Replacing smear microscopy for the diagnosis of tuberculosis: what is the market potential?

Abstract

To the Editor: Sputum smear microscopy (SSM) has been the cornerstone of tuberculosis (TB) diagnosis, and is mainly performed in peripheral microscopy centres attached to primary health centres where TB therapy can be administered. Although SSM is inexpensive and easy to perform with a limited infrastructure, the shortcomings are its relatively low sensitivity and its inability to detect drug-resistance. Thus, there is a need for a more sensitive technology that can replace microscopy [1, 2]. Several next-generation molecular diagnostics are under development with the specific intention of use in microscopy centres [3–5]. In a recent survey of 22 high-burden countries (HBCs), we showed that the conditions, equipment and expertise present in microscopy centres are challenging and need to be considered by product developers [6]. While the Xpert MTB/RIF (Cepheid Inc., Sunnyvale, CA, USA) assay is accurate, endorsed by the World Health Organization and is being implemented in many countries, it was not designed for use in peripheral microscopy centres [7, 8]. To assist product developers working on tests for use in microscopy centres, we have outlined the desirable test characteristics [1]. For companies to take on the challenge and invest in new diagnostics, an understanding of the potential market size is paramount [9]. A 2006 global TB diagnostics market analysis predicted that a smear replacement test applied at the level of peripheral clinics and microscopy centres would have a potential market size of 36.6 million tests per year in the 22 HBCs in 2020, assuming it would diagnose pulmonary, extrapulmonary and paediatric TB [10 …