Modeling of novel diagnostic strategies for active tuberculosis - a systematic review: current practices and recommendations

Strengthening health systems to improve the value of tuberculosis diagnostics in South Africa: A cost and cost-effectiveness analysis

BACKGROUND

In South Africa, replacing smear microscopy with Xpert-MTB/RIF (Xpert) for tuberculosis diagnosis did not reduce mortality and was cost-neutral. The unchanged mortality has been attributed to suboptimal Xpert implementation. We developed a mathematical model to explore how complementary investments may improve cost-effectiveness of the tuberculosis diagnostic algorithm.

METHODS

Complementary investments in the tuberculosis diagnostic pathway were compared to the status quo. Investment scenarios following an initial Xpert test included actions to reduce pre-treatment loss-to-follow-up; supporting same-day clinical diagnosis of tuberculosis after a negative result; and improving access to further tuberculosis diagnostic tests following a negative result. We estimated costs, deaths and disability-adjusted-life-years (DALYs) averted from provider and societal perspectives. Sensitivity analyses explored the mediating influence of behavioural, disease- and organisational characteristics on investment effectiveness.

FINDINGS

Among a cohort of symptomatic patients tested for tuberculosis, with an estimated active tuberculosis prevalence of 13%, reducing pre-treatment loss-to-follow-up from ~20% to ~0% led to a 4% (uncertainty interval [UI] 3; 4%) reduction in mortality compared to the Xpert scenario. Improving access to further tuberculosis diagnostic tests from ~4% to 90% among those with an initial negative Xpert result reduced overall mortality by 28% (UI 27; 28) at $39.70/ DALY averted. Effectiveness of investment scenarios to improve access to further diagnostic tests was dependent on a high return rate for follow-up visits.

INTERPRETATION

Investing in direct and indirect costs to support the TB diagnostic pathway is potentially highly cost-effective.

Predicting the impact of patient and private provider behavior on diagnostic delay for pulmonary tuberculosis patients in India: A simulation modeling study

BACKGROUND

Tuberculosis (TB) incidence in India continues to be high due, in large part, to long delays experienced by patients before successful diagnosis and treatment initiation, especially in the private sector. This diagnostic delay is driven by patients' inclination to switch between different types of providers and providers' inclination to delay ordering of accurate diagnostic tests relevant to TB. Our objective is to quantify the impact of changes in these behavioral characteristics of providers and patients on diagnostic delay experienced by pulmonary TB patients.

METHODS AND FINDINGS

We developed a discrete event simulation model of patients' diagnostic pathways that captures key behavioral characteristics of providers (time to order a test) and patients (time to switch to another provider). We used an expectation-maximization algorithm to estimate the parameters underlying these behavioral characteristics, with quantitative data encoded from detailed interviews of 76 and 64 pulmonary TB patients in the 2 Indian cities of Mumbai and Patna, respectively, which were conducted between April and August 2014. We employed the estimated model to simulate different counterfactual scenarios of diagnostic pathways under altered behavioral characteristics of providers and patients to predict their potential impact on the diagnostic delay. Private healthcare providers including chemists were the first point of contact for the majority of TB patients in Mumbai (70%) and Patna (94%). In Mumbai, 45% of TB patients first approached less-than-fully-qualified providers (LTFQs), who take 28.71 days on average for diagnosis. About 61% of these patients switched to other providers without a diagnosis. Our model estimates that immediate testing for TB by LTFQs at the first visit (at the current level of diagnostic accuracy) could reduce the average diagnostic delay from 35.53 days (95% CI: 34.60, 36.46) to 18.72 days (95% CI: 18.01, 19.43). In Patna, 61% of TB patients first approached fully qualified providers (FQs), who take 9.74 days on average for diagnosis. Similarly, immediate testing by FQs at the first visit (at the current level of diagnostic accuracy) could reduce the average diagnostic delay from 23.39 days (95% CI: 22.77, 24.02) to 11.16 days (95% CI: 10.52, 11.81). Improving the diagnostic accuracy of providers per se, without reducing the time to testing, was not predicted to lead to any reduction in diagnostic delay. Our study was limited because of its restricted geographic scope, small sample size, and possible recall bias, which are typically associated with studies of patient pathways using patient interviews.

CONCLUSIONS

In this study, we found that encouraging private providers to order definitive TB diagnostic tests earlier during patient consultation may have substantial impact on reducing diagnostic delay in these urban Indian settings. These results should be combined with disease transmission models to predict the impact of changes in provider behavior on TB incidence.

Disparities in model-based cost-effectiveness analyses of tuberculosis diagnosis: A systematic review

Background

Structural approach disparities were minimally addressed in past systematic reviews of model-based cost-effectiveness analyses addressing Tuberculosis management strategies. This review aimed to identify the structural approach disparities in model-based cost-effectiveness analysis studies addressing Tuberculosis diagnosis and describe potential hazards caused by those disparities.

Methods

A systematic search to identify studies published before October 2015 was performed in five electronic databases. After removal of duplication, studies’ titles and abstracts were screened based on predetermined criteria. The full texts of potentially relevant studies were subsequently screened and excluded when they did not address active pulmonary Tuberculosis diagnosis. Quality of the studies was assessed using the “Philips’ checklist.” Various data regarding general information, cost-effectiveness results, and disease modeling were extracted using standardized data extraction forms. Data pertaining to models’ structural approaches were compared and analyzed qualitatively for their applicability in various study settings, as well as their potential influence on main outcomes and cost-effectiveness conclusion.

Results

A total of 27 studies were included in the review. Most studies utilized a static model, which could underestimate the cost-effectiveness of the diagnostic tools strategies, due to the omission of indirect diagnosis effects, i.e. transmission reduction. A few structural assumption disparities were found in the dynamic models. Extensive disparities were found in the static models, consisting of varying structural assumptions regarding treatment outcomes, clinical diagnosis and empirical treatment, inpatient discharge decision, and re-diagnosis of false negative patients.

Conclusion

In cost-effectiveness analysis studies addressing active pulmonary Tuberculosis diagnosis, models showed numerous disparities in their structural approaches. Several structural approaches could be inapplicable in certain settings. Furthermore, they could contribute to under- or overestimation of the cost-effectiveness of the diagnosis tools or strategies. They could thus lead to ambiguities and difficulties when interpreting a study result. A set of recommendations is proposed to manage issues related to these structural disparities.

Performance of a Highly Sensitive Mycobacterium tuberculosis Complex Real-Time PCR Assay for Diagnosis of Pulmonary Tuberculosis in a Low-Prevalence Setting: a Prospective Intervention Study

The potential impact of routine real-time PCR testing of respiratory specimens from patients with presumptive tuberculosis in terms of diagnostic accuracy and time to tuberculosis treatment inception in low-prevalence settings remains largely unexplored. We conducted a prospective intervention cohort study. Respiratory specimens from 1,020 patients were examined by acid-fast bacillus smear microscopy, tested by a real-time Mycobacterium tuberculosis complex PCR assay (Abbott RealTime MTB PCR), and cultured in mycobacterial media. Seventeen patients tested positive by PCR (5 were acid-fast bacillus smear positive and 12 acid-fast bacillus smear negative), and Mycobacterium tuberculosis was recovered from cultures for 12 of them. Patients testing positive by PCR and negative by culture (n = 5) were treated and deemed to have responded to antituberculosis therapy. There were no PCR-negative/culture-positive cases, and none of the patients testing positive for nontuberculous mycobacteria (n = 20) yielded a positive PCR result. The data indicated that routine testing of respiratory specimens from patients with presumptive tuberculosis by the RealTime MTB PCR assay improves the tuberculosis diagnostic yield and may reduce the time to antituberculosis treatment initiation. On the basis of our data, we propose a novel mycobacterial laboratory algorithm for tuberculosis diagnosis.

Screening for latent and active tuberculosis infection in the elderly at admission to residential care homes: A cost-effectiveness analysis in an intermediate disease burden area

BACKGROUND

Tuberculosis (TB) in the elderly remains a challenge in intermediate disease burden areas like Hong Kong. Given a higher TB burden in the elderly and limited impact of current case-finding strategy by patient-initiated pathway, proactive screening approaches for the high-risk group could be optimal and increasingly need targeted economic evaluations. In this study, we examined whether and under what circumstance the screening strategies are cost-effective compared with no screening strategy for the elderly at admission to residential care homes.

METHODS

A decision analytic process based on Markov model was adopted to evaluate the cost-effectiveness of four strategies: (i) no screening, (ii) TB screening (CXR) and (iii) TB screening (Xpert) represent screening for TB in symptomatic elderly by chest X-ray and Xpert® MTB/RIF respectively, and (iv) LTBI/TB screening represents screening for latent and active TB infection by QuantiFERON®-TB Gold In-Tube and chest X-ray. The target population was a hypothetical cohort of 65-year-old people, using a health service provider perspective and a time horizon of 20 years. The outcomes were direct medical costs, life-years and quality-adjusted life-years (QALYs) measured by incremental cost-effectiveness ratio (ICER).

RESULTS

In the base-case analysis, no screening was the most cost-saving; TB screening (CXR) was dominated by TB screening (Xpert); LTBI/TB screening resulted in more life-years and QALYs accrued. The ICERs of LTBI/TB screening were US$19,712 and US$29,951 per QALY gained compared with no screening and TB screening (Xpert), respectively. At the willingness-to-pay threshold of US$50,000 per QALY gained, LTBI/TB screening was the most cost-effective when the probability of annual LTBI reactivation was greater than 0.155% and acceptability of LTBI/TB screening was greater than 38%. In 1,000 iterations of Monte Carlo simulation, the probabilities of no screening, TB screening (CXR), TB screening (Xpert), and LTBI/TB screening to be cost-effective were 0, 1.3%, 20.1%, and 78.6% respectively.

CONCLUSIONS

Screening for latent and active TB infection in Hong Kong elderly people at admission to residential care homes appears to be highly effective and cost-effective. The key findings may be the next key factor to bring down TB endemic in the elderly population among intermediate TB burden areas.

Diagnostics of tuberculosis and differentiation of nonspecific tuberculin reactions in animals

Tuberculosis is a serious disease of humans and animals, caused by bacteria of the Mycobacterium genus. This leads to complications in the life of the sick person, and subsequently to death. The cattle, who have been diagnosed with this bacterium, are usually sent to the slaughter, with the result that their livestock is reduced. Mycobacteriosis is also a disease, after determining which cattle are most often sent to slaughter. Such a reduction in livestock numbers has a negative effect on the economy. Of the 300 samples from the animals, 25 cultures of atypical bacteria responding to tuberculin were isolated. A series of tests – intravenous tuberculin test, ophthalmic test, palpebral test, “ZhAT” test, showed that most of the tuberculosis changes in cattle were found in regional lymph nodes more often than in internal organs. In healthy for tuberculosis cows, at the age of 4–9 years, seasonal nonspecific sensitivity to tuberculin is observed. Implementation of the developed express method of glutaraldehyde test on farms in healthy tuberculosis will speed up the diagnosis of tuberculosis and mycobacteriosis in animals that reacted to tuberculin and will exclude short-term nonspecific sensitization of their organism to tuberculin. The introduction of this methodology can be used to diagnose and clearly differentiate the diagnoses of “tuberculosis” and “mycobacteriosis” in cattle. This will cure part of the livestock and reduce the amount of slaughter.

The strategic framework of tuberculosis control and prevention in the elderly: a scoping review towards End TB targets

With the rapid pace of population ageing, tuberculosis (TB) in the elderly increasingly becomes a public health challenge. Despite the increasing burden and high risks for TB in the elderly, targeted strategy has not been well understood and evaluated. We undertook a scoping review to identify current TB strategies, research and policy gaps in the elderly and summarized the results within a strategic framework towards End TB targets. Databases of Embase, MEDLINE, Global health and EBM reviews were searched for original studies, review articles, and policy papers published in English between January 1990 and December 2015. Articles examining TB strategy, program, guideline or intervention in the elderly from public health perspective were included.Nineteen articles met the inclusion criteria. Most of them were qualitative studies, issued in high- and middle-income countries and after 2000. To break the chain of TB transmission and reactivation in the elderly, infection control, interventions of avoiding delay in diagnosis and containment are essential for preventing transmission, especially in elderly institutions and aged immigrants; screening of latent TB infection and preventive therapy had effective impacts on reducing the risk of reactivation and should be used less reluctantly in older people; optimizing early case-finding with a high index of suspicion, systematic screening for prioritized high-risk groups, initial empirical and adequate follow-up treatment with close monitoring and evaluation, as well as enhanced programmatic management are fundamental pillars for active TB elimination. Evaluation of TB epidemiology, risk factors, impacts and cost-effectiveness of interventions, adopting accurate and rapid diagnostic tools, shorter and less toxic preventive therapy, are critical issues for developing strategy in the elderly towards End TB targets.TB control strategies in the elderly were comprehensively mapped in a causal link pathway. The framework and principals identified in this study will help to evaluate and improve current program, develop targeted strategy, as well as raise more discussions on the research priority settings and policy transitions. Given the scarceness of policy and evaluated interventions, as well as the unawareness of shifting TB epidemiology and strategy especially in developing countries, the increasing need of a ready TB program for the elderly warrants further research.

Molecular diagnosis of central nervous system opportunistic infections and mortality in HIV-infected adults in Central China

BACKGROUND

CSF PCR is the standard diagnostic technique used in resource-rich settings to detect pathogens of the CNS infection. However, it is not currently used for routine CSF testing in China. Knowledge of CNS opportunistic infections among people living with HIV in China is limited.

METHODS

Intensive cerebrospiral fluid (CSF) testing was performed to evaluate for bacterial, viral and fungal etiologies. Pathogen-specific primers were used to detect DNA from cytomegalovirus (CMV), herpes simplex virus (HSV), varicella-zoster virus (VZV), Epstein-Barr virus (EBV), human herpesvirus 6 (HHV-6) and John Cunningham virus (JCV) via real-time polymerase chain reaction (PCR).

RESULTS

Cryptococcal meningitis accounted for 63.0% (34 of 54) of all causes of meningitis, 13.0% (7/54) for TB, 9.3% (5/54) for Toxoplasma gondii. Of 54 samples sent for viral PCR, 31.5% (17/54) were positive, 12 (22.2%) for CMV, 2 (3.7%) for VZV, 1 (1.9%) for EBV, 1 (1.9%) for HHV-6 and 1 (1.9%) for JCV. No patient was positive for HSV. Pathogen-based treatment and high GCS score tended to have a lower mortality rate, whereas patients with multiple pathogens infection, seizures or intracranial hypertension showed higher odds of death.

CONCLUSION

CNS OIs are frequent and multiple pathogens often coexist in CSF. Cryptococcal meningitis is the most prevalent CNS disorders among AIDS. The utility of molecular diagnostics for pathogen identification combined with the knowledge provided by the investigation may improve the diagnosis of AIDS related OIs in resource-limited developing countries, but the cost-efficacy remains to be further evaluated.

Migration to middle-income countries and tuberculosis-global policies for global economies

Background

International migration to middle-income countries is increasing and its health consequences, in particular increasing transmission rates of tuberculosis (TB), deserve consideration. Migration and TB are a matter of concern in high-income countries and targeted screening of migrants for active and latent TB infection is a main strategy to manage risk and minimize transmission. In this paper, we discuss some aspects of TB control and migration in the context of middle-income countries, together with the prospect of responding with equitable and comprehensive policies.

Main body

TB rates in middle-income countries remain disproportionally high among the poorest and most vulnerable groups in large cities where most migrant populations are concentrated. Policies that tackle migrant TB in high-income countries may be inadequate for middle-income countries because of their different socio-economic and cultural scenarios. Strategies to control TB in these settings must take into account the characteristics of middle-income countries and the complexity of TB as a disease of poverty. Intersectoral policies of social protection such as cash-transfer programs help reducing poverty and improving health in vulnerable populations. We address the development of new approaches to improve well-established strategies including contact tracing and active and latent TB screening as an ‘add on’ to the existing health care guidelines of conditional cash transfer programs. In addition, we discuss how it might improve health and welfare among both poor migrants and locally-born populations. Authorities from middle-income countries should recognise that migrants are a vulnerable social group and promote cooperation efforts between sending and receiving countries for mitigation of poverty and prevention of disease in this group.

Conclusions

Middle-income countries have long sent migrants overseas. However, the influx of large migrant populations into their societies is relatively new and a growing phenomenon and it is time to set comprehensive goals to improve health among these communities. Conditional cash transfer policies with TB screening and strengthening of DOTS are some strategies that deserve attention. Reduction of social and health inequality among migrants should be incorporated into concerted actions to meet TB control targets.

Clinical Impact and Cost-effectiveness of Xpert MTB/RIF Testing in Hospitalized Patients With Presumptive Pulmonary Tuberculosis in the United States

Background

Microscopic examination of acid-fast-stained sputum smears is the current standard of care in the United States to determine airborne infection isolation (AII) of inpatients with presumptive pulmonary tuberculosis (PTB). However, nucleic acid amplification testing (NAAT) with the Xpert MTB/RIF assay (Xpert) may be more efficient and less costly.

Methods

This prospective observational cohort study enrolled a consecutive sample of 318 AII-eligible inpatients from a public hospital in Seattle, Washington, from March 2012 to October 2013. Sputum samples were collected from each inpatient and analyzed using smear microscopy, culture, drug susceptibility testing, and NAAT. The performance, clinical utility (AII duration and survival), and cost-effectiveness from an institutional perspective were compared for 5 testing strategies.

Results

Among the 318 admissions with presumptive PTB, 20 (6.3%) were culture-positive for Mycobacterium tuberculosis. The sensitivity of 1 Xpert, 2 Xperts, 2 smears, or 3 smears compared to culture was 0.85 (95% confidence interval [CI], .61–.96), 0.95 (95% CI, .73–1.0), 0.70 (95% CI, .46–.88), and 0.80 (95% CI, .56–.93), respectively. A cost-effectiveness analysis of the study results demonstrated that an Xpert test on 1 unconcentrated sputum sample (assuming equivalent results for unconcentrated and concentrated sputum samples) is the most cost-effective strategy (99.9% preferred at willingness-to-pay of US$50000) and on average would save 51.5 patient-hours in AII and up to $11466 relative to microscopy without a compromise in sensitivity.

Conclusions

In hospitalized patients with presumptive PTB in a low-burden setting, NAAT can reduce AII and is comparably sensitive, more specific, and more cost-effective than smear microscopy.

The Point-of-Care Laboratory in Clinical Microbiology

Point-of-care (POC) laboratories that deliver rapid diagnoses of infectious diseases were invented to balance the centralization of core laboratories. POC laboratories operate 24 h a day and 7 days a week to provide diagnoses within 2 h, largely based on immunochromatography and real-time PCR tests. In our experience, these tests are conveniently combined into syndrome-based kits that facilitate sampling, including self-sampling and test operations, as POC laboratories can be operated by trained operators who are not necessarily biologists. POC laboratories are a way of easily providing clinical microbiology testing for populations distant from laboratories in developing and developed countries and on ships. Modern Internet connections enable support from core laboratories. The cost-effectiveness of POC laboratories has been established for the rapid diagnosis of tuberculosis and sexually transmitted infections in both developed and developing countries.

Feasibility of achieving the 2025 WHO global tuberculosis targets in South Africa, China, and India: a combined analysis of 11 mathematical models

Background

The post-2015 End TB Strategy proposes targets of 50% reduction in tuberculosis incidence and 75% reduction in mortality from tuberculosis by 2025. We aimed to assess whether these targets are feasible in three high-burden countries with contrasting epidemiology and previous programmatic achievements.

Methods

11 independently developed mathematical models of tuberculosis transmission projected the epidemiological impact of currently available tuberculosis interventions for prevention, diagnosis, and treatment in China, India, and South Africa. Models were calibrated with data on tuberculosis incidence and mortality in 2012. Representatives from national tuberculosis programmes and the advocacy community provided distinct country-specific intervention scenarios, which included screening for symptoms, active case finding, and preventive therapy.

Findings

Aggressive scale-up of any single intervention scenario could not achieve the post-2015 End TB Strategy targets in any country. However, the models projected that, in the South Africa national tuberculosis programme scenario, a combination of continuous isoniazid preventive therapy for individuals on antiretroviral therapy, expanded facility-based screening for symptoms of tuberculosis at health centres, and improved tuberculosis care could achieve a 55% reduction in incidence (range 31–62%) and a 72% reduction in mortality (range 64–82%) compared with 2015 levels. For India, and particularly for China, full scale-up of all interventions in tuberculosis-programme performance fell short of the 2025 targets, despite preventing a cumulative 3·4 million cases. The advocacy scenarios illustrated the high impact of detecting and treating latent tuberculosis.

Interpretation

Major reductions in tuberculosis burden seem possible with current interventions. However, additional interventions, adapted to country-specific tuberculosis epidemiology and health systems, are needed to reach the post-2015 End TB Strategy targets at country level.

Funding

Bill and Melinda Gates Foundation

Enhancement of PCR Detection Limit by Single-Tube Restriction Endonuclease-PCR (RE-PCR)

BACKGROUND

Polymerase chain reaction (PCR) is widely used in biological research and diagnostics because of its high sensitivity and specificity. However, the sensitivity of PCR is strongly influenced by topological characteristics of the template. Supercoiled templates are known to inhibit PCR, whereas linearized forms of the same supercoiled templates facilitate PCR.

OBJECTIVES

This study was conducted to compare the PCR efficiency of circular supercoiled DNA templates to their restriction endonuclease (RE)-mediated linearized forms. Additionally, we also evaluated the possibility of RE digestion of the circular supercoiled templates within the complete PCR buffer.

METHODS

Following a systematic approach, we demonstrated that circular supercoiled templates could be efficiently linearized by RE in the complete PCR buffer itself. This allowed linearization of circular supercoiled templates and their subsequent amplification in the PCR buffer in a single-tube format.

RESULTS

Using this extremely simple RE-PCR approach, we documented up to tenfold increases in detection efficiency of PCR with two different circular supercoiled templates of clinical origin, including an international calibration standard.

CONCLUSIONS

This inexpensive and easy approach to increasing PCR sensitivity can be easily adapted to any standard PCR protocol aimed at amplifying circular supercoiled genomes. Apart from its application in the development of sensitive clinical diagnostic PCR assays for a large number of organisms, this method could also prove to be very useful in simplifying the existing protocols for other applications where pre-PCR restriction digestion is required, such as mutation detection, genotyping, and selective template amplification.

Incorporating Demand and Supply Constraints into Economic Evaluations in Low-Income and Middle-Income Countries

Global guidelines for new technologies are based on cost and efficacy data from a limited number of trial locations. Country-level decision makers need to consider whether cost-effectiveness analysis used to inform global guidelines are sufficient for their situation or whether to use models that adjust cost-effectiveness results taking into account setting-specific epidemiological and cost heterogeneity. However, demand and supply constraints will also impact cost-effectiveness by influencing the standard of care and the use and implementation of any new technology. These constraints may also vary substantially by setting. We present two case studies of economic evaluations of the introduction of new diagnostics for malaria and tuberculosis control. These case studies are used to analyse how the scope of economic evaluations of each technology expanded to account for and then address demand and supply constraints over time. We use these case studies to inform a conceptual framework that can be used to explore the characteristics of intervention complexity and the influence of demand and supply constraints. Finally, we describe a number of feasible steps that researchers who wish to apply our framework in cost-effectiveness analyses.

Bridging the gap between evidence and policy for infectious diseases: How models can aid public health decision-making

The dominant approach to decision-making in public health policy for infectious diseases relies heavily on expert opinion, which often applies empirical evidence to policy questions in a manner that is neither systematic nor transparent. Although systematic reviews are frequently commissioned to inform specific components of policy (such as efficacy), the same process is rarely applied to the full decision-making process. Mathematical models provide a mechanism through which empirical evidence can be methodically and transparently integrated to address such questions. However, such models are often considered difficult to interpret. In addition, models provide estimates that need to be iteratively reevaluated as new data or considerations arise. Using the case study of a novel diagnostic for tuberculosis, a framework for improved collaboration between public health decision-makers and mathematical modellers that could lead to more transparent and evidence-driven policy decisions for infectious diseases in the future is proposed. The framework proposes that policymakers should establish long-term collaborations with modellers to address key questions, and that modellers should strive to provide clear explanations of the uncertainty of model structure and outputs. Doing so will improve the applicability of models and clarify their limitations when used to inform real-world public health policy decisions.

First and second line drug resistance among treatment naïve pulmonary tuberculosis patients in a district under Revised National Tuberculosis Control Programme (RNTCP) in New Delhi

There is limited information of level of drug resistance to first-line and second line anti-tuberculosis agents in treatment naïve pulmonary tuberculosis (PTB) patients from the Indian region. Therefore, the present prospective study was conducted to determine the antimicrobial susceptibility to first-line and second line anti-TB drug resistance in such patients. Sputum samples from consecutive treatment naïve PTB cases registered in Lala Ram Sarup (LRS) district, under RNTCP containing 12 Directly Observed Treatment Centre’s (DOTS), were enrolled using cluster sampling technology. A total of 453 samples were received from July 2011 to June 2012. All samples were cultured on solid medium followed by drug susceptibility to first and second line anti-tubercular drugs as per RNTCP guidelines. Primary multi-drug resistance (MDR) was found to be 18/453; (4.0%). Extensively drug resistance (XDR) was found in one strain (0.2%), which was found to be resistant to other antibiotics. Data of drug resistant tuberculosis among treatment naïve TB patients are lacking in India. The presence of XDR-TB and high MDR-TB in small population studied, calls for conducting systematic multi-centric surveillance across the country.

Tuberculosis control strategies to reach the 2035 global targets in China: the role of changing demographics and reactivation disease

BACKGROUND

In the last 20 years, China ramped up a DOTS (directly observed treatment, short-course)-based tuberculosis (TB) control program with 80% population coverage, achieving the 2015 Millennium Development Goal of a 50% reduction in TB prevalence and mortality. Recently, the World Health Organization developed the End TB Strategy, with an overall goal of a 90% reduction in TB incidence and a 95% reduction in TB deaths from 2015-2035. As the TB burden shifts to older individuals and China's overall population ages, it is unclear if maintaining the current DOTS strategy will be sufficient for China to reach the global targets.

METHODS

We developed an individual-based computational model of TB transmission, implementing realistic age demographics and fitting to country-level data of age-dependent prevalence over time. We explored the trajectory of TB burden if the DOTS strategy is maintained or if new interventions are introduced using currently available and soon-to-be-available tools. These interventions include increasing population coverage of DOTS, reducing time to treatment, increasing treatment success, and active case finding among elders > 65 years old. We also considered preventative therapy in latently infected elders, a strategy limited by resource constraints and the risk of adverse events.

RESULTS

Maintenance of the DOTS strategy reduces TB incidence and mortality by 42% (95% credible interval, 27-59%) and 41% (5-64%), respectively, between 2015 and 2035. A combination of all feasible interventions nears the 2035 mortality target, reducing TB incidence and mortality by 59% (50-76%) and 83% (73-94%). Addition of preventative therapy for elders would enable China to nearly reach both the incidence and mortality targets, reducing incidence and mortality by 84% (78-93%) and 92% (86-98%).

CONCLUSIONS

The current decline in incidence is driven by two factors: maintaining a low level of new infections in young individuals and the aging out of older latently infected individuals who contribute incidence due to reactivation disease. While further reducing the level of new infections has a modest effect on burden, interventions that limit reactivation have a greater impact on TB burden. Tools that make preventative therapy more feasible on a large scale and in elders will help China achieve the global targets.