Pre-treatment loss to follow-up in tuberculosis patients in low- and lower-middle-income countries and high-burden countries: a systematic review and meta-analysis

Catastrophic care-seeking costs as an indicator for lung health

Costs incurred during care-seeking for chronic respiratory disease are a major problem with severe consequences for socio-economic status and health outcomes. Most of the published evidence to date relates to tuberculosis (TB) and there is a lack of information for the major non-communicable chronic respiratory diseases: asthma and chronic obstructive pulmonary disease (COPD). International policy is recognising the need to address this problem and measure progress towards eliminating catastrophic care-seeking costs (see the post-2015 TB strategy). Current tools for measuring, defining, and understanding the full consequences of catastrophic care-seeking costs are inadequate. We propose two areas of work which are urgently needed to prepare health systems and countries for the burden of chronic lung disease that will fall on poor populations in the coming 10-20 years: a) Rapid scale up of the number and scope of studies of patient costs associated with chronic non-communicable respiratory disease. b) Work towards deeper understanding and effective measurement of catastrophic care-seeking costs. This will produce a range of indicators, such as dissaving, which can more effectively inform health policy decision-making for lung health. These will also be useful for other health problems. We argue that reduction in care-seeking costs will be a key monitoring indicator for improvements in lung health in particular, and health in general, in the coming 10 to 20 years.

Advances in Diagnostic Assays for Tuberculosis

Approximately one-third of the global burden of tuberculosis (TB) remains undiagnosed each year and the vast majority of cases of multidrug-resistant TB remain undetected. Many countries still place heavy reliance on outdated technologies that are blunt and ineffective tools for controlling this epidemic. However, during the past 10 years, there has been substantial progress within the TB diagnostics developmental pipeline. Old technologies have been reviewed and improved and new technologies have been developed and evaluated and are now being implemented. This review summarizes these developments and describes the currently available diagnostic tools. Consideration is given to the requirements of future diagnostic tests and how these should be evaluated not only with regard to their diagnostic accuracy and operational feasibility, but ultimately in terms of whether they impact clinical outcomes cost effectively, especially for those most in need.

A Systematic Review of Studies Evaluating the Cost Utility of Screening High-Risk Populations for Latent Tuberculosis Infection

BACKGROUND

As tuberculosis screening trends to targeting high-risk populations, knowing the cost effectiveness of such screening is vital to decision makers.

OBJECTIVES

The purpose of this review was to compile cost-utility analyses evaluating latent tuberculosis infection (LTBI) screening in high-risk populations that used quality-adjusted life-years (QALYs) as their measure of effectiveness.

DATA SOURCES

A literature search of MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, Web of Knowledge, and PubMed was performed from database start to November 2014.

INCLUSION CRITERIA

Studies performed in populations at high risk of LTBI and subsequent reactivation that used the QALY as an effectiveness measure were included.

STUDY APPRAISAL AND SYNTHESIS

Quality was assessed using the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) checklist. Data extracted included tuberculin skin test (TST) and/or interferon-gamma release assay (IGRA) use, economic, screening, treatment, health state, and epidemiologic parameters. Data were summarized in regard to consistency in model parameters and the incremental cost-effectiveness ratio (ICER), with costs adjusted to 2013 US dollars.

RESULTS

Of 415 studies identified, ultimately eight studies were included in the review. Most took a societal perspective (n = 4), used lifetime time horizons (n = 6), and used Markov models (n = 8). Screening of adult immigrants was found to be cost effective with a TST in one study, but moderately cost effective with an IGRA in another study; screening immigrants arriving more than 5 years prior with an IGRA was moderately cost effective until 44 years of age (n = 1). Screening HIV-positive patients was highly cost effective with a TST (n = 1) and moderately cost effective with an IGRA (n = 1). Screening in those with renal diseases (n = 2) and diabetes (n = 1) was not cost effective.

LIMITATIONS

Very few studies used the QALY as their effectiveness measure. Parameter and study design inconsistencies limit the comparability of studies.

CONCLUSIONS

With validity issues in terms of parameters and assumptions, any conclusion should be interpreted with caution. Despite this, some cautionary recommendations emerged: screening HIV patients with a TST is highly cost effective, while screening adult immigrants with an IGRA is moderately cost effective.

The Multi-Drug Resistant Tuberculosis Diagnosis and Treatment Cascade in Bangladesh

Objectives

To determine, in areas supported by BRAC, Bangladesh i) the pre-diagnosis and pre-treatment attrition among presumptive and confirmed Multi-Drug Resistant Tuberculosis (MDR-TB) patients and ii) factors associated with attrition.

Methods

This was a retrospective cohort study involving record review. Presumptive MDR-TB patients from peripheral microscopy centres serving 60% of the total population of Bangladesh were included in the study. Attrition and turnaround time for MDR-TB diagnosis by Xpert MTB/RIF and treatment initiation were calculated between July 2012 and June 2014.

Results

Of 836 presumptive MDR-TB patients referred from 398 peripheral microscopy centres, 161 MDR-TB patients were diagnosed. The number of diagnosed MDR-TB patients was less than country estimates of MDR-TB patients (2000 cases) during the study period. Among those referred, pre-diagnosis and pre-treatment attrition was 17% and 21% respectively. Median turnaround time for MDR-TB testing, result receipt and treatment initiation was four, zero and five days respectively. Farmers (RR=2.3, p=0.01) and daily wage laborers (RR=2.1, p=0.04) had twice the risk of having pre-diagnosis attrition. Poor record-keeping and unreliable upkeep of presumptive MDR-TB patient databases were identified as challenges at the peripheral microscopy centres.

Conclusion

There was a low proportion of pre-diagnosis and pre-treatment attrition in patients with presumptive and confirmed MDR-TB under programmatic conditions. However, the recording and reporting system did not detect all presumptive MDR-TB patients, highlighting the need to improve the system in order to prevent morbidity, mortality and transmission of MDR-TB in the community.

Costs and Consequences of Using Interferon-γ Release Assays for the Diagnosis of Active Tuberculosis in India

Background

There is growing concern that interferon-γ release assays (IGRAs) are being used off-label for the diagnosis of active tuberculosis (TB) disease in many high-burden settings, including India, where the background prevalence of latent TB infection is high. We analyzed the costs and consequences of using IGRAs for the diagnosis of active TB in India from the perspective of the Indian TB control sector.

Methods and Findings

We constructed a decision analytic model to estimate the incremental cost and effectiveness of IGRAs for the diagnosis of active TB in India. We compared a reference scenario of clinical examination and non-microbiological tests against scenarios in which clinical diagnosis was augmented by the addition of either sputum smear microscopy, IGRA, or Xpert MTB/RIF. We examined costs (in 2013 US dollars) and consequences from the perspective of the Indian healthcare sector. Relative to sputum smear microscopy, use of IGRA for active TB resulted in 23,700 (95% uncertainty range, UR: 3,800 – 38,300) additional true-positive diagnoses, but at the expense of 315,700 (95% UR: 118,300 – 388,400) additional false-positive diagnoses and an incremental cost of US$49.3 million (95% UR: $34.9 – $58.0 million) (2.9 billion Indian Rupees). Relative to Xpert MTB/RIF (including the cost of treatment for drug resistant TB), use of IGRA led to 400 additional TB cases treated (95% UR: [-8,000] – 16,200), 370,600 (95% UR: 252,200 – 441,700) more false-positive diagnoses, 70,400 (95% UR: [-7,900] – 247,200) fewer disability-adjusted life years averted, and US$14.6 million (95%UR: [-$7.2] – $28.7 million) (854 million Indian Rupees) in additional costs.

Conclusion

Using IGRAs for diagnosis of active TB in a setting like India results in tremendous overtreatment of people without TB, and substantial incremental cost with little gain in health. These results support the policies by WHO and Standards for TB Care in India, which discourage the use of IGRAs for the diagnosis of active TB in India and similar settings.

Translating genomics research into control of tuberculosis: lessons learned and future prospects

Genomics research has enabled crucial insights into the adaptive evolution of Mycobacterium tuberculosis as an obligate human pathogen. Here, we highlight major recent advances and evaluate the potential for genomics approaches to inform tuberculosis control efforts in high-burden settings.

The impact of novel tests for tuberculosis depends on the diagnostic cascade

The role of novel tests for TB in reducing morbidity and mortality depends on the system in which they are implemented.

A user-friendly, open-source tool to project impact and cost of diagnostic tests for tuberculosis

Most models of infectious diseases, including tuberculosis (TB), do not provide results customized to local conditions. We created a dynamic transmission model to project TB incidence, TB mortality, multidrug-resistant (MDR) TB prevalence, and incremental costs over 5 years after scale-up of nine alternative diagnostic strategies. A corresponding web-based interface allows users to specify local costs and epidemiology. In settings with little capacity for up-front investment, same-day microscopy had the greatest impact on TB incidence and became cost-saving within 5 years if delivered at $10/test. With greater initial investment, population-level scale-up of Xpert MTB/RIF or microcolony-based culture often averted 10 times more TB cases than narrowly-targeted strategies, at minimal incremental long-term cost. Xpert for smear-positive TB had reasonable impact on MDR-TB incidence, but at substantial price and little impact on overall TB incidence and mortality. This user-friendly modeling framework improves decision-makers' ability to evaluate the local impact of TB diagnostic strategies.

DOI:http://dx.doi.org/10.7554/eLife.02565.001

Tuberculosis is an infectious bacterial disease caused predominantly by the microorganism Mycobacterium tuberculosis. Although the number of deaths from tuberculosis has been falling in recent years, the disease still kills more than 1 million people every year, mainly in developing countries. Tuberculosis can be treated with antibiotics, but the emergence of bacteria that are resistant to existing drugs is threatening efforts to eradicate the disease.

Preventing the spread of tuberculosis is heavily dependent on accurate diagnosis of individuals with the disease. This is challenging because the initial symptoms are often mild, usually just a cough, which means that someone can spread the disease to many others over a period of several months before the symptoms become worse—fever, night sweats, and weight loss—and they realize that they are sick. Multiple diagnostic strategies are available, from the relatively low-tech—examining sputum samples under a microscope to detect tuberculosis bacteria—to more sophisticated tests that can detect bacterial DNA and determine whether the bacteria are drug-resistant in less than 2 hr.

Choosing which diagnostic strategy to adopt can be challenging because the optimal solution in a region will depend on the specific local conditions. To overcome this problem, Dowdy et al. have developed a computer program that enables decision-makers to input four key parameters that describe the tuberculosis situation in their region, and to obtain 5-year projections of the rate of new infections, mortality, and total costs likely to result from adopting any of nine different diagnostic strategies.

The four parameters are the number of new cases of tuberculosis each year (incidence), the proportion of new cases that are multi-drug resistant, the proportion of the adult population that has HIV, and the local costs of various diagnostic techniques and treatments. Since the entire computer program is written in a freely available open-source programming language (Python), any user can tweak these parameters to provide a more precise fit to their own region. Alternatively, the standard version of the program can be run directly from a website without any need to interact with computer code.

This model is the first to enable local decision-makers to evaluate the impact of different diagnostic strategies for tuberculosis under the conditions specific to their region. The model predicts, for example, that in areas where there is little money available for up-front investment, same-day microscopy analysis of sputum samples and starting patients on treatment is the most cost-effective strategy for reducing the rate of new infections. Given the wide variation in conditions within even small geographical areas, this more flexible approach should lead to the more efficient use of resources and may, ultimately, help to reduce the spread of tuberculosis.

DOI:http://dx.doi.org/10.7554/eLife.02565.002