month before diagnosis, with 104 renal dialysis patients, was exposed for ≥8 h.

METHODS

Patients were informed and invited for screening 8-10 weeks postexposure. They either underwent standard two-step assessment with tuberculin skin test (TST) and QuantiFERON^®-TB Gold (Cellestis GmbH; QFN) interferon-gamma release assay (IGRA) or after consent, enrolled in a study where these two tests were performed simultaneously with T-SPOT^®-TB (Oxford Immunotec Ltd; TSPOT). Patients within the study were followed up for 2 years from exposure, with QFN and TSPOT repeated at months 3 and 6 from the first testing.

RESULTS

Of 104 exposed individuals, 75 enrolled in the study. There was a high degree of discordance among QFN, TSPOT and TST. This was seen at both the first time point and also over time in subjects who were retested. No patients had active TB at the baseline testing. None received treatment for latent TB infection. Over the following 2 years, no one developed TB disease.

CONCLUSION

This study suggests that there is a low risk of progression to active TB in low-incidence countries even in high-risk groups. This plus the degree of the test result discordance emphasises the complexities of managing TB in such settings as it is unclear which of these tests, if any, provides the best diagnostic accuracy.

Interferon-gamma response to the treatment of active pulmonary and extra-pulmonary tuberculosis

BACKGROUND

Interferon-gamma (IFN-γ) release assays (IGRAs) are used to diagnose tuberculosis (TB) but not to measure treatment response.

OBJECTIVE

To measure IFN-γ response to active anti-tuberculosis treatment.

DESIGN

Patients from the Henan Provincial Chest Hospital, Henan, China, with TB symptoms and/or signs were enrolled into this prospective, observational cohort study and followed for 6 months of treatment, with blood and sputum samples collected at 0, 2, 4, 6, 8, 16 and 24 weeks. The QuantiFERON® TB-Gold assay was run on collected blood samples. Participants received a follow-up telephone call at 24 months to determine relapse status.

RESULTS

Of the 152 TB patients enrolled, 135 were eligible for this analysis: 118 pulmonary (PTB) and 17 extra-pulmonary TB (EPTB) patients. IFN-γ levels declined significantly over time among all patients (P = 0.002), with this decline driven by PTB patients (P = 0.001), largely during the initial 8 weeks of treatment (P = 0.019). IFN-γ levels did not change among EPTB patients over time or against baseline culture or drug resistance status.

CONCLUSION

After 6 months of effective anti-tuberculosis treatment, IFN-γ levels decreased significantly in PTB patients, largely over the initial 8 weeks of treatment. IFN-γ concentrations may offer some value for monitoring anti-tuberculosis treatment response among PTB patients.

Predictive value of the tuberculin skin test and QuantiFERON-tuberculosis Gold In-Tube test for development of active tuberculosis in hemodialysis patients

BACKGROUND

Hemodialysis (HD) patients are at increased risk of reactivation of latent tuberculosis infection (LTBI) compared with the general population. QuantiFERON-TB Gold (QFT-G) for LTBI detection is more promising than tuberculin skin test (TST) in HD patients.

AIM

In our study, we evaluated the value of the TST and QFT-G In-Tube (QFG-IT) test in the development of active tuberculosis (TB), in the HD patients, and in healthy controls.

METHODS

The study enrolled 95 HD patients and ninety age-matched, healthy controls. The TST and QFG-IT were performed. All the subjects were followed up 5 years for active TB disease.

RESULTS

Compared to the healthy controls, a high prevalence of LTBI was found in the HD patients by QFG-IT (41% vs. 25%). However, no significant difference was detected by TST (32% vs. 31%). Four HD patients and one healthy control progressed to active TB disease within the 5-year follow-up. For active TB discovered subjects, QFG-IT was positive in all, but TST was positive in two (one patient and one healthy control). In HD patients; sensitivity, specificity, positive and negative predictive values of QFG-IT, and TST for active TB was 100% and 25%, 62% and 67%, 10%, and 3%, and 100% and 95%, respectively. Receiver operating curve analysis revealed that the results are significantly different (P = 0.04).

CONCLUSION

QFG-IT test is a more useful diagnostic method than TST for detecting those who will progress to active TB in HD patients.

Demographics and prevalence of positive QuantiFERON-TB Gold In-Tube test in renal transplant candidates

BACKGROUND

Latent tuberculosis infection (LTBI) screening prior to solid organ transplantation is standard of care. QuantiFERON-TB Gold In-Tube (QFT-GIT) test is the preferred diagnostic test for renal transplant candidates (RTC). QFT-GIT reversions and the potential delay of living-donor kidney transplantation (LDKT) because of QFT-GIT positivity have not been examined previously in RTC.

METHODS

We evaluated the prevalence of positive QFT-GIT in RTC from January 1 through December 31, 2011. In addition, we examined the demographic and renal disease data differences between QFT-GIT-positive and -negative patients, changes in QFT-GIT results, and positive QFT-GIT results reverting to negative. Lastly, we evaluated if QFT-GIT-positive patients were less likely to undergo LDKT within 6 months of QFT-GIT testing.

RESULTS

In total, 722 RTC were analyzed, 16% of whom had positive QFT-GIT. The QFT-GIT-positive patients were more likely to be older and foreign-born, P < 0.0001. Haitians had the highest prevalence. Of the 119 QFT-GIT-positive patients, 25% had low/intermediate-positive results and were more likely to revert to negative, compared with patients with high-positive QFT-GIT results (50% vs. 0%, P = 0.01). A trend was seen toward fewer QFT-GIT-positive patients undergoing LDKT, compared with QFT-GIT-negative patients (0% vs. 3%, P = 0.09).

CONCLUSIONS

Our high prevalence was likely a result of the high number of foreign-born RTC. Half of our small subset of low/intermediate-positive QFT-GIT patients reverted to negative. QFT-GIT-positive patients were more likely to have their LDKT delayed.

Detecting latent tuberculosis in compromised patients

PURPOSE OF REVIEW

The detection of latent tuberculosis infection (LTBI) in different categories of compromised patients is reviewed with focus on the role of strategies incorporating immunodiagnostic tests and analysis of epidemiological and clinical risk factors.

RECENT FINDINGS

The development of active tuberculosis (TB) is increased in compromised patients and is closely related to determinants for disease reactivation or newly acquired TB infection. A targeted detection of LTBI in these high-risk groups should be performed especially if preventive treatment is planned. The performance of immunodiagnostic tests is highly variable among different groups of immunocompromised individuals. Findings of cross-sectional studies indicate a better diagnostic accuracy of interferon-γ release assays over the tuberculin skin test. The critical issue is that in low-incidence countries, the positive and negative predictive values of any of immunodiagnostic tests were very poor. A targeted testing process involving analysis of TB risk factors increases the predictive positive values of immunodiagnostic tests and may improve LTBI detection.

SUMMARY

The LTBI detection in immunocompromised patients is a challenge. The development of new immunological biomarkers and integrated clinical and epidemiological strategies are needed to identify LTBI in compromised individuals and to plan preventive chemotherapies in those at risk of developing active TB.