Results for malaria RDT lot testing
Since it was first implemented in 2007, the malaria RDT lot testing programme has been experiencing a steady increase in workload (see graph). In 2011, the Global Fund’s Quality Assurance Policy for Diagnostic Products recommended malaria RDT lot testing to all of its grant recipients. This contributed to a rapid increase in demand, and lot testing has since been adopted by most major procurers. In 2014, the trend started to decrease slightly for the first time in seven years, and the 2015 demand will show if this indicates that a plateau phase has been reached.
The primary requesters of lot testing are RDT manufacturers, NGOs/IOs, and procurement agencies. According to data collected from lot testing requesters, the RDT lots submitted for testing in 2014 represented about 210 million RDTs distributed to 48 countries. Of these, 165 million RDTs (88%) were destined for distribution in sub-Saharan Africa where 90% of global malaria deaths occurred in 2013, showing a coherent distribution in terms of geographical needs.
Of the 927 RDT lots submitted for lot testing in 2014, none failed the initial assessment. 598 lots also underwent long-term stability testing after 18 months of storage at 37 degrees Celsius, of which one lot failed the testing both with P. falciparum and P. vivax samples at a density of 200 parasites per microliter of blood. Results provided to lot testing requesters support decisions for accepting or rejecting RDT lots, inform on the long term stability of products, and provide comments on observations made during interpretations of results, such as a red background, test line intensity, invalid results, and other anomalies, such as buffer evaporation. The latter observation was mainly seen in RDT single kits, and has led to the publication of a notice of concern by the WHO Prequalification of Diagnostics Department.
The low failure rate observed in lot testing is consistent with the fact that more than 99% of the RDTs submitted for lot testing are now from products that perform well, with a PDS* equal to or higher than 75% in the WHO Product Testing, according to the WHO recommendations for RDT procurement. Back in 2007, the percentage of submitted well-performing products was only 70%; since then, noticeable improvements in procurement practice have taken place. This means that the major procurers using the lot testing service are now selecting their RDTs based on the WHO recommendations and are using good quality RDTs for dissemination to the field.
The WHO-FIND lot testing programme currently tests only a proportion of RDT lots procured in the public sector. The RDTs submitted for evaluation are commonly from agencies with strict procurement criteria, so the ‘pass’ rate of these RDTs may not reflect the quality of all RDTs used globally. Similarly, when viewing a failure rate, it is important to consider the number of lots of this product that have been tested. Lot testing is designed to prevent very poorly performing lots from reaching the field. The sample size is insufficient to make fine distinctions in RDT performance: this is the role of the RDT Product Testing Programme.