Tuberculosis screening among HIV-infected patients: tuberculin skin test vs. interferon-gamma release assay

Knowledge and Attitudes About Screening and Preventive Treatment of Latent Tuberculosis Infection Among Patients with Rheumatic Diseases in Beijing, China

Objective

Tuberculosis preventive treatment (TPT) is an important strategy for tuberculosis (TB) control. Rheumatic diseases (RD) patients are at high risk for active TB development. More researches are needed in terms of patient compliance in clinical practice. This study aims to explore the potential difficulties and obstacles in latent tuberculosis infection (LTBI) screening and TPT in RD patients.

Methods

Convenience sampling was used to recruit RD outpatients who had indications for LTBI screening and TPT. All participants were given questionnaires on knowledge and attitudes regarding screening and preventive treatment of LTBI.

Results

Of the 200 RD patients, most people were aware that they were at increased risk of ATB due to their rheumatic disease and knew that TB was curable. The main association with willingness to have screening for LTBI was tertiary education (P = 0.013). The main association with willingness to take treatment for LTBI was a sense of personal risk and belief that the treatment would reduce risk of ATB (P < 0.001). More than half of the people surveyed could not accept taking 6 or more pills per day, while more than half of the patients could tolerate a treatment course of 9 months or longer. Most (65.4%) preferred their own rheumatologists to initiate treatment.

Conclusion

Educating RD patients about their individual risks of TB and the side effects of treatment, and educating/empowering rheumatologists to discuss these aspects with their patients and to offer LTBI screening and treatment, may help improve patients' compliance with LTBI screening and TPT.

A Literature Review on the Adherence to Screening Guidelines for Latent Tuberculosis Infection Among Persons Living With HIV

Human immunodeficiency virus (HIV) infection increases the risk of reactivation of latent tuberculosis infection (LTBI). Although antiretroviral therapy decreases the progression of LTBI to tuberculosis disease (TBD), persons living with HIV (PLHIV) still have higher risk of TBD compared to the general population. LTBI screening is recommended for all newly diagnosed PLHIV to prevent TBD. However, several studies from low TBD incidence countries have reported sub-optimal implementation of these guidelines. This review aims to assess published studies on adherence to LTBI screening among PLHIV by identifying factors and determinants that affect the implementation of LTBI screening among PLHIV in low TBD incidence countries. Electronic databases were used to search for articles describing the adherence to LTBI screening guidelines. Fourteen studies were included in the final review. Ten studies assessed the frequency of PLHIV getting LTBI screening, and 4 studies assessed the compliance of health care providers in implementing the guidelines. PLHIV who were screened for LTBI ranged from 22.4% to 85%, of which 0.8% to 25.6% had positive results. Only 20% to 57.4% of surveyed physicians implemented the guidelines. Country of birth was an independent predictor of receiving LTBI screening. LTBI screening guidelines are inconsistently performed resulting in missed opportunities for TBD prevention. A comprehensive screening policy involving testing all PLHIV may be the best approach, rather than a targeted approach testing foreign-born individuals only. This will minimize missing domestic cases that can worsen disparity in HIV and tuberculosis infection among minority groups, including Asians, Native Hawaiians, and Pacific Islanders.

Single-Cell Transcriptomics of Mtb/HIV Co-Infection

Tuberculosis (TB) and Human Immunodeficiency Virus (HIV) co-infection continues to pose a significant healthcare burden. HIV co-infection during TB predisposes the host to the reactivation of latent TB infection (LTBI), worsening disease conditions and mortality. There is a lack of biomarkers of LTBI reactivation and/or immune-related transcriptional signatures to distinguish active TB from LTBI and predict TB reactivation upon HIV co-infection. Characterizing individual cells using next-generation sequencing-based technologies has facilitated novel biological discoveries about infectious diseases, including TB and HIV pathogenesis. Compared to the more conventional sequencing techniques that provide a bulk assessment, single-cell RNA sequencing (scRNA-seq) can reveal complex and new cell types and identify more high-resolution cellular heterogeneity. This review will summarize the progress made in defining the immune atlas of TB and HIV infections using scRNA-seq, including host-pathogen interactions, heterogeneity in HIV pathogenesis, and the animal models employed to model disease. This review will also address the tools needed to bridge the gap between disease outcomes in single infection vs. co-infection. Finally, it will elaborate on the translational benefits of single-cell sequencing in TB/HIV diagnosis in humans.

Tuberculin skin test versus QuantiFERON-TB gold in-tube for latent tuberculosis screening in people living with HIV in a resource-limited setting

OBJECTIVE

To compare QuantiFERON-TB Gold-in-Tube (QFT) and tuberculin skin test (TST) in the diagnosis of latent tuberculosis infection (LTBI) among people living with HIV (PLWHIV).

METHODS

A cross-sectional study was carried out between 2017-2018. Tuberculin skin test and QFT were performed and their concordance was measured. The gold standard for LTBI was defined as positivity to any of the tests. A logistic regression model was carried out to predict the QFT result in patients with a negative TST.

RESULTS

A total of 510 PLWHIV were included, with 409 (80.2%) being male. The mean age of the patients was 41.3 ± 11.8 years. The median time since HIV diagnosis was 5 years (IQR 2-10), with a median CD4⁺ count of 541 (IQR 340-757) cells/mm³. Overall, 20 patients had an isolated TST+, 22 an isolated QFT+ and 15 had both positive. Concordance between tests showed a kappa coefficient of .37. Overcrowding was the only predictor for a positive QFT after a negative TST (p = .003).

CONCLUSION

There was fair agreement between tests in PLWHIV. In conditions of limited access to QTF, a TST-based strategy could be considered, with sequential use of QTF in high-risk patients with a negative result, especially those who live in overcrowded conditions.

Testing and treatment for latent tuberculosis infection in people living with HIV and substance dependence: a prospective cohort study

OBJECTIVE

To quantify the proportion of people living with HIV (PLWH) with other tuberculosis (TB) risk factors that completed the latent tuberculosis infection (LTBI) care cascade and describe factors associated with attrition. The care cascade was defined as follows: (1) receipt of an LTBI test and result, (2) initiation of LTBI treatment and (3) completion of LTBI treatment.

DESIGN

Prospective cohort study.

SETTING

Reactivation of LTBI remains a large source of active TB disease in the USA. PLWH and those who use substances are at greater risk and are harder to engage and retain in care.

PARTICIPANTS

Participants enrolled in a Boston cohort of PLWH from 2012 to 2014.

PRIMARY AND SECONDARY OUTCOME MEASURES

Our primary outcome was the number and proportion of participants who completed each stage of the cascade and the factors associated with completing each stage. Our secondary outcomes were differences between participants tested with an interferon gamma release assay (IGRA) versus tuberculin skin test and differences between participants who tested positive versus negative for LTBI.

RESULTS

Only 189 of 219 (86.3%) participants completed testing. Five of the 11 with LTBI initiated and three completed treatment. Participants tested with an IGRA were more likely to complete testing (OR 3.87, 95% CI 1.05 to 14.30) while among participants successfully tested, being foreign-born was associated with a positive test result (OR 3.95; 95% CI 1.13 to 13.77).

CONCLUSIONS

Although the majority completed LTBI testing, our findings warrant further investigation in a larger cohort to better understand factors that lead to suboptimal treatment initiation and completion in a low-burden country.

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.

Lack of latent tuberculosis (TB) screening and delay in anti-retroviral therapy initiation in HIV-TB co-infection: an 11-year study in an intermediate TB-burden country

OBJECTIVES

To examine the prevalence and characteristics of HIV-tuberculosis (TB) co-infected patients in Singapore, an intermediate TB-burden country.

METHODS

Retrospective data across 11 years was obtained from the National University Hospital (NUH), a quaternary hospital and the National Centre for Infectious Diseases (NCID), the national HIV center.

RESULTS

From December 2005 to December 2016, 4015 HIV-infected patients were managed at NUH and NCID, of whom, respectively, 48 and 272 were diagnosed with active TB disease. Only 2 patients (0.6%) were screened for latent TB infection on HIV diagnosis. Mean CD4 count at TB diagnosis was 125.0 ± 153.9 cells/mm³. More patients with HIV diagnosed ≥6 weeks before TB (41%) were associated with CD4 counts >200 cells/mm³ than patients with TB diagnosed ≥6 weeks before HIV (2%). Of 124 (38.6%) HIV-TB patients with CD4 count ≤50 cells/mm³, only 18 (14.2%) started anti-retroviral therapy (ART) in <2 weeks. Of patients with pulmonary TB, 33.5% had normal chest x-ray.

CONCLUSIONS

Latent TB infection screening in HIV-infected patients is low, and ART initiation is delayed in HIV-TB patients with CD4 ≤50 cells/mm³. Pulmonary TB patients with HIV can be infectious despite normal chest x-ray. Clinical practices can be further improved to benefit HIV-TB patients.

The latent tuberculosis cascade-of-care among people living with HIV: A systematic review and meta-analysis

BACKGROUND

Tuberculosis preventive therapy (TPT) reduces TB-related morbidity and mortality in people living with HIV (PLHIV). Cascade-of-care analyses help identify gaps and barriers in care and develop targeted solutions. A previous latent tuberculosis infection (LTBI) cascade-of-care analysis showed only 18% of persons in at-risk populations complete TPT, but a similar analysis for TPT among PLHIV has not been completed. We conducted a meta-analysis to provide this evidence.

METHODS AND FINDINGS

We first screened potential articles from a LTBI cascade-of-care systematic review published in 2016. From this study, we included cohorts that reported a minimum of 25 PLHIV. To identify new cohorts, we used a similar search strategy restricted to PLHIV. The search was conducted in Medline, Embase, Health Star, and LILACS, from January 2014 to February 2021. Two authors independently screened titles and full text and assessed risk of bias using the Newcastle-Ottawa Scale for cohorts and Cochrane Risk of Bias for cluster randomized trials. We meta-analyzed the proportion of PLHIV completing each step of the LTBI cascade-of-care and estimated the cumulative proportion retained. These results were stratified based on cascades-of-care that used or did not use LTBI testing to determine eligibility for TPT. We also performed a narrative synthesis of enablers and barriers of the cascade-of-care identified at different steps of the cascade. A total of 71 cohorts were included, and 70 were meta-analyzed, comprising 94,011 PLHIV. Among the PLHIV included, 35.3% (33,139/94,011) were from the Americas and 29.2% (27,460/94,011) from Africa. Overall, 49.9% (46,903/94,011) from low- and middle-income countries, median age was 38.0 [interquartile range (IQR) 34.0;43.6], and 65.9% (46,328/70,297) were men, 43.6% (29,629/67,947) were treated with antiretroviral therapy (ART), and the median CD4 count was 390 cell/mm3 (IQR 312;458). Among the cohorts that did not use LTBI tests, the cumulative proportion of PLHIV starting and completing TPT were 40.9% (95% CI: 39.3% to 42.7%) and 33.2% (95% CI: 31.6% to 34.9%). Among cohorts that used LTBI tests, the cumulative proportions of PLHIV starting and completing TPT were 60.4% (95% CI: 58.1% to 62.6%) and 41.9% (95% CI:39.6% to 44.2%), respectively. Completion of TPT was not significantly different in high- compared to low- and middle-income countries. Regardless of LTBI test use, substantial losses in the cascade-of-care occurred before treatment initiation. The integration of HIV and TB care was considered an enabler of the cascade-of-care in multiple cohorts. Key limitations of this systematic review are the observational nature of the included studies, potential selection bias in the population selection, only 14 cohorts reported all steps of the cascade-of-care, and barriers/facilitators were not systematically reported in all cohorts.

CONCLUSIONS

Although substantial losses were seen in multiple stages of the cascade-of-care, the cumulative proportion of PLHIV completing TPT was higher than previously reported among other at-risk populations. The use of LTBI testing in PLHIV in low- and middle-income countries was associated with higher proportion of the cohorts initiating TPT and with similar rates of completion of TPT.

Rats sniff out pulmonary tuberculosis from sputum: a diagnostic accuracy meta-analysis

In Sub-Saharan Africa, African giant pouched rats (Cricetomys gambianus) are trained to identify TB patients by smelling sputum. We conducted a systematic review and meta-analysis of the data to see if this novel method is comparable to traditional laboratory screening and detection methods like Ziehl–Neelsen stain-based assays (ZN) and bacterial culture. The search and data processing strategy is registered at PROSPERO (CRD42019123629). Medline via PubMed, EMBASE, Web of Science, and Cochrane Library databases were systematically searched for the keywords “pouched rat” and “tuberculosis”. Data from 53,181 samples obtained from 24,600 patients were extracted from seven studies. Using sample-wise detection, the sensitivity of the studies was 86.7% [95% CI 80.4–91.2%], while the specificity was 88.4% [95% CI 79.7–93.7%]. For patient-wise detection, the sensitivity was 81.3% [95% CI 64.0–91.4%], while the specificity was 73.4% [95% CI 62.8–81.9%]. Good and excellent classification was assessed by hierarchical summary receiver-operating characteristic analysis for patient-wise and sample-wise detections, respectively. Our study is the first systematic review and meta-analysis of the above relatively inexpensive and rapid screening method. The results indicate that African giant pouched rats can discriminate healthy controls from TB individuals by sniffing sputum with even a higher accuracy than a single ZN screening.

Latent Tuberculosis and HIV Infection

Purpose of Review

Tuberculosis is the number one infectious killer of people with HIV worldwide, but it can be both prevented and treated. Prevention of tuberculosis by screening for and treating latent tuberculosis infection (LTBI), along with the initiation of antiretroviral therapy (ART), is the key component of HIV care.

Recent Findings

While access to ART has increased worldwide, uptake and completion of LTBI treatment regimens among people living with HIV (PWH) are very poor. Concomitant TB-preventive therapy and ART are complex because of drug–drug interactions, but these can be managed. Recent clinical trials of shorter preventive regimens have demonstrated safety and efficacy in PWH with higher completion rates. More research is needed to guide TB-preventive therapy in children and in pregnant women, and for drug-resistant TB (DR-TB).

Summary

Antiretroviral therapy and tuberculosis-preventive treatment regimens can be optimized to avoid drug–drug interactions, decrease pill burden and duration, and minimize side effects in order to increase adherence and treatment completion rates among PWH and LTBI.

A longitudinal study on latent TB infection screening and its association with TB incidence in HIV patients

Latent TB infection (LTBI) in HIV patients, its treatment, and immunological recovery following highly active antiretroviral therapy (HAART) could interact and impact TB disease progression. We aim to examine the factors associated with LTBI and TB disease development among HIV patients. Longitudinal clinical and laboratory data were accessed from the largest HIV specialist clinic in Hong Kong, where HAART and yearly LTBI screening are routinely provided for HIV patients. Between 2002 and mid-2017, among 2079 HIV patients with 14119 person-years (PY) of follow-up, 32% of LTBI screened patients (n = 1740) were tested positive. The overall TB incidence was 1.26/100 PY from HIV diagnosis to HAART initiation, falling to 0.37/100 PY. A lower risk of TB disease progression was associated with local residence, Chinese ethnicity, negative baseline LTBI result, being on HAART, LTBI treatment, higher baseline CD4 and CD4/CD8 ratio. A positive test at baseline, but not subsequent testing results, was significantly associated with TB disease development. Baseline LTBI screening is an important strategy for identifying HIV patients at risk of TB disease progression. Routine repeat LTBI screening on an annual basis might not give additional benefits to patients on HAART with good immunological responses. Such practice should require re-evaluation.