|Rapid Diagnostic Tests (RDTs)|
This report details the recommendations of a WHO informal consultation on malaria RDTs held in Manila in January 2003.
Early, rapid diagnosis of malaria is gaining increasing importance in health programs in endemic countries in response to increasing drug costs and recognition of the importance of early, correct treatment to the reduction in malaria morbidity and mortality. Blood-based diagnosis using lateral-flow immunochromatographic tests, commonly called rapid diagnostics tests (RDTs), offers great promise in extending rapid diagnosis to areas where traditional microscopy diagnosis is impractical. Since a previous World Health Organization (WHO) informal consultation reviewed this issue in 1999, there has been a rapid increase in both the use of RDTs and the number products available. Together with this has come the publication of a wide range of field and laboratory trials, often with conflicting or inconsistent results. Large-scale operational use has raised questions over the accuracy of current RDT technology in tropical conditions. As utilization of RDTs is likely to increase rapidly over the next few years, there is a clear and urgent need to address issues of quality of performance and appropriateness of use, particularly in remote endemic areas.
This report details the recommendations of a WHO informal consultation on malaria RDTs held in Manila in January 2003. The 2003 consultation reviewed progress in the development of malaria RDT quality assurance (QA) since the previous consultation in 1999, aimed to define an appropriate path for further QA development, and to clarify priorities for further research necessary to guide the large-scale use of RDTs.
The need for QA systems to maintain the quality of microscopy diagnosis of malaria is well established but the extent of implementation varies widely. Good QA processes for RDTs will greatly enhance their value to populations at risk and to health systems in endemic countries, providing the evidence necessary to permit greater reliance on RDT results as a guide to treatment.
The quality-assurance process must become an integral part of RDT budgets and implementation plans. Responsibility for overseeing QA processes, extending from post-purchase testing of RDTs to training and supervision of users and control of storage and transport, should be clearly defined and coordinated from a central level. A system of regional and referral laboratories, based on standard operating procedures currently being developed by WHO, should be developed. This would test RDTs after purchase and for the duration of shelf-life using quality control (QC) panels prepared from wild-type parasites. A model for this process has been defined. Further research and development are needed on quality control testing closer to the point of use of RDTs, possibly using antigen-containing wells, and on appropriate training and supervision systems for end-users. Affordable temperature monitoring is needed for transport and storage. Quality assurance processes must be transparent, and good communication with manufacturers and end-users during QA development is necessary.
There is also a significant need to improve the quality and flow of information on RDT testing and use and to develop a good evidence base to guide their introduction into health systems. Minimum standards for field trials of malaria RDTs were defined during the consultation and these should be disseminated to assist in the planning and interpretation of field and laboratory trials. There is a place for a large multicenter phase-three field trial to establish the capabilities of a range of RDT products targeted at endemic populations. Further studies are required on operational issues to improve blood-transfer methods and clarity of product instructions. Cost-benefit studies and assessment of the impact of RDTs on treatment seeking and treatment provision will guide implementation, but need to be tailored to local conditions. Guidelines for such assessments should be made available.
Adequate disclosure by manufacturers of technical capabilities, such as heat stability, is essential to guide purchasers in choosing products appropriate for use in remote tropical conditions. In turn, an improved method of disseminating information on available products and planned tendering processes is in the interests of all. A website under development by WHO should facilitate this information exchange and improve dissemination of information and guidelines on other aspects of RDT use.
Malaria RDTs have the potential to significantly improve the quality of malaria management as a complement to microscopy, providing accurate diagnosis in areas where this has been previously unavailable. Success in improving management will depend largely on the support systems set up to ensure continued RDT accuracy in the hands of end-users. There is a window of opportunity now to ensure that such support systems become embedded in routine practice.
Regional Office for the Americas of the World Health Organization