The timing of tuberculosis after isoniazid preventive therapy among gold miners in South Africa: a prospective cohort study

Prioritizing persons deprived of liberty in global guidelines for tuberculosis preventive treatment

In this Policy Forum piece, Aditya Narayan and colleagues discuss the challenges and opportunities for tuberculosis preventive treatment in carceral settings.

Effect of different interventions for latent tuberculosis infections in China: a model-based study

BACKGROUND

Tuberculosis (TB) has a serious impact on people's health. China is one of 30 countries that has a high TB burden. As the currently decreasing speed of the incidence of TB, the WHO's goal of "End TB Strategy" is hard to achieve by 2035. As a result, a SEIR model that determines the impact of different tuberculosis preventive treatments (TPTs) in different age groups, and the effect of different interventions on latent TB infections (LTBIs) in China is developed.

METHODS

A Susceptible-Exposed-Infectious-Recovered (SEIR) model was established. Goodness-of-fit tests were used to assess model performance. Predictive analysis was used to assess the effect of different interventions on LTBIs and achieving the goals of the "End TB Strategy".

RESULTS

The Chi-square test indicated the model provided a good statistical fit to previous data on the incidence of TB (χ² = 0.3085, p > 0.999). The 1HP treatment regimen (daily rifapentine + isoniazid for 4 weeks) was most effective in reducing the number of TB cases by 2035. The model indicated that several strategies could achieve the 2035 target of the "End TB Strategy": completion of active case finding (ACF) for LTBI and TPT nation-wide within 5 years; completion of ACF for LTBIs and TPT within 2 years in high-incidence areas; completion of TPT in the elderly within 2 years; or introduction of a new vaccine in which the product of annual doses and vaccine efficiency in the three age groups above 14 years old reached 10.5 million.

CONCLUSION

The incidence of TB in China declined gradually from 2005 to 2019. Implementation of ACF for LTBIs and TPT nation-wide or in areas with high incidence, in the elderly, or administration of a new and effective vaccine could greatly reduce the number of TB cases and achieve the 2035 target of the "End TB Strategy" in China.

Prioritising attributes for tuberculosis preventive treatment regimens: a modelling analysis

BACKGROUND

Recent years have seen important improvements in available preventive treatment regimens for tuberculosis (TB), and research is ongoing to develop these further. To assist with the formulation of target product profiles for future regimens, we examined which regimen properties would be most influential in the epidemiological impact of preventive treatment.

METHODS

Following expert consultation, we identified 5 regimen properties relevant to the incidence-reducing impact of a future preventive treatment regimen: regimen duration, efficacy, ease-of-adherence (treatment completion rates in programmatic conditions), forgiveness to non-completion and the barrier to developing rifampicin resistance during treatment. For each regimen property, we elicited expert input for minimally acceptable and optimal (ideal-but-feasible) performance scenarios for future regimens. Using mathematical modelling, we then examined how each regimen property would influence the TB incidence reduction arising from full uptake of future regimens according to current WHO guidelines, in four countries: South Africa, Kenya, India and Brazil.

RESULTS

Of all regimen properties, efficacy is the single most important predictor of epidemiological impact, while ease-of-adherence plays an important secondary role. These results are qualitatively consistent across country settings; sensitivity analyses show that these results are also qualitatively robust to a range of model assumptions, including the mechanism of action of future preventive regimens.

CONCLUSIONS

As preventive treatment regimens against TB continue to improve, understanding the key drivers of epidemiological impact can assist in guiding further development. By meeting these key targets, future preventive treatment regimens could play a critical role in global efforts to end TB.

Effectiveness of a 6-Month Isoniazid on Prevention of Incident Tuberculosis Among People Living with HIV in Eritrea: A Retrospective Cohort Study

Introduction

A 6-month isoniazid as tuberculosis preventive therapy (TPT) for people living with HIV (PLHIV) was nationally introduced in Eritrea in 2014. However, its effectiveness in preventing tuberculosis (TB) and duration of protection was questioned by physicians. This study was, therefore, conducted to evaluate the impact of the isoniazid preventive therapy (IPT) primarily on the prevention of TB and duration of its protection in PLHIV.

Methods

A retrospective cohort study was conducted that selected all eligible PLHIV attending HIV care clinics in all national and regional referral hospitals in Eritrea. Data was collected from patients’ clinical cards using a structured data extraction sheet. The association between use of IPT and outcomes of interest was assessed using a Cox proportional hazard regression model and Kaplan–Meier curve.

Results

A total of 6803 patients were selected, which accounted for 75% of all PLHIV-accessing HIV care clinics in Eritrea. About 76% of patients were exposed to IPT while the remaining 24% were unexposed. The mean follow-up time was 4.9 years (SD 1.4). The incidence rate of TB was 1.7 and 10 cases per 1000 person-years in the exposed and unexposed, respectively. The unexposed had a higher risk of incident TB (adjusted hazard ratio [aHR] 3.75, 95% confidence interval [CI] 2.89, 6.13) and all-cause mortality (HR 2.41, 95% CI 1.85, 3.14) compared to the exposed. A Kaplan–Meier curve showed that the exposed group had a higher TB-free follow-up probability (98.8%) compared to the unexposed (95%) at 65 months of follow-up (p < 0.001). IPT protection decreased rapidly 6 months after isoniazid completion.

Conclusion

Use of a 6-month isoniazid as TPT was found to be effective in reducing incident TB in PLHIV-accessing HIV care clinics in Eritrea. However, the protection appeared to diminish soon, namely 6 months after completion of isoniazid, which warrants immediate attention from policy makers.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-022-00589-w.

Plasma host protein biomarkers correlating with increasing Mycobacterium tuberculosis infection activity prior to tuberculosis diagnosis in people living with HIV

BACKGROUND

Biomarkers correlating with Mycobacterium tuberculosis infection activity/burden in asymptomatic individuals are urgently needed to identify and treat those at highest risk for developing active tuberculosis (TB). Our main objective was to identify plasma host protein biomarkers that change over time prior to developing TB in people living with HIV (PLHIV).

METHODS

Using multiplex MRM-MS, we investigated host protein expressions from 2 years before until time of TB diagnosis in longitudinally collected (every 3-6 months) and stored plasma from PLHIV with incident TB, identified within a South African (SA) and US cohort. We performed temporal trend and discriminant analyses for proteins, and, to assure clinical relevance, we further compared protein levels at TB diagnosis to interferon-gamma release assay (IGRA; SA) or tuberculin-skin test (TST; US) positive and negative cohort subjects without TB. SA and US exploratory data were analyzed separately.

FINDINGS

We identified 15 proteins in the SA (n=30) and 10 in the US (n=24) incident TB subjects which both changed from 2 years prior until time of TB diagnosis after controlling for 10% false discovery rate, and were significantly different at time of TB diagnosis compared to non-TB subjects (p<0.01). Five proteins, CD14, A2GL, NID1, SCTM1, and A1AG1, overlapped between both cohorts. Furthermore, after cross-validation, panels of 5 - 12 proteins were able to predict TB up to two years before diagnosis.

INTERPRETATION

Host proteins can be biomarkers for increasing Mycobacterium tuberculosis infection activity/burden, incipient TB, and predict TB development in PLHIV.

FUNDING

NIH/NIAID AI117927, AI146329, and AI127173 to JMA.

The efficacy of isoniazid prophylaxis in renal transplant recipients in a high tuberculosis burden country

INTRODUCTION

Renal transplant recipients are at high risk of tuberculosis (TB). We started isoniazid (INH) prophylaxis of 1 year duration in all renal transplant recipients from April 2009. Our aim was to assess the incidence of TB on INH prophylaxis and its tolerability.

METHODS

This was a retrospective observational study. The files of renal transplant recipients from April 2009 to December 2011 were reviewed till June 2015. We noted the incidence of TB, INH tolerability, and development of resistance. We compared the incidence of TB with the historical controls who never received the prophylaxis.

RESULTS

A total of 910 patients were reviewed and followed up for 4.8 years. INH prophylaxis was completed by 825 (91%) patients. A total of 46 patients (5%) developed active TB as compared to 15% in the historical controls. The median time of TB diagnosis from transplantation was 2.8 years. In the first-year post transplant, out of total TB cases, 52% occurred in the historical controls whereas 13% occurred in study cohort. Around 67% had TB >2 years after transplant. Overall 1.43% had hepatotoxicity. There was a significant reduction in TB among those who completed prophylaxis to those who did not (p < 0.001). Of 14 cultures, one isolate was INH resistant (7%).

CONCLUSION

INH prophylaxis was well tolerated. The incidence of TB decreased in the first 2 years. However there was a surge in TB cases 1 year after stopping INH therapy. We should consider prolonging the duration of INH prophylaxis in high TB burden countries in renal transplant recipients.

Effectiveness of isoniazid preventive therapy on incidence of tuberculosis among HIV-infected adults in programme setting

Background & objectives:

As India and other developing countries are scaling up isoniazid preventive therapy (IPT) for people living with HIV (PLHIV) in their national programmes, we studied the feasibility and performance of IPT in terms of treatment adherence, outcome and post-treatment effect when given under programmatic settings.

Methods:

A multicentre, prospective pilot study was initiated among adults living with HIV on isoniazid 300 mg with pyridoxine 50 mg after ruling out active tuberculosis (TB). Symptom review and counselling were done monthly during IPT and for six-month post-IPT. The TB incidence rate was calculated and risk factors were identified.

Results:

Among 4528 adults living with HIV who initiated IPT, 4015 (89%) successfully completed IPT. IPT was terminated in 121 adults (3%) due to grade 2 or above adverse events. Twenty five PLHIVs developed TB while on IPT. The incidence of TB while on IPT was 1.17/100 person-years (p-y) [95% confidence interval (CI) 0.8-1.73] as compared to TB incidence of 2.42/100 p-y (95% CI 1.90-3.10) during the pre-IPT period at these centres (P=0.017). The incidence of TB post-IPT was 0.64/100 p-y (95% CI 0.04-1.12). No single factor was significantly associated with the development of TB.

Interpretation & conclusions:

Under programmatic settings, completion of IPT treatment was high, adverse events minimal with good post-treatment protection. After ruling out TB, IPT should be offered to all PLHIVs, irrespective of their antiretroviral therapy (ART) status. Scaling-up of IPT services including active case finding, periodic counselling on adherence and re-training of ART staff should be prioritized to reduce the TB burden in this community.

HIV-associated tuberculosis

Tuberculosis (TB) remains a leading cause of morbidity and mortality among people living with HIV. HIV-associated TB disproportionally affects African countries, particularly vulnerable groups at risk for both TB and HIV. Currently available TB diagnostics perform poorly in people living with HIV; however, new diagnostics such as Xpert Ultra and lateral flow urine lipoarabinomannan assays can greatly facilitate diagnosis of TB in people living with HIV. TB preventive treatment has been underutilized despite its proven benefits independent of antiretroviral therapy (ART). Shorter regimens using rifapentine can support increased availability and scale-up. Mortality is high in people with HIV-associated TB, and timely initiation of ART is critical. Programs should provide decentralized and integrated TB and HIV care in settings with high burden of both diseases to improve access to services that diagnose TB and HIV as early as possible. The new prevention and diagnosis tools recently recommended by WHO offer an immense opportunity to advance our fight against HIV-associated TB. They should be made widely available and scaled up rapidly supported by adequate funding with robust monitoring of the uptake to advance global TB elimination.

Cost-effectiveness of post-treatment follow-up examinations and secondary prevention of tuberculosis in a high-incidence setting: a model-based analysis

BACKGROUND

In settings of high tuberculosis incidence, previously treated individuals remain at high risk of recurrent tuberculosis and contribute substantially to overall disease burden. Whether tuberculosis case finding and preventive interventions among previously treated people are cost-effective has not been established. We aimed to estimate costs and health benefits of annual post-treatment follow-up examinations and secondary preventive therapy for tuberculosis in a tuberculosis-endemic setting.

METHODS

We developed a transmission-dynamic mathematical model and calibrated it to data from two high-incidence communities of approximately 40 000 people in suburban Cape Town, South Africa. We used the model to estimate overall cost and disability-adjusted life-years (DALYs) associated with annual follow-up examinations and secondary isoniazid preventive therapy (IPT), alone and in combination, among individuals completing tuberculosis treatment. We investigated scenarios under which these interventions were restricted to the first year after treatment completion, or extended indefinitely. For each intervention scenario, we projected health system costs and DALYs averted with respect to the current status quo of tuberculosis control. All estimates represent mean values derived from 1000 epidemic trajectories simulated over a 10-year period (2019-28), with 95% uncertainty intervals (UIs) calculated as the 2·5th and 97·5th percentile values.

FINDINGS

We estimated that a single follow-up examination at the end of the first year after treatment completion combined with 12 months of secondary IPT would avert 2472 DALYs (95% UI -888 to 7801) over a 10-year period and is expected to be cost-saving compared with current control efforts. Sustained annual follow-up and continuous secondary IPT beyond the first year after treatment would avert an additional 1179 DALYs (-1769 to 4377) over 10 years at an expected additional cost of US$18·2 per DALY averted. Strategies of follow-up without secondary IPT were dominated (ie, expected to result in lower health impact at higher costs) by strategies that included secondary IPT.

INTERPRETATION

In this high-incidence setting, post-treatment follow-up and secondary preventive therapy can accelerate declines in tuberculosis incidence and potentially save resources for tuberculosis control. Empirical trials to assess the feasibility of these interventions in settings most severely affected by tuberculosis are needed.

FUNDING

National Institutes of Health, Günther Labes Foundation, Oskar Helene Heim Foundation.

TB preventive therapy for people living with HIV: key considerations for scale-up in resource-limited settings

Tuberculosis (TB) is the leading cause of death for persons living with the human immunodeficiency virus (PLHIV). TB preventive therapy (TPT) works synergistically with, and independently of, antiretroviral therapy to reduce TB morbidity, mortality and incidence among PLHIV. However, although TPT is a crucial and cost-effective component of HIV care for adults and children and has been recommended as an international standard of care for over a decade, it remains highly underutilized. If we are to end the global TB epidemic, we must address the significant reservoir of tuberculous infection, especially in those, such as PLHIV, who are most likely to progress to TB disease. To do so, we must confront the pervasive perception that barriers to TPT scale-up are insurmountable in resource-limited settings. Here we review available evidence to address several commonly stated obstacles to TPT scale-up, including the need for the tuberculin skin test, limited diagnostic capacity to reliably exclude TB disease, concerns about creating drug resistance, suboptimal patient adherence to therapy, inability to monitor for and prevent adverse events, a 'one size fits all' option for TPT regimen and duration, and uncertainty about TPT use in children, adolescents, and pregnant women. We also discuss TPT delivery in the era of differentiated care for PLHIV, how best to tackle advanced planning for drug procurement and supply chain management, and how to create an enabling environment for TPT scale-up success.

Projected population-wide impact of antiretroviral therapy-linked isoniazid preventive therapy in a high-burden setting

OBJECTIVE

Both isoniazid preventive therapy (IPT) and antiretroviral therapy (ART) reduce tuberculosis risk in individuals living with HIV. We sought to estimate the broader, population-wide impact of providing a pragmatically implemented 12-month IPT regimen to ART recipients in a high-burden community.

DESIGN

Dynamic transmission model of a tuberculosis (TB)-HIV epidemic, calibrated to site-specific, historical epidemiologic and clinical trial data from Khayelitsha, South Africa.

METHODS

We projected the 5-year impact of delivering a 12-month IPT regimen community-wide to 85% of new ART initiators and 15%/year of those already on ART, accounting for IPT-attributable reductions in TB infection, progression, and transmission. We also evaluated scenarios of continuously-delivered IPT, ongoing ART scale-up, and lower tuberculosis incidence.

RESULTS

Under historical (early 2010) ART coverage, this ART-linked IPT intervention prevented one tuberculosis case per 18 [95% credible interval (CrI) 11-29] people treated. It lowered TB incidence by a projected 23% (95% CrI 14-30%) among people receiving ART, and by 5.2% (95% CrI 2.9-8.7%) in the total population. Continuous IPT reduced the number needed to treat to prevent one case of TB to 10 (95% CrI 7-16), though it required 74% more person-years of therapy (95% CrI 64-94%) to prevent one TB case, relative to 12-month therapy. Under expanding ART coverage, the tuberculosis incidence reduction achieved by 12-month IPT grew to 7.6% (95% CrI 4.3-12.6%). Effect sizes were similar in a simulated setting of lower TB incidence.

CONCLUSIONS

IPT in conjunction with ART reduces tuberculosis incidence among those who receive therapy and has additional impact on tuberculosis transmission in the population.

Tuberculosis control interventions targeted to previously treated people in a high-incidence setting: a modelling study

BACKGROUND

In high-incidence settings, recurrent disease among previously treated individuals contributes substantially to the burden of incident and prevalent tuberculosis. The extent to which interventions targeted to this high-risk group can improve tuberculosis control has not been established. We aimed to project the population-level effect of control interventions targeted to individuals with a history of previous tuberculosis treatment in a high-incidence setting.

METHODS

We developed a transmission-dynamic model of tuberculosis and HIV in a high-incidence setting with a population of roughly 40 000 people in suburban Cape Town, South Africa. The model was calibrated to data describing local demography, TB and HIV prevalence, TB case notifications and treatment outcomes using a Bayesian calibration approach. We projected the effect of annual targeted active case finding in all individuals who had previously completed tuberculosis treatment and targeted active case finding combined with lifelong secondary isoniazid preventive therapy. We estimated the effect of these targeted interventions on local tuberculosis incidence, prevalence, and mortality over a 10 year period (2016-25).

FINDINGS

We projected that, under current control efforts in this setting, the tuberculosis epidemic will remain in slow decline for at least the next decade. Additional interventions targeted to previously treated people could greatly accelerate these declines. We projected that annual targeted active case finding combined with secondary isoniazid preventive therapy in those who previously completed tuberculosis treatment would avert 40% (95% uncertainty interval [UI] 21-56) of incident tuberculosis cases and 41% (16-55) of tuberculosis deaths occurring between 2016 and 2025.

INTERPRETATION

In this high-incidence setting, the use of targeted active case finding in combination with secondary isoniazid preventive therapy in previously treated individuals could accelerate decreases in tuberculosis morbidity and mortality. Studies to measure cost and resource implications are needed to establish the feasibility of this type of targeted approach for improving tuberculosis control in settings with high tuberculosis and HIV prevalence.

FUNDING

National Institutes of Health, German Research Foundation.