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Rapid diagnostic tests (RDTs) for malaria could be greatly improved by a few simple measures, say researchers.
These include providing better information for health workers on how to use them effectively in the field and how to spot common errors, according to a study published in Malaria Journal last month (15 June).
"Inaccurate test results and poorly designed RDT kits were found to be limitations in the use of rapid diagnostic tests in malaria-endemic countries," Philippe Gillet, the lead author and a researcher at the Institute of Tropical Medicine in, Belgium told SciDev.Net.
The first Cochrane review of the tests — published last week (6 July) by the global non-governmental organisation the Cochrane Collaboration — found them to be "very accurate" when compared with laboratory-based microscopy or polymerase chain reaction tests. After analysing data from 74 studies it concluded that RDTs identify malaria correctly in 19 out of 20 cases.
But such reviews may overlook problems faced by health workers in real-life settings, said Piero Olliaro, a co-author of the review, who works on the Special Programme for Research and Training in Tropical Diseases at the WHO.
In 2007, more than 70 million such tests were carried out worldwide. They offer an easier and faster alternative to laboratory-based techniques that are often lacking in remote areas.
When used properly, RDTs can save lives and slow down drug resistance, because only people with confirmed malaria are treated.
For the Malaria Journal article, Gillet and his team analysed the accuracy of 873 tests from a Mozambique hospital.
They found a range of problems, including false-negative results in patients with high parasite densities because the display was too faint to see. Meanwhile, where health workers replaced the buffer — a liquid solution needed to run the tests — with water or buffer from another kit, three-quarters of tests gave false-positive results.
The study recommends providing better information about these limitations, providing more than one buffer in the kit, and including a warning in information leaflets.
David Bell, head of the malaria diagnostics programme at the Foundation for Innovative New Diagnostics, said manufacturers should explore the problems of faint displays "to ensure the tests work across the whole likely range of parasite densities".
An earlier study by Gillet’s team, also published in Malaria Journal (13 February), found that information on the packaging, labelling and information leaflets in 42 RDT kits from 22 manufacturers was difficult to read and often incorrect or incomplete.
"For a test to provide an accurate diagnosis, it has to be prepared properly and it has to be interpreted properly — and to do this you need very good instructions," said Bell. "What might be good instruction in a laboratory may not be adequate for a village health worker who has a different level of literacy and training."
Gillet suggested that the WHO or the European Union could demand improvements as part of the pre-qualification process, which certifies the quality of the tests and is needed for UN agencies to distribute them.
Olliaro agreed: "There is room for improvement to make these tests more user-friendly and perform better, particularly in the hands of health workers confronted with multiple tasks".
Malaria Journal doi: 10.1186/1475-2875-10-166 (2011)
Malaria Journal doi: 10.1186/1475-2875-10-39 (2011)
Cochrane Database of Systematic Reviews doi: 10.1002/14651858.CD008122.pub2 (2011)