Latent and subclinical tuberculosis in HIV infected patients: a cross-sectional study

Risk of tuberculosis after initiation of antiretroviral therapy among persons with HIV in Europe

OBJECTIVES

Tuberculosis (TB) risk after initiation of antiretroviral treatment (ART) is not well described in a European setting, with an average TB incidence of 25/105 in the background population.

METHODS

We included all adult persons with HIV starting ART in the RESPOND cohort between 2012 and 2020. TB incidence rates (IR) were assessed for consecutive time intervals post-ART initiation. Risk factors for TB within 6 months from ART initiation were evaluated using Poisson regression models.

RESULTS

Among 8441 persons with HIV, who started ART, 66 developed TB during 34,239 person-years of follow-up (PYFU), corresponding to 1.87/1000 PYFU (95% confidence interval [CI]: 1.47-2.37). TB IR was highest in the first 3 months after ART initiation (14.41/1000 PY (95%CI 10.08-20.61]) and declined at 3-6, 6-12, and >12 months post-ART initiation (5.89 [95%CI 3.35-10.37], 2.54 [95%CI 1.36-4.73] and 0.51 [95%CI 0.30-0.86]), respectively. Independent risk factors for TB within the first 6 months after ART initiation included follow-up in Northern or Eastern Europe region, African origin, baseline CD4 count <200 cells/mm3, HIV RNA >100,000 copies/mL, injecting drug use and heterosexual transmission.

CONCLUSIONS

TB IR was highest in the first 3 months post-ART initiation and was associated with baseline risk factors, highlighting the importance of thorough TB risk assessment at ART initiation.

Present outlooks on the prevalence of minimal and subclinical tuberculosis and current diagnostic tests: A systematic review and meta-analysis

BACKGROUND

Tuberculosis (TB) is a major global health issue, particularly in its minimal and subclinical forms, which often go undetected and contribute to transmission. Accurate prevalence assessment of these forms and the effectiveness of diagnostic tests are crucial for improving TB control, especially in high-risk populations such as those with HIV.

OBJECTIVES

This study aimed to determine the prevalence of minimal and subclinical TB and evaluate the positivity rates of current diagnostic tests.

METHODS

We conducted a meta-analysis of studies published from January 2000 to December 2022. Prevalence rates and diagnostic test results, including sputum culture, smear microscopy, TST/IGRA, and chest X-ray, were analyzed, with pooled prevalence calculated and comparisons made between geographic regions.

RESULTS

Minimal TB prevalence ranged from 0.9 % to 22.9 % in the general population, while subclinical TB prevalence was 0.05 % to 0.64 %, and 1.57 % to 14.63 % among individuals with HIV. The overall pooled prevalence of minimal TB was 7 % (95 % CI: 5-9 %), with higher rates in Asia (8 %, 95 % CI: 5-12 %) compared to Africa (6 %, 95 % CI: 4-8 %). Subclinical TB had a pooled prevalence of 0.2 % (95 % CI: 0.2-0.3 %) overall and 52 % (95 % CI: 46-58 %) among TB cases, with higher rates in Asia (60 %) compared to Africa (44 %). Diagnostic test positivity was 77 % (sputum culture), 15 % (smear microscopy), 64 % (TST/IGRA), and 53 % (chest X-ray).

CONCLUSIONS

This study reveals significant variability in the prevalence of minimal and subclinical TB. The findings highlight the need for improved diagnostic methods to reduce undetected cases, especially in high-risk populations.

Screening for Latent Tuberculosis Infection in People Living with HIV: TUBHIVIT Project, a Multicenter Italian Study

BACKGROUND

The coexistence of HIV infection and latent tuberculosis infection (LTBI) presents a significant public health concern due to the increased risk of tuberculosis (TB) reactivation and progression to active disease. The multicenter observational cohort study, TUBHIVIT, conducted in Italy from 2017 to 2023, aimed to assess the prevalence of LTBI among people living with HIV (PLHIV) and their outcomes following LTBI screening and therapy initiation.

METHODS

We performed a prospective study in five referral centers for HIV care in Italy. PLHIV who consented Tto participate underwent QuantiFERON-TB Gold Plus and clinical, microbiological, and radiological assessments to exclude subclinical tuberculosis, as opportune. PLHIV diagnosed with LTBI who started chemoprophylaxis were followed until the end of therapy.

RESULTS

A total of 1105 PLHIV were screened for LTBI using the QuantiFERON-TB Gold Plus test, revealing a prevalence of 3.4% of positive results (38/1105). Non-Italy-born individuals exhibited a significantly higher likelihood of testing positive. Thirty-one were diagnosed with LTBI, 1 showed active subclinical TB, and 6 were lost to follow-up before discriminating between latent and active TB. Among the PLHIV diagnosed with LTBI, 83.9% (26/31) started chemoprophylaxis. Most individuals received 6-9 months of isoniazid-based therapy. Of the 26 PLHIV commencing chemoprophylaxis, 18 (69.2%) completed the therapy, while 3 discontinued it and 5 were still on treatment at the time of the analysis. Adverse events were observed in two cases, while in one case the patient refused to continue the treatment.

Screening for tuberculosis infection and effectiveness of preventive treatment among people with HIV in low-incidence settings

OBJECTIVE

To determine the yield of screening for latent tuberculosis infection (LTBI) among people with HIV (PWH) in low tuberculosis (TB) incidence countries (<10 TB cases per 100 000 persons).

DESIGN

A systematic review and meta-analysis were performed to assess prevalence and predictive factors of LTBI, rate of TB progression, effect of TB preventive treatment (TPT), and numbers needed to screen (NNS).

METHODS

PubMed and Cochrane Library were searched for studies reporting primary data, excluding studies on active or paediatric TB. We extracted LTBI cases, odds ratios, and TB incidences; pooled estimates using a random-effects model; and used the Newcastle-Ottawa scale for bias.

RESULTS

In 51 studies with 65 930 PWH, 12% [95% confidence interval (CI) 10-14] had a positive LTBI test, which was strongly associated with origin from a TB-endemic country [odds ratio (OR) 4.7] and exposure to TB (OR 2.9). Without TPT (10 629 PWH), TB incidence was 28/1000 person-years (PY; 95% CI 12-45) for LTBI-test positive versus 4/1000 PY (95% CI 0-7) for LTBI-test-negative individuals. Among 625 PWH (1644 PY) receiving TPT, 15 developed TB (6/1000 PY). An estimated 20 LTBI-positive individuals would need TPT to prevent one case of TB, and numbers NNS to detect LTBI or prevent active TB varied according to a-priori risk of LTBI.

CONCLUSION

The relatively high prevalence of LTBI among PWH and the strong correlation with origin from a TB-endemic country support risk-stratified LTBI screening strategies for PWH in low-incidence countries and treating those who test positive.

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.

The impact, effectiveness and outcomes of targeted screening thresholds for programmatic latent tuberculosis infection testing in HIV

BACKGROUND

Screening and treatment for latent tuberculosis infection (LTBI) are key for TB control. In the UK, the National Institute for Health and Care Excellence (NICE) and the British HIV Association (BHIVA) give conflicting guidance on which groups of people with HIV (PWH) should be screened, and previous national analysis demonstrated heterogeneity in how guidance is applied. There is an urgent need for a firmer clinical effectiveness evidence base on which to build screening policy.

METHODS

We conducted a systematic, programmatic LTBI-screening intervention for all PWH receiving care in Leicester, UK. We compared yields (percentage IGRA positive) and number of tests required when applying the NICE and BHIVA testing strategies, as well as strategies targeting screening by TB incidence in patients' countries of birth.

RESULTS

Of 1053 PWH tested, 118 were IGRA-positive (11.2%). Positivity was associated with higher TB incidence in country-of-birth [adjusted odds ratio, 50-149 cases compared with <50 cases/100 000: 11.6; 95% confidence interval (CI) 4.79-28.10)]. There was high testing uptake (1053/1069, 98.5%). Appropriate chemoprophylaxis was commenced in 100 of 117 (85.5%) patients diagnosed with LTBI, of whom 96 of 100 (96.0%) completed treatment. Delivering targeted testing to PWH from countries with TB incidence greater than 150 per 100 000 population or any sub-Saharan African country, would have correctly identified 89.8% of all LTBI cases while cutting tests required by 46.1% compared with NICE guidance, performing as well as BHIVA 2018 guidance.

CONCLUSION

Targeting screening to higher risk PWH increases yield and reduces the number requiring testing. Our proposed 'PWH-LTBI streamlined guidance' offers a simplified approach, with the potential to improve national LTBI-screening implementation.

Latent tuberculosis screening and treatment in HIV: highly acceptable in a prospective cohort study

Background

People living with HIV (PLWH) are at increased risk of re-activation of latent tuberculosis infection (LTBI). Although UK and international guidelines identify this group as a priority for LTBI screening and treatment, data on attitudes of PLWH to this policy recommendation are lacking.

Methods

A five-point, Likert-style questionnaire was administered to PLWH to assess views and intentions towards accepting LTBI screening and treatment. Subsequent interferon-γ release assay (IGRA) testing was offered, and chemoprophylaxis if required. Influencing demographic and psychological associations with planned, and actual, testing and treatment uptake were assessed using multivariable logistic regression.

Results

444 out of 716 (62%) patients responded. 417 out of 437 (95.4%) expressed intention to accept LTBI testing. The only significant association was the perceived importance of testing to the individual (adjusted odds ratio (aOR) 8.98, 95% CI 2.55–31.67). 390 out of 393 (99.2%) accepted appropriate IGRA screening; 41 out of 390 (10.5%) were positive. 397 out of 431 (92.1%) expressed intention to accept chemoprophylaxis, associated with perceived importance of treatment (aOR 3.52, 95% CI 1.46–8.51), a desire to have treatment for LTBI (aOR 1.77, 95% CI 0.99–3.15) and confidence in taking treatment (aOR 3.77, 95% CI 1.84–7.72). Of those offered chemoprophylaxis, 36 out of 37 (97.3%) accepted and 34 out of 36 (94.4%) completed treatment. There were no correlates with actual screening acceptance.

Conclusions

LTBI is common amongst PLWH, highlighting the importance of robust screening and treatment programmes. This study shows that screening and treatment for LTBI is highly acceptable to PLWH and provides strong, objective evidence for policy-makers developing guidelines in this cohort.

This detailed exploration of the views of people living with HIV in the UK through a prospective questionnaire cohort study is the first of its kind in the published literature, and shows that latent TB screening and treatment is overwhelmingly supportedhttps://bit.ly/3HmhmRy

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.

Diagnosis of latent tuberculosis among HIV infected patients in Ilorin, Nigeria using tuberculin skin test and interferon gamma release assay

Introduction

Latent Tuberculosis Infection (LTBI) screening is recommended for individuals with a known risk factor for progression to active disease especially in the setting of HIV infection. This will ensure early diagnosis and prompt treatment. The purpose of our study was to compare tuberculin skin test (TST) with Interferon Gamma Release Assay (IGRA) in the diagnosis of LTBI among patients with known HIV infection at University of Ilorin Teaching Hospital (UITH), Ilorin.

Methods

this was a hospital based cross-sectional study at the Highly Active Antiretroviral therapy (HAART) Clinic and medical wards of the University of Ilorin Teaching Hospital, Ilorin, Nigeria. A total of 282 consenting patients with HIV infection were recruited. Sociodemographic and clinical information was obtained using a well-structured questionnaire. The screening for LTBI was done using Tuberculin skin test (TST) and Interferon Gamma release assay (IGRA).

Results

the prevalence of LTBI among HIV infected patients was 40.6% and 53.1% using TST and QFT-IT respectively, while the overall prevalence considering positivity to either of the test was 66%. There was mild agreement (κ: 0.218) between TST and QFT-IT in the diagnosis of LTBI among patients with HIV infection. The association between CD4 count and TST was not statistically significant (p value = 0.388) but there was strong association between CD4 cell count and QFT results (p = 0.001).

Conclusion

the prevalence of LTBI is quite high among patients with HIV infection in our locality. There is a need to encourage screening of at-risk individuals to forestall the morbidity and mortality associated with TB in this population.

Cost effectiveness of testing HIV infected individuals for TB in a low TB/HIV setting

OBJECTIVES

Guidelines recommend routine testing for latent TB infection (LTBI) in people living with HIV. However there are few cost-effectiveness studies to justify this in contemporary high resource, low TB/HIV incidence settings. We sought to assess the uptake, yield and cost-effectiveness of testing for latent and active TB.

METHODS

Adults attending an ambulatory HIV clinic in London, UK were prospectively recruited by stratified selection and tested for TB infection using symptom questionnaires, chest radiograph (CXR), tuberculin skin test (TST), T-Spot.TB and induced sputum. From this, 30 testing strategies were compared in a cost-effectiveness model including probabilistic sensitivity analysis using Monte Carlo simulation.

RESULTS

219 subjects were assessed; 95% were using antiretroviral therapy (ART). Smear negative, culture positive TB was present in 0.9% asymptomatic subjects, LTBI in 9%. Only strategies testing those from subSaharan Africa with a TST or interferon gamma release assay (IGRA) with or without CXR, or testing those from countries with a TB incidence of >40/100,000 with TST alone were cost-effective using a £30,000/QALY threshold.

CONCLUSIONS

Cost-effectiveness analysis in an adult HIV cohort with high ART usage suggests there is limited benefit beyond routine testing for latent TB in people from high and possibly medium TB incidence settings.

Implementation of routine interferon-gamma release assay testing in a South London HIV cohort

Human immunodeficiency virus (HIV) infection is a major risk factor for the development of tuberculosis (TB). Although guidelines recommend that people with HIV from high TB incidence countries and those with risk factors are screened for latent TB infection (LTBI) using interferon-gamma release assays (IGRAs), this has not been widely implemented in the UK. We introduced universal LTBI screening using IGRAs at nurse-led induction clinics for patients newly presenting, transferring or re-presenting for HIV care and conducted a prospective audit from 1 January 2018 to 30 June 2019 to identify operational challenges as well as opportunities for TB prevention. Of the 223 patients, 17 had active or previously treated TB. Of the remaining 206 individuals who were eligible for IGRA testing, 78 (38%) were not tested due to logistical issues, failure to request the test or no induction visit taking place. Of the 128 (62%) individuals who were tested for LTBI, 3 (2.3%) had a positive IGRA, 4 (3.1%) an indeterminate result and 121 (94.5%) a negative result. All seven with positive/indeterminate tests were of African/Caribbean background, had CD4 cell counts >200 cells/mm3 and HIV RNA <400 copies/ml. Our audit suggests that universal LTBI screening was logistically challenging and provided few opportunities for TB prevention.

Latent tuberculosis infection and associated risk factors among people living with HIV and apparently healthy blood donors at the University of Gondar referral hospital, Northwest Ethiopia

Objective

Immuno-compromised individuals with latent tuberculosis infection (LTBI) are at an increased risk for tuberculosis reactivation compared with the general population. The aim of this study was to determine the prevalence of latent tuberculosis infection among people living with human immunodeficiency virus (PLWH) and apparently healthy blood donors. Human Immunodeficiency Virus positive individuals and for the purpose of comparison apparently healthy blood donors were enrolled. Blood sample was collected and tested for LTBI using QuantiFeron-TB Gold In-Tube assay (QFT-GIT) and CD4+ T cell count was determined by using BD FACS count.

Results

The overall prevalence of LTBI regardless of HIV status was 46%. The prevalence of LTBI among PLWH was 44% and that of blood donors 48%. ART naïve HIV positive patients were three times more likely to have LTBI than patients under ART treatment (P = 0.04). Data also showed statistically significant negative association between previous or current preventive INH therapy and LTBI among HIV positive cases (P = 0.005). The proportion of LTBI was slightly lower among HIV positive individuals than apparently healthy blood donors. Nevertheless, HIV positive individuals should be screened for LTBI and take INH prophylaxis.

Injecting drug use predicts active tuberculosis in a national cohort of people living with HIV

OBJECTIVES

Tuberculosis (TB) is common in people living with HIV, leading to worse clinical outcomes including increased mortality. We investigated risk factors for developing TB following HIV diagnosis.

DESIGN

Adults aged at least 15 years first presenting to health services for HIV care in England, Wales or Northern Ireland from 2000 to 2014 were identified from national HIV surveillance data and linked to TB surveillance data.

METHODS

We calculated incidence rates for TB occurring more than 91 days after HIV diagnosis and investigated risk factors using multivariable Poisson regression.

RESULTS

A total of 95 003 adults diagnosed with HIV were followed for 635 591 person-years; overall incidence of TB was 344 per 100 000 person-years (95% confidence interval 330-359). TB incidence was high for people who acquired HIV through injecting drugs [PWID; men 876 (696-1104), women 605 (365-945)] and black Africans born in high TB incidence countries [644 (612-677)]. The adjusted incidence rate ratio for TB amongst PWID was 4.79 (3.35-6.85) for men and 6.18 (3.49-10.93) for women, compared with MSM. The adjusted incidence rate ratio for TB in black Africans from high-TB countries was 4.27 (3.42-5.33), compared with white UK-born individuals. Lower time-updated CD4 cell count was associated with increased rates of TB.

CONCLUSION

PWID had the greatest risk of TB; incidence rates were comparable with those in black Africans from high TB incidence countries. Most TB cases in PWID were UK-born, and likely acquired TB through transmission within the United Kingdom. Earlier HIV diagnosis and quicker initiation of antiretroviral therapy should reduce TB incidence in these populations.

Knowledge about tuberculosis transmission and prevention and perceptions of health service utilization among index cases and contacts in Brazil: Understanding losses in the latent tuberculosis cascade of care

Introduction

Tuberculosis contacts are candidates for active and latent tuberculosis infection screening and eventual treatment. However, many losses occur in the different steps of the contacts’ cascade of care. Reasons for this are poorly understood.

Objective

To describe the different steps where losses in the contact cascade occur and to explore knowledge and attitudes regarding tuberculosis transmission/prevention and perceptions about tuberculosis services in order to understand the reasons for losses from the tuberculosis service users’ perspective.

Design

We collected routine data from the index case and contact registry books and from patients’ records to build the cascade of care of contacts in 12 health facilities in three Brazilian cities with high tuberculosis incidence rates. During a knowledge, attitudes and practices (KAP) survey, trained interviewers administered a semi-structured questionnaire to 138 index cases and 98 contacts.

Results

Most of the losses in the cascade occurred in the first two steps (contact identification, 43% and tuberculin skin testing placement, 91% of the identified contacts). Among KAP-interviewed contacts, 67% knew how tuberculosis is transmitted, 87% knew its key symptoms and 81% declared they would take preventive therapy if prescribed. Among KAP-interviewed index cases, 67% knew they could spread tuberculosis, 70% feared for the health of their families and 88% would like their family to be evaluated in the same services.

Conclusion

Only a small proportion of contacts are evaluated for active and latent tuberculosis, despite their—and their index cases’—reasonable knowledge, positive attitudes towards prevention and satisfaction with tuberculosis services. In these services, education of service users would not be a sufficient solution. Healthcare workers’ and managers’ perspective, not explored in this study, may bring more light to this subject.

Screening and treatment of latent tuberculosis infection among HIV-infected patients in resource-rich settings

Current international guidelines recommend screening and treatment of latent tuberculosis (TB) infection in HIV-infected patients in all settings. The main factors affecting the risk of TB in HIV-infected patients include the level of immunosuppression, coverage of antiretroviral therapy and local TB burden. In resource-rich settings where antiretroviral therapy is more accessible and HIV-infected patients are expected to be diagnosed at an earlier stage, local TB burden remains a key factor on their risk of TB. This article reviewed the epidemiology of latent TB infection among the adult HIV-infected patients, and the use and benefit of screening and treatment of latent TB infection in resource-rich settings in the past decade. While such practice should be continued in countries with medium or high TB burden, targeted screening and treatment only for HIV-infected patients with additional risk factors for TB might be a more practical option in resource-rich countries with low TB burden.

The cascade of care in diagnosis and treatment of latent tuberculosis infection: a systematic review and meta-analysis

BACKGROUND

WHO estimates that a third of the world's population has latent tuberculosis infection and that less than 5% of those infected are diagnosed and treated to prevent tuberculosis. We aimed to systematically review studies that report the steps from initial tuberculosis screening through to treatment for latent tuberculosis infection, which we call the latent tuberculosis cascade of care. We specifically aimed to assess the number of people lost at each stage of the cascade.

METHODS

We did a systematic review and meta-analysis of study-level observational data. We searched MEDLINE (via OVID), Embase, and Health Star for observational studies, published between 1946 and April 12, 2015, that reported primary data for diagnosis and treatment of latent tuberculosis infection. We did meta-analyses using random and fixed effects analyses to identify percentages of patients with latent tuberculosis infection completing each step in the cascade. We also estimated pooled proportions in subgroups stratified by different characteristics of interest to assess risk factors for losses.

RESULTS

We identified 58 studies, describing 70 distinct cohorts and 748 572 people. Steps in the cascade associated with greater losses included completion of testing (71·9% [95% CI 71·8-72·0] of people intended for screening), completion of medical evaluation (43·7% [42·5-44·9]), recommendation for treatment (35·0% [33·8-36·4]), and completion of treatment if started (18·8% [16·3-19·7]). Steps with fewer losses included receiving test results, referral for evaluation if test positive, and accepting to start therapy if recommended. Factors associated with fewer losses were immune-compromising medical indications, being part of contact investigations, and use of rifamycin-based regimens.

INTERPRETATION

We identify major losses at several steps in the cascade of care for latent tuberculosis infection. Improvements in management of latent tuberculosis will need programmatic approaches to address the losses at each step in the cascade.

FUNDERS

Canadian Institutes of Health Research.

Diagnosing active and latent tuberculosis among Iranian HIV-infected patients

OBJECTIVE

To screen for Tuberculosis (TB) in human immunodeficiency virus (HIV) people in an effort to improve early TB diagnosis and reduce TB transmission.

METHODS

A prospective study was conducted on adult HIV people from 2008 to 2011. Three samples of sputum, cell blood count, tuberculin skin test (TST) and chest X-ray were obtained from all patients. The characteristics of HIV patients with TB and HIV patients without TB were compared to each other.

RESULTS

Of the 154 HIV patients included, 58 (38%) had tuberculosis with a mean CD4 cell count of 68 cells/mm³ . Active TB was found in 56 (47%) patients with a history of intravenous drug use. Cough (OR = 3.1, 95% CI 1.2-7.79), positive TST (OR = 8.15, 95% CI 3.28-20.25) and an abnormal chest X-ray (OR = 5.1, 95% CI 1.84-14.2) were the predicting factors for detecting active TB among HIV patients. The sensitivity and specificity of a combination of any symptoms with chest X-ray, smear, TST or all of these were 96.5% and 86.5%, respectively. CD4 cell count <100 (OR = 2.67; 95% CI 1.23-5.78) and smoking (OR = 13.4; 95% CI 3.04-59.4) remained independently associated with TB in a multivariate analysis.

CONCLUSION

There was a high prevalence of TB within the HIV population. Screening for TB among these patients can be carried out at every clinic or health facility using a combination of symptoms, TST, chest X-ray and smear sample.

Interferon-Gamma Release Assays for the Diagnosis of Tuberculosis: A Systematic Review and Meta-analysis

BACKGROUND AND OBJECTIVE

We conducted a systematic review and meta-analysis to compare the accuracy of the interferon-gamma release assays (IGRAs) and the tuberculin skin test (TST) for the diagnosis of Mycobacterium tuberculosis infection.

METHODS

We systematically searched PubMed, Embase, Cochrane library, and Web of Science databases for relevant published studies in recent decades and calculated pooled estimated sensitivities, specificities, DOR, and SROC curve of the QFT-IT, T-SPOT and TST. Random-effects models were used to assess estimates from studies with significant heterogeneity. Moreover, area under the curve was used to evaluate the accuracy of the tests.

RESULTS

Overall, 9 studies for QFT-IT, 12 studies for T-SPOT, and 16 studies for TST involving 3586 participants were included in this analysis. We found that sensitivities of the QFT-IT, T-SPOT, and TST were respectively 0.842 (95 % CI 0.811-0.870), 0.840 (95 % CI 0.814-0.864), and 0.665 (CI 0.635-0.693); specificities were respectively 0.745 (95 % CI 0.715-0.775), 0.658 (95 % CI 0.621-0.693), and 0.633 (CI 0.605-0.661); positive likelihood ratios were respectively 3.652 (95 % CI 2.180-6.117), 2.196 (95 % CI 1.727-2.794), and 1.825 (95 % CI 1.351-2.464); negative likelihood ratios were respectively 0.212 (95 % CI 0.109-0.414), 0.246 (95 % CI 0.161-0.377), and 0.556 (95 % CI 0.385-0.804); the SROC curves were 19.205, 10.397, and 3.810.

CONCLUSIONS

The two IGRAs showed better performance than TST for the diagnosis of the tuberculosis. However, neither of them showed stability in the diagnosis of TB.

Decreasing cost effectiveness of testing for latent TB in HIV in a low TB incidence area

Testing for latent tuberculosis infection (LTBI) in HIV-infected persons in low tuberculosis (TB) incidence areas is often recommended. Using contemporary, clinical data, we report the yield and cost-effectiveness of testing all HIV attendees, two current UK strategies and no LTBI testing. Economic modelling was performed utilising 10-year follow up data from a large HIV clinical cohort. Outcomes were numbers of cases of active TB and incremental cost per quality-adjusted life year (QALY) gained. Between 2000 and 2010, 256 people were treated for TB/HIV co-infection. 72 (28%) occurred ≥3 months after HIV diagnosis and may have been prevented by LTBI testing. Between 2000 and 2005, the incremental cost per QALY gained for the British HIV Association (BHIVA) and UK National Institute of Care Excellence (NICE) strategies, and testing all clinic attendees was €6270, €6998 and €33,473, respectively. These rose to €9332, €32,564 and €74,067, respectively, between 2005 and 2010. Probabilistic sensitivity analysis suggested that at a threshold of €24,000 per additional QALY, the most cost-effective strategies would be NICE or testing all in 2000-2005 and BHIVA during 2005-2010. Both UK testing regimens missed cases but are cost-effective compared with no testing. Using recent data, they all became more expensive, suggesting that alternative or more targeted TB testing strategies must be considered.

HIV patients with latent tuberculosis living in a low-endemic country do not develop active disease during a 2 year follow-up; a Norwegian prospective multicenter study

BACKGROUND

Interferon-γ release assays (IGRA) serve as immunodiagnostics of tuberculosis (TB) infection to identify individuals with latent TB infection (LTBI) eligible for preventive anti-TB therapy. In this longitudinal study of HIV-infected LTBI patients we have observed for possible progression to active TB as well as evaluated repeated IGRA testing in a TB low-endemic setting.

METHODS

QuantiFERON TB-Gold In-tube® assay (QFT), TB-SPOT.TB® (TSPOT) and tuberculin skin test (TST) were performed on 298 HIV-patients recruited from seven out-patient clinics in Norway. Patients with active TB, LTBI and negative IGRA were followed with repeat QFTs and clinical evaluation over a period of 24 months.

RESULTS

Seven HIV-patients (median CD4 count 270; IQR 50-340) were diagnosed with active TB at inclusion, all IGRA positive. Sixty-four (21%) HIV-patients (median CD4 count 471; IQR 342-638) were diagnosed with LTBI and of these 39 (61%) received TB preventive treatment. Neither treated nor untreated HIV-infected LTBI patients developed active TB during the 24 months. At baseline, the median interferon-γ (INF-γ) level measured by QFT was 3.48 IU/ml (IQR 0.94-8.91 IU/ml) for treated LTBI compared to 1.13 IU/ml (IQR 0.47-4.25 IU/ml) for untreated LTBI patients (p = 0.029). The QFT reversion rates were 75% for active TB, 23% for treated LTBI and 44% for untreated LTBI, whereas the conversion rate for the non-TB group was 7% despite no new TB exposure. There was no significant difference in the trend of INF-γ levels over time between treated and untreated LTBI patients.

CONCLUSION

The prevalence of LTBI is high among HIV-patients, but the risk of developing active TB seems to be low in patients with high CD4 counts in this TB low-endemic setting. In several patients, especially with baseline IFN-γ levels close to cut-offs, the QFT tests reverted to negative independent of preventive anti-TB treatment indicating possibly false positive tests. This highlights the importance of defining reliable cut-offs for immunodiagnostic tests and deferring preventive therapy in selected patients. Randomized studies with longer follow-up time are needed to identify HIV-patients that would benefit from LTBI treatment in a TB low-endemic setting.

Comparison of two interferon-gamma release assays (QuantiFERON-TB Gold In-Tube and T-SPOT.TB) in testing for latent tuberculosis infection among HIV-infected adults

There is currently no ‘gold standard’ for diagnosis of latent tuberculosis infection (LTBI), and both the tuberculin skin test and interferon-gamma release assays (IGRAs) are used for diagnosis; the latter have a higher sensitivity than tuberculin skin tests for diagnosis of LTBI in HIV-infected individuals with lower CD4 counts. No evidence base exists for selection of IGRA methodology to identify LTBI among human immunodeficiency virus-infected patients in the UK. We prospectively evaluated two commercially available IGRA methods (QuantiFERON-TB Gold In Tube [QFG] and T-SPOT.TB) for testing LTBI among HIV-infected patients potentially nosocomially exposed to an HIV-infected patient with ‘smear-positive’ pulmonary tuberculosis. Among the exposed patients median CD4 count was 550 cells/µL; 105 (90%) of 117 were receiving antiretroviral therapy, of who 104 (99%) had an undetectable plasma HIV load. IGRAs were positive in 12 patients (10.3%); QFG positive in 11 (9.4%) and T-SPOT.TB positive in six (5.1%); both IGRAs were positive in five patients (4.3%). There was one indeterminate QFG and one borderline T-SPOT.TB result. Concordance between the two IGRAs was moderate (κ = 0.56, 95% confidence interval = 0.27–0.85). IGRAs were positive in only 4 (29%) of 14 patients with previous culture-proven tuberculosis. No patient developed tuberculosis during 20 months of follow-up.