Comparing different technologies for active TB case-finding among the homeless: a transmission-dynamic modelling study

Determining the value of TB active case-finding: current evidence and methodological considerations

Active case-finding (ACF) is an important component of the End TB Strategy. However, ACF is resource-intensive, and the economics of ACF are not well-understood. Data on the costs of ACF are limited, with little consistency in the units and methods used to estimate and report costs. Mathematical models to forecast the long-term effects of ACF require empirical measurements of the yield, timing and costs of case detection. Pragmatic trials offer an opportunity to assess the cost-effectiveness of ACF interventions within a 'real-world´ context. However, such analyses generally require early introduction of economic evaluations to enable prospective data collection on resource requirements. Closing the global case-detection gap will require substantial additional resources, including continued investment in innovative technologies. Research is essential to the optimal implementation, cost-effectiveness, and affordability of ACF in high-burden settings. To assess the value of ACF, we must prioritize the collection of high-quality data regarding costs and effectiveness, and link those data to analytical models that are adapted to local settings.

Using molecular testing and whole-genome sequencing for tuberculosis diagnosis in a low-burden setting: a cost-effectiveness analysis using transmission-dynamic modelling

BACKGROUND

Despite progress in TB control in low-burden countries like England and Wales, there are still diagnostic delays. Molecular testing and/or whole-genome sequencing (WGS) provide more rapid diagnosis but their cost-effectiveness is relatively unexplored in low-burden settings.

METHODS

An integrated transmission-dynamic health economic model is used to assess the cost-effectiveness of using WGS to replace culture-based drug-sensitivity testing, versus using molecular testing versus combined use of WGS and molecular testing, for routine TB diagnosis. The model accounts for the effects of faster appropriate treatment in reducing transmission, benefiting health and reducing future treatment costs. Cost-effectiveness is assessed using incremental net benefit (INB) over a 10-year horizon with a quality-adjusted life-year valued at £20 000, and discounting at 3.5% per year.

RESULTS

WGS shortens the time to drug sensitivity testing and treatment modification where necessary, reducing treatment and hospitalisation costs, with an INB of £7.1 million. Molecular testing shortens the time to TB diagnosis and treatment. Initially, this causes an increase in annual costs of treatment, but averting transmissions and future active TB disease subsequently, resulting in cost savings and health benefits to achieve an INB of £8.6 million (GeneXpert MTB/RIF) or £11.1 million (Xpert-Ultra). Combined use of Xpert-Ultra and WGS is the optimal strategy we consider, with an INB of £16.5 million.

CONCLUSION

Routine use of WGS or molecular testing is cost-effective in a low-burden setting, and combined use is the most cost-effective option. Adoption of these technologies can help low-burden countries meet the WHO End TB Strategy milestones, particularly the UK, which still has relatively high TB rates.

Mobile X-ray outside the hospital: a scoping review

BACKGROUND

For several years mobile X-ray equipment has been routinely used for imaging in patients too unwell within the hospital, when transportation to the radiology department was inadvisable. Now, mobile X-ray examinations are also used outside the hospital. The literature describes that fragile patients may benefit from mobile X-ray, but we need to provide insights into the breadth, depth and gaps in a body of literature.

METHODS

The scoping review was performed by searching PubMed, Cinahl, Embase, EconLit and Health Technology Assessment. English-, Danish-, Norwegian-, German-, Italian-, French- and Swedish-language studies, published 1.1.2009-1.5.2020 about mobile X-ray outside the hospital were included. Participants were patients examined using mobile X-ray as the intervention. PRISMA was used when eligible to build up the review. To extract data from the selected articles, we used a structured summary table.

RESULTS

We included 12 studies in this scoping review. The results were divided into four topics:1. Target population 2. Population health 3. Experience of care and 4. Cost effectiveness. The main findings are that target population could be larger for instance including hospice patients for palliative care, group dwelling for people with intellectual disabilities, or psychiatric patients, population health may be improved, image quality seems to be good and mobile X-ray may be cost effective. Limitations of language, databases and grey literature may have resulted in studies being missed.

CONCLUSIONS

Mobile X-ray may be used outside hospital. There seems to be potential benefits to both patients and health care staff. Based on the published studies it is not possible to draw a final conclusion if mobile X-ray examination is a relevant diagnostic offer and for whom. Further studies are needed to assess the feasibility of use in fragile patients, also regarding staff, relatives and societal consequences and therefore the topic mobile X-ray needs more research.

Treatment of latent infection to achieve tuberculosis elimination in low-incidence countries

In a Perspective for the Tuberculosis Special Issue, Kevin Schwartzman and colleagues discuss the choices and implications for personal versus public health benefits when pursuing tuberculosis elimination in low-incidence countries.

Spatial and temporal projections of the prevalence of active tuberculosis in Cambodia

Introduction

Cambodia is among the 30 highest burden of tuberculosis (TB) countries. Active TB prevalence has been estimated using nationally representative multistage sampling that represents urban, rural and remote parts of the country, but the prevalence in non-sampled communes remains unknown. This study uses geospatial Bayesian statistics to estimate point prevalence across Cambodia, and demographic modelling that accounts for secular trends in fertility, mortality, urbanisation and prevalence rates to project the future burden of active TB.

Methods

A Bayesian hierarchical model was developed for the 2011 National Tuberculosis Prevalence survey to estimate the differential effect of age, sex and geographic stratum on active TB prevalence; these estimates were then married with high-resolution geographic information system layers to project prevalence across Cambodia. Future TB projections under alternative scenarios were then derived by interfacing these estimates with an individual-based demographic model.

Results

Strong differences in risk by age and sex, together with geographically varying population structures, yielded the first estimated prevalence map at a 1 km scale. The projected number of active TB cases within the catchment area of each existing government healthcare facility was derived, together with projections to the year 2030 under three scenarios: no future improvement, continualreduction and GDPprojection.

Conclusion

Synthesis of health and geographic data allows likely disease rates to be mapped at a high resolution to facilitate resource planning, while demographic modelling allows scenarios to be projected, demonstrating the need for the acceleration of control efforts to achieve a substantive impact on the future burden of TB in Cambodia.