Impact assessment of diagnostic tools for multi-drug resistant and (MDR-TB) drug sensitive tuberculosis (TB) in the Philippines

While the Philippines has made great strides in Tuberculosis (TB) control, it continues to be the 6th largest cause of mortality and morbidity in the country. There are around 27,000 deaths annually and an estimated 290,000 new cases of TB each year at an incidence rate of 292 per 100,000. The percentage of TB cases with Multi-drug resistance (MDR-TB) is 2% for new cases and 21% for retreatment cases. The World Health Organization (WHO) estimate that only 12-16% of actual MDR-TB cases are detected of which only two-thirds are successfully treated. In the largest province in the country (Cavite) case detection rates have been improving, however only 35% of the estimated smear-positive MDR-TB cases are currently detected.

Improvement in access to accurate diagnosis is necessary to reduce further the burden of TB/MDR-TB. Encouragingly there is a pipeline of new diagnostic tools becoming available. For example, Xpert MTB/RIF is a new technology recommended by the World Health Organization that has the potential to make a significant difference to diagnosis of TB and MDR-TB in high burden countries like the Philippines. At the present time there are just 16 sites that perform the Xpert MTB/Rif test scattered over the different regions of the country. If the benefits of these developments are to be realized in the Philippines it is essential an appropriate strategy on scale-up is developed. However, more work is needed on the data to go beyond test accuracy in order to promote rational, evidence-based decision-making on uptake and implementation. TB diagnostics are not implemented in isolation, but are always part of an algorithm that operates in conjunction with other diagnostic approaches, such as empirical treatment or radiology. Computer modelling is an approach that can bring together the published and national data to provide policy makers with the evidence they need to support rational decisions.

In this study a number of alternative diagnostic options will be researched using an innovative modelling approach to project patient and health system outcomes including understanding the cost effectiveness of alternative options. Working with the National TB programme (NTP) of the Philippines these projections will be used to develop a strategy on scale up of new diagnostics in the largest province of the Philippines (Cavite). Filipino researchers from the De la Salle Health Sciences Institute (DLSHSI) will also be trained and equipped to conduct research in other provinces and on other diagnostic tools as they become available.

Our aim is to equip Filipino researchers and the NTP of the Philippines with a tested impact assessment approach that can be used to project the impact of new diagnostic tools and algorithms for MDR-TB and TB. Thus enabling policy makers to make rational and appropriate decisions on the scale-up of new diagnostic tools across the country. The approach used in this study has the potential to be applied in many other contexts around the world where TB and MDR-TB is a major barrier to public health and therefore economic development.

The objective of the research is to support the cost-effective roll-out of new tools and algorithms for the diagnosis of tuberculosis (TB) and multi-drug resistant TB (MDR-TB) in the Philippines. This will lead to improvements to TB/MDR-TB case detection and cure in the Philippines and promote the economic development and welfare of the country. The tools investigated will include the molecular test Xpert MTB/RIF and new point of care tests under development. The research programme will have 5 components:
1. Data collation- Data on the infrastructure, performance, and costing of the processes for TB and MDR-TB diagnosis and treatment will be collated. The sequence of events that patients follow in order to be diagnosed and start appropriate treatment will be mapped.
2. Model development- A computer model of the patient pathways using the innovative Virtual Implementation modelling approach will be developed. The approach produces a dynamic and visual representation of the pathways and will be used to project patient and health system outcomes. The model will be tested using data from Cavite province.
3. Cost effectiveness analysis- Outputs from the model will be used to estimate the incremental cost effectiveness of alternatives (Cost per Disability Adjusted Life Year (DALY) averted).
4. Strategy development - Working with policy makers from the National TB Programme (NTP) a strategy for the scale-up of new diagnostic tools and algorithms will be developed for Cavite province that takes account of the projected impacts and cost effectiveness of each option.
5. Capacity Building & Dissemination- An easy to use version of the model will be made available to the NTP and the De la Salle Health Sciences Institute (DLSHSI) using WITNESS software (www.lanner.com/en/). Training and support will be provided so researchers and the NTP can develop a strategy for new diagnostics in other provinces of the Philippines. Manuscripts will be submitted for publication.

The following groups will benefit from this research:-

1. Filipino research organisations - Through the research, new skills and approaches to impact assessment will be developed. Training will be provided. New models will be deployed that can be used in the future as new diagnostic technologies are developed. De La Salle Health Institute (DLSHSI) will be involved in writing manuscripts and publishing the research of this project.

2. The National TB programme (NTP) and policy makers within the Ministry of Health in the Philippines - The research will result in the development of a strategy for the roll-out of new diagnostics in Cavite province and beyond. The strategy will be supported by evidence of impact on patients and the health system.

3. Patients in the Philippines with TB/MDR-TB that need to access rapid diagnostic tests - The implementation of the strategy developed will improve access to rapid diagnostics for TB/MDR-TB in the Philippines. This will likely to start in Cavite province and then move onto the rest of the country.

4. Developers of new diagnostics for TB/MDR-TB - Demand for those diagnostics that are identified as being cost effective in the Filipino context will be created. Evidence will be presented which helps other developers to identify the key characteristics necessary to maximise cost effective impact.

5. Economic development of the Philippines - Among the 8 disease priority areas in this Call, it is tuberculosis that has the biggest impact in terms of mortality, morbidity ,economic costs and burden of disease (exceeding 1.3 million DALYs per year) afflicting the poorest as well as the most productive age groups. Access to quick and accurate diagnosis remains the biggest challenge especially among MDR-TB and smear-positive cases. Among the top 10 countries globally with the highest MDR TB burden, the Philippines ranked 7th with 8,500 estimated MDR TB cases among notified cases3. This project's objective of developing a model for assessing the deployment of new diagnostics including Xpert MTB/RIF in Cavite, the most populous province in the Philippines, will greatly advance TB control in the Philippines. Early detection would reduce treatment delay, save thousands of lives and improve the economic plight of hundreds of thousands of Filipinos.

6. The wider research community in Asia-Pacific region and beyond - Research will be published in high impact journals that will act as a stimulus to further productive research into TB/MDR-TB, XDR-TB, diagnostics, and the use of patient pathway modelling in TB and other priority diseases.