E-DRUG: Quality of Malaria Tests in WHO Sources & Prices (4)
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We note the letter from Christa Hook and Daniel Berman of MSF (20 January 2005)
regarding the Joint WHO-RBM-UNICEF-PSI-MSH publication of sources and prices of
selected products for Prevention, Diagnosis and Control of Malaria. They raise
some important issues regarding the purchase and use of malaria rapid
diagnostic tests.
As stated by MSF, the booklet gives names, format, and contact details of all
diagnostic manufacturers. All known manufacturers were contacted, and those who
responded were listed in the publication. The booklet provides advice on
purchasing and use of malaria RDTs, with links to further information. As MSF
would be aware, there is much published data on trials and use of malaria RDTs,
including evidence of both successful and unsuccessful use of the same
products. However, the quality of these studies is variable. Furthermore,
variation in performance may result from many factors, including variation in
quality at manufacture, environmental damage to RDTs after purchase, variation
in target antigen, and quality of published studies. Thus, publishing reliable
information on the quality of tests, that can be extrapolated to most
situations of potential use, is not straight-forward. WHO is developing a
product testing programme for malaria RDTs ate present that will provide data
to enable such information to be published, is building capacity for testing of
quality after purchase, and is actively seeking funds to further this work.
As noted by MSF, the publication of data on a particular product by WHO is
often taken as a sign of endorsement of that product. However, the Sources and
Prices booklet includes a clear disclaimer stating that the publication does
not constitute an endorsement or warranty of the fitness of any product.
Publication of data on heat stability and other aspects of RDT quality provided
by manufacturers has been considered. However, WHO is aware that in some cases
this is unreliable, and it has therefore been decided not to include it.
Evidence of good manufacturing practice, though not a marker of product
effectiveness, is a useful guide to quality. As manufacturers work in a variety
of jurisdictions, a variety of standards are in use (e.g. CE Mark,
ISO13485:2003, FDA and other certifications) and their relevance to product
effectiveness varies. WHO is in the process of finalizing an appropriate list
of standards. WHO will then give manufacturers a period of notification to
provide evidence of relevant certification prior to using these standards when
publishing lists of manufacturers. It is important for availability of
affordable, good quality products in endemic countries that manufacturers are
not wrongly excluded.
In the meantime, WHO strongly recommends that purchasers request evidence of
temperature stability testing and successful use from manufacturers during the
procurement process, and do not purchase from manufacturers who can not provide
such data. While it is impossible for WHO to verify the quality of such data at
present, WHO is continuing to develop a transparent evidence-based product
testing/prequalification system. This will include a representative panel of
well-characterized parasites that will allow prediction of sensitivity and
specificity in various geographical settings, and accellerated stability
testing.
After purchase, monitoring of quality of RDT products and their use should
continue. WHO provides further recommendations on this in the Sources and
Prices booklet and in publications listed in the booklet and on
www.wpro.who.int/rdt .
David Bell
Malaria diagnostics
Western Pacific Regional Office
World Health Organization
P.O. Box 2932
Manila, Philippines
Ph: +63 2 5289756
Fax: +63 2 5211036
Roll Back Malaria Department
World Health Organization,
20 avenue Appia,
1211 Geneva 27,
Switzerland
Fax: +41 (22) 791 4824
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