Center for Global Health R&D Policy Assessment

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Point-of-Care Diagnostics for TB—The Devil’s in the Details

Reflections from recent conference, "TB Diagnostics in India: From importation and imitation to innovation"

Recently, I attended a conference in Bangalore, “TB Diagnostics in India: From importation and imitation to innovation” that brought together a diverse group that included public researchers, firms, venture capitalists, international donors and others to discuss the need for better TB diagnostics and the role that Indian firms might play in developing them. It was exciting to hear the lessons and experiences of established Indian diagnostic firms such as Span Diagnostics and the Tulip Group and the strategies of emerging players such as Bigtec and Achira Labs. Having such a rich pool of experts in one room led to lively discussions about the capabilities of Indian innovators, how the Indian R&D ecosystem is evolving, and what obstacles are holding back technologies for TB.

There were some disagreements amongst firms about what the true barriers to developing a TB diagnostic are and whether there is actually a business case to pursue them. In spite of these divergent opinions, they reached a clear consensus on one point: firms need a clear target product profile (TPP). Without a clear TPP, firms are unsure of what kind of technology to develop and what national TB programs and donors are willing to purchase.

Firms explained that the term “point-of-care” is often used without a consistent definition of what it truly means. Are policymakers willing to buy a test that is less sensitive and specific than sputum smear microscopy or nucleic acid amplification if it can be used in remote settings? How small should a point-of-care test be? How important is cost, and what is the trade-off between cost and accuracy? If current nucleic acid amplification technologies were cheaper, would that be enough? Should a point-of-care test simply rule out negative patients, so that patients with suspected TB can be referred to central laboratories? Is testing for MDR and XDR TB a high priority?

These questions, along with many others, highlight important trade-offs that drive the design of diagnostics. Ideally, a test would be 100% sensitive and specific among all patient populations and could also be easily used in remote locations. However, the current technological feasibility of creating such a test may deter firms from even trying to develop the perfect TB diagnostic. Some policymakers and clinicians suggest that there is no need for one catch-all TB test, but instead, for a few tests that could perform well in different clinical settings and among various patient groups (for example in areas with high HIV/AIDS or MDR/XDR prevalence). In this case, firms need a clear understanding of what the specifications should be for each test. It may be unnecessary to precisely answer all of the questions above, but firms must know the relative importance of these issues to policymakers and their procurement arms.

Since the conference focused on the role of Indian innovators, the needs of the government’s Revised National TB Control Programme were central to the discussion. Participants suggested that the program should convene officials from across the government of India to reach an agreement on what the government needs and is willing to purchase. This is a sensible idea that could help guide firms forward, and it could set an important precedent for other countries and international partners. A working group in India will help answer what Indian cities and villages need, but it cannot answer the question globally. How do the infrastructure and epidemiology of the disease in other high burden countries affect their diagnostic needs? These questions must be elevated to international policy discussions that result in clear guidelines.

The conference concluded on an optimistic note—many Indian innovators are interested in developing better TB diagnostics and are enthusiastic about working with the global health community. If policymakers can come together and set standards for what technologies they are willing to procure, then firms stand a much better chance of creating appropriate solutions.

* A discussion of the TPPs put forward in prize proposals for TB diagnostics can be found here.