High rates of indeterminate interferon‐gamma release assays for the diagnosis of latent tuberculosis infection in liver transplantation candidates

Characteristics, management, and outcome of tuberculosis after liver transplant: A case series and literature review

BACKGROUND

Liver transplant recipients are at risk of tuberculosis, which is particularly difficult-to diagnose and to treat in this population.

METHODS

Retrospective study of all cases of tuberculosis diagnosed from 2007 to 2022 in the French network of liver transplant sites.

RESULTS

Twenty-three liver transplant recipients were diagnosed with tuberculosis (six females, median age 59 years [interquartile range, 54-62]), with a median time lapse of 10 months [5-40.5] after transplant, and 38 days [26-60] after symptoms onset. Primary modes of pathogenesis were latent tuberculosis reactivation (n = 15) and transplant-related transmission (n = 3). Even though most patients with pre-transplant data had risk factors for tuberculosis (11/20), IFN-gamma release assay was performed in only three. Most cases involved extra-pulmonary tuberculosis (20/23, 87 %). With median follow-up of 63 months [24-108], five patients died (22 %), including four tuberculosis-related deaths.

CONCLUSIONS

Extrapulmonary tuberculosis is a severe disease in liver transplant recipients. Systematic pre-transplant screening of latent tuberculosis may prevent most of them.

A Retrospective Study of Factors Contributing to the Performance of an Interferon-Gamma Release Assay Blood Test for Tuberculosis Infection

BACKGROUND

Tuberculosis (TB) remains a significant global health concern. Accurate detection of latent TB infection is crucial for effective control and prevention. We aimed to assess the performance of an interferon-gamma release assay blood test (QuantiFERON-TB Gold Plus [QFT-Plus]) in various clinical contexts and identify conditions that affect its results.

METHODS

We conducted a retrospective analysis of 31 000 QFT-Plus samples collected from 26 000 subjects at a tertiary hospital in South Korea over a 4-year period and compared the rates of positivity and indeterminate results across diverse clinical situations. We also analysed the contribution of the QuantiFERON TB2 tube to the test's sensitivity and determined optimal cutoff values for 3 hematologic parameters to distinguish false-negative results. These cutoff values were validated in a separate cohort of subjects with microbiologically confirmed subclinical TB.

RESULTS

Rates of QFT-Plus positivity and indeterminate results were disparate across diagnoses. The TB2 tube increased QFT-Plus sensitivity by 4.1% (95% CI, 1.1%-7.0%) in patients with subclinical TB. Absolute lymphocyte count ≤1.19 × 109/L, absolute neutrophil count ≥5.88 × 109/L, and neutrophil-to-lymphocyte ratio ≥4.33 were effective criteria to discriminate false-negative QFT-Plus results. Application of the hematologic criteria, individually or combined with mitogen response <10 IU/mL, substantially improved performance in the main study cohort and the validation cohort.

CONCLUSIONS

These findings highlight the influence of clinical context and patient hematologic profiles on QFT-Plus results. To minimise neglected latent TB infections due to false-negative QFT-Plus results, serial retesting is advisable in patients with severe lymphopenia or neutrophilia, particularly when the mitogen response is <10 IU/mL.

Risk of progression to active tuberculosis for indeterminate interferon-gamma release assay in immunocompromised individuals: a systematic review and meta-analysis

BACKGROUND

Limited data exist on assessing the risk of active tuberculosis (TB) in immunocompromised individuals during screening for latent tuberculosis infection (LTBI).

OBJECTIVES

To assess the risk of progression to active TB for indeterminate interferon-γ release assays (IGRA) results in immunocompromised individuals during screening for LTBI.

DATA SOURCES

PubMed, Embase, Web of Science, and the Cochrane Library were searched without start date or language restrictions on 18 April 2023.

STUDY ELIGIBILITY CRITERIA

Cohort study or randomized controlled trials that investigated the risk of progression to active TB for indeterminate IGRA during LTBI screening.

PARTICIPANTS

Immunocompromised individuals. TEST: IGRA (T-SPOT.TB and QuantiFERON).

REFERENCE STANDARD

None.

ASSESSMENT OF RISK OF BIAS

A modified version of the Newcastle-Ottawa Scale.

METHODS OF DATA SYNTHESIS

Fixed effects meta-analysis was used to obtain two pooled risk ratios (RRs). RR-ip represented disease progression rate in untreated individuals with indeterminate IGRA versus positive IGRA. RR-in represented disease progression rate in untreated individuals with indeterminate IGRA versus negative IGRA.

RESULTS

Among the 5102 identified studies, 28 (14 792 immunocompromised individuals) were included. The pooled RR-ip and RR-in for cumulative incidence were 0.51 (95% CI, 0.32-0.82; I2 = 0%) and 2.94 (95% CI, 1.78-4.85; I2 = 0%), respectively. In addition, 11 studies reporting person-year data were included to verify the reliability of cumulative incidence results. The pooled RR-ip and RR-in for person-year incidence were 0.40 (95% CI, 0.19-0.82; I2 = 13%) and 2.67 (95% CI, 1.24-5.79; I2 = 23%), respectively.

DISCUSSION

Indeterminate IGRA results in immunocompromised individuals may represent an intermediate risk of progression to active TB, with half the risk for positive results and three times for negative results. Proper follow-up and management of patients with indeterminate results are crucial for mitigating progression risk and improving patient outcomes.

Screening for Latent Tuberculosis Infection in Solid Organ Transplant Recipients to Predict Active Disease: A Systematic Review and Meta-Analysis of Diagnostic Studies

BACKGROUND

This is a systematic review and meta-analysis of diagnostic test accuracy studies to assess the predictive value of both tuberculin skin test (TST) and interferon-gamma release assays (IGRA) for active tuberculosis (TB) among solid organ transplantation (SOT) recipients.

METHODS

Medline, Embase, and the CENTRAL databases were searched from 1946 until June 30, 2022. Two independent assessors extracted data from studies. Sensitivity analyses were performed to investigate the effect of studies with high or low risk of bias. Methodological quality of each publication was assessed using QUADAS-2.

RESULTS

A total of 43 studies (36 403 patients) with patients who were screened for latent TB infection (LTBI) and who underwent SOT were included: 18 were comparative and 25 noncomparative (19 TST, 6 QuantiFERON-TB Gold In-Tube [QFT-GIT]). For IGRA tests taken together, positive predictive value (PPV) and negative predictive value (NPV) were 1.2% and 99.6%, respectively. For TST, PPV was 2.13% and NPV was 95.5%. Overall, PPV is higher when TB burden is higher, regardless of test type, although still low in absolute terms. Incidence of active TB was similar between studies using LTBI prophylaxis (mean incidence 1.22%; 95% confidence interval [CI], .2179-2.221) and those not using prophylaxis (mean incidence 1.045%; 95% CI, 0.2731-1.817; P = .7717). Strengths of this study include the large number of studies available from multiple different countries; limitations include absence of gold standard for diagnosis of latent TB and low incidence of active TB.

CONCLUSIONS

We found both TST and IGRA had a low PPV and high NPV for the development of active TB posttransplant. Further studies are needed to better understand how to prevent active TB in the SOT population.

Indeterminate results of interferon gamma release assays in the screening of latent tuberculosis infection: a systematic review and meta-analysis

Objectives

We aimed to evaluate the indeterminate rate of interferon gamma release assays (IGRAs) in the detection of latent tuberculosis infection (LTBI).

Methods

On 15 November 2022, we searched the PubMed® (National Library of Medicine, Bethesda, MD, USA), Embase® (Elsevier, Amsterdam, the Netherlands), and Cochrane Library databases in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Two investigators independently extracted the study data and assessed their quality using a modified quality assessment of diagnostic accuracy studies (i.e., QUADAS-2) tool. A random-effects model was used to calculate pooled results.

Results

We included 403 studies involving 486,886 individuals and found that the pooled indeterminate rate was 3.9% (95% CI 3.5%-4.2%). The pooled indeterminate rate for QuantiFERON®-TB (QFT) was similar to that for T-SPOT®.TB (T-SPOT) [odds ratio (OR) = 0.88, 95% CI 0.59-1.32]; however, the indeterminate rate for a new generation of QFT (QFT-plus) was lower than that of T-SPOT (OR = 0.24, 95% CI 0.16-0.35). The indeterminate rate in the immunocompromised population was significantly higher than that in healthy controls (OR = 3.51, 95% CI 2.11-5.82), and it increased with the reduction of CD4+ cell count in HIV-positive patients. Children's pooled indeterminate rates (OR = 2.56, 95% CI 1.79-3.57) were significantly higher than those of adults, and the rates increased as the children's age decreased.

Conclusion

On average, 1 in 26 tests yields indeterminate IGRA results in LTBI screening. The use of advanced versions of the QuantiFERON-TB assay (QFT-plus), may potentially reduce the occurrence of an indeterminate result. Our study emphasizes the high risk of immunosuppression and young age in relation to indeterminate IGRA, which should receive more attention in the management of LTBI.

Systematic review registration

PROSPERO https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020211363, CRD42020211363.

The cascade of care in testing and treatment of latent tuberculosis infection in liver transplant candidates

BACKGROUND

Testing and treatment for latent tuberculosis infection (LTBI) can mitigate risk of active tuberculosis (TB) post-liver transplant (LT). Testing and treatment completion rates have been reported low in this population. Our study aims to quantify the proportion of LT candidates who completed LTBI care cascade in our center.

METHODS

A retrospective chart review was conducted on LT candidates from 2012 to 2021. Primary outcome was the proportion of patients who completed each cascade stage. Secondary outcome was an analysis of factors associated with positive and indeterminate LTBI testing.

RESULTS

Of the 273 LT candidates, 265 (97.1%) were referred to transplant infectious disease (TID), 264 (96.7%) had orders for interferon-gamma release assay (IGRA), 262 (96%) underwent TID evaluation, and 259 (94.9%) completed IGRA. Twenty had LTBI, and 18 were treatment naïve and recommended for treatment. Of the 18, 15 (83.3%) agreed to therapy, 14 (77.8%) initiated treatment, and 12 (66.7%) completed treatment. No posttransplant TB reactivation occurred. Patients born in Asia, previous incarceration, past military service, and granuloma findings on chest imaging were likely to have positive IGRA (p < .05). Older age and travel to TB-endemic countries were likely to have indeterminate IGRA (p < .05). Indeterminate IGRAs were more common in QuantiFERON (QTF)-Gold Plus TB (15.3%) versus QTF-Gold TB (9.3%, p < .001).

CONCLUSIONS

High rates of LTBI testing and treatment initiation and completion can be attributed to a standardized process that includes TID evaluation. Future studies in larger cohort are needed to better understand factors that can optimize the completion rates of LTBI treatment in LT candidates.

Diagnostic Value of Interferon-Gamma Release Assays for Tuberculosis in the Immunocompromised Population

Interferon-gamma release assays (IGRAs) are widely used in the diagnosis of Mycobacterium tuberculosis (M. tuberculosis) infection by detecting interferon-γ released by previously sensitized T-cells in-vitro. Currently, there are two assays based on either enzyme-linked immunosorbent assay (ELISA) or enzyme-linked immunospot (ELISPOT) technology, with several generations of products available. The diagnostic value of IGRAs in the immunocompromised population is significantly different from that in the immunocompetent population because their results are strongly affected by the host immune function. Both physiological and pathological factors can lead to an immunocompromised situation. We summarized the diagnostic value and clinical recommendations of IGRAs for different immunocompromised populations, including peoplewith physiological factors (pregnant and puerperal women, children, and older people), as well as people with pathological factors (solid organ transplantation recipients, combination with human immunodeficiency virus infection, diabetes mellitus, end-stage renal disease, end-stage liver disease, and chronic immune-mediated inflammatory diseases). Though the performance of IGRAs is not perfect and often requires a combination with other diagnostic strategies, it still has some value in the immunocompromised population. Hopefully, the newly developed IGRAs could better target this population.

Mycobacterium tuberculosis in solid organ transplant donors and recipients

PURPOSE OF REVIEW

Due to impaired immune response, solid organ transplant (SOT) recipients are susceptible to tuberculosis (TB) and its subsequent morbidity and mortality. Current prevention strategies, diagnostic and treatment approach to TB infection in donors and recipients were reviewed in this article.

RECENT FINDINGS

Screening of latent tuberculosis infection (LTBI) in donors and recipients is the cornerstone of TB-preventive strategy in recipients and requires an assessment of TB risk factors, TB-specific immunity testing, and radiographic evaluation. Interferon-gamma release assay has superseded the tuberculin skin test in LTBI evaluation despite its recognized limitations. LTBI treatment should be offered to transplant candidates and living donors before transplantation and donation, respectively. Diagnosis of TB disease can be challenging because of nonspecific clinical presentation in the recipient and is limited by the sensitivity of current diagnostics. The approach to LTBI and TB disease treatment is similar to the general population, but can be challenging because of potential drug interactions and toxicities.

SUMMARY

The appropriate evaluation of donors and recipients for TB can mitigate posttransplant TB disease. Current approaches to diagnosis and treatment parallels that of immunocompetent hosts. Future research evaluating existing and novel diagnostics and treatment in transplant recipients is needed.

Use of T Cell Mediated Immune Functional Assays for Adjustment of Immunosuppressive or Anti-infective Agents in Solid Organ Transplant Recipients: A Systematic Review

Background: Defining the optimal dosage of the immunosuppressive or duration of anti-infective agents is a challenge in solid organ transplant (SOT) recipients. We aimed to systematically review the literature regarding the use of T cell mediated immune functional assays (IFAs) for adjustment of the immunosuppressive or anti-infective agents in SOT recipients. Methods: We systematically searched PubMed, Scopus, EMBASE, Web of Science (WOS), Cochrane Central Register of Controlled Trials (CENTRAL), and ClinicalTrials.gov to find human interventional studies or study protocols that used either in-house or commercially available IFAs for adjustment of the immunosuppressive or anti-infective agents in SOT recipients. Results: We included six clinical trials and six study protocols. Four out of the six clinical trials used interferon-γ release assays for cytomegalovirus (IGRA-CMV), and five out of the six registered study protocols planned to use IGRA-CMV for adjustment of anti-CMV antiviral (Valganciclovir) prophylaxis or preemptive therapy in SOT recipients. Primary or secondary anti-CMV prophylaxes were discontinued in SOT recipients who had positive IGRA-CMV results without an increase in the rate of CMV infection or reactivation. Among other IFAs, one clinical trial used interferon-γ release assays for tuberculosis (IGRA-TB), and one study used ImmuKnow for adjustment of the duration and dosage of isoniazid and tacrolimus, respectively. Conclusion: Our systematic review supports a promising role for the IGRA-CMVs for adjustment of the duration of anti-CMV antiviral prophylaxis in SOT recipients. There are limited data to support the use of IFAs other than IGRA-CMVs for adjustment of immunosuppressive or anti-infective agents. Further multicenter randomized clinical trials using IFAs other than IGRA-CMVs may help in personalized immunosuppressive or prophylactic anti-infective therapy in SOT recipients.

Comparison of tuberculin skin test and interferon gamma release assay in pediatric candidates of heart transplantation and a 2-year follow-up

BACKGROUND

Currently, tuberculin skin test (TST) and interferon gamma release assay (IGRA) are used to find the latent tuberculosis infection (LTBI) cases in the candidates of heart transplantation. Therefore, this study aimed to compare TST and IGRA to diagnose LTBI in pediatric heart transplant candidates.

METHODS

This cross-sectional study was performed on 50 children, who were candidates for heart transplantation, of whom 42 cases underwent heart transplantation in Shahid Rajaie Cardiovascular, Medical, and Research center, Tehran, Iran, from 2016 to 2017.

RESULTS

Participants of the study included 24 male patients (%48) (p-value = 0.67). The mean age of the patients was 8.18 ± 4.27 years (1-16 years). According to the results, IGRA was negative in all patients, and no indeterminate result was reported, while the purified derivative test (PPD) was positive in three (6%) cases. In comparison with QFT, an accuracy of 94% was achieved for TST to diagnose Mycobacterium tuberculosis infection.

CONCLUSIONS

It seems that TST can still be used as an accurate test for screening LTBI in pediatric candidates for heart transplantation.

Is latent tuberculosis infection challenging in Iranian health care workers? A systematic review and meta-analysis

Background

The high chances of getting latent tuberculosis infection (LTBI) among health care workers (HCWs) will an enormous problem in low and upper-middle-income countries.

Method

Search strategies were done through both national and international databases include SID, Barakat knowledge network system, Irandoc, Magiran, Iranian national library, web of science, Scopus, PubMed/MEDLINE, OVID, EMBASE, the Cochrane library, and Google Scholar search engine. The Persian and the English languages were used as the filter in national and international databases, respectively. Medical Subject Headings (MeSH) terms was used to controlling comprehensive vocabulary. The search terms were conducted without time limitation till January 01, 2019.

Results

The prevalence of LTBI in Iranian’s HCWs, based on the PPD test was 27.13% [CI95%: 18.64–37.7]. The highest prevalence of LTBI in Iranian’s HCWs were estimated 41.4% [CI95%: 25.4–59.5] in the north, and 33.8% [CI95%: 21.1–49.3] in the west. The lowest prevalence of LTBI was evaluated 18.2% [CI95%: 3.4–58.2] in the south of Iran. The prevalence of LTBI in Iranian’s HCWs who had work-experience more than 20 years old were estimated 20.49% [CI95%: 11–34.97]. In the PPD test, the prevalence of LTBI in Iranian’s HCWs who had received the Bacille Calmette–Guérin (BCG) was estimated 15% [CI95%: 3.6–47.73]. While, in the QFT, the prevalence of LTBI in Iranian’s HCWs in non-vaccinated was estimated 25.71% [CI95%: 13.96–42.49].

Conclusions

This meta-analysis shows the highest prevalence of LTBI in Iranian’s HCWs in the north and the west probably due to neighboring countries like Azerbaijan and Iraq, respectively. It seems that Iranian’s HCWs have not received the necessary training to prevent of TB. We also found that BCG was not able to protect Iranian’s HCWs from TB infections, completely.

Tests for latent tuberculosis in candidates for solid organ transplantation: A systematic review and meta-analysis

Reactivation of latent tuberculosis following solid organ transplantation has serious consequences for the recipient. The most useful diagnostic test for latent TB is not clear. We conducted a systematic review and meta-analysis to assess the relative test performance of interferon gamma release assays (IGRAs) and the tuberculin skin test (TST) in people undergoing solid organ transplantation. The clinical or radiological risk factors were used as the proxy reference standard. Test performance was expressed as an odd ratio (OR). We identified 24 studies (N = 7811), 12 studies compared IGRAs with TST directly, nine studies evaluated only TST and three studies only IGRAs. Direct comparison between tests and clinical risk factors indicated both tests were strongly associated with the presence of clinical risk factors for TB (TST: OR 3.17; 95%CI 1.55-6.48, IGRA: OR 2.78; 95%CI 1.55-5.01), and radiological evidence of past TB (TST: OR 3.26; 95%CI 1.85-5.73, IGRA: OR 3.85; 95%CI 2.16-6.86). Relative comparison indicated IGRAs positivity was more strongly associated with presence of radiological evidence of TB than TST (relative OR: 3.24; 95%CI 1.10-9.56). While there is no strong evidence in supporting use of IGRAs over TST for diagnosing latent TB, IGRAs positivity is more associated with the presence of radiological evidence of previous TB.