Wednesday, 23 September

COVID-19: FDA using wrong methodology to evaluate RDTs – Lab scientists

Health News
GAMLS has said the current method of evaluation of COVID-19 antibody RDTs in the country is flawed

The Ghana Association of Medical Laboratory Scientists (GAMLS) has said the current method of evaluation of COVID-19 antibody RDTs in the country is flawed and has called on the Food and Drugs Authority (FDA) to review its methodology.

This was contained in a statement by GAMLS on Thursday, 13 August 2020.

The association said: “It is deeply concerned about the criteria being currently used for the validation of antibody rapid diagnostics test kits (RDTs) for COVID-19 testing in Ghana.”

According to GAMLS, “The continuous use of Real-Time Polymerase Chain Reaction (RT-PCR), the so-called ‘gold standard’, as a yardstick for antibody RDTs validation, makes it almost impossible for any COVID-19 antibody RDTs to get approval from the regulator, as the method being used amounts to comparing oranges to apples instead of apples to apples.”

GAMLS explained that: “Scientifically, methods evaluation or validation of a test method, test kit/reagent among others, is done using the so-called ‘gold standard’ within the same class of the item being evaluated. In method validation, the first principle is to always compare like to like: i.e., molecular to molecular detection methods (RT-PCR to RT-PCR) and serological to serological (RDT to RDT). The second consideration is where methods or test kits/reagents of different classes are evaluated, the highest and most superior gold standard available is used.”

GAMLS, thus, strongly advised the Food and Drugs Authority (FDA) and its partners to “review and use the appropriate method to evaluate and validate antibody RTDs for COVID-19 testing in order not deny Ghanaians the benefits of using RDTs for screening and diagnostic of the disease.”

GAMLS referred to the FDA’s update to Ghanaians on Tuesday, 28 July 2020 “on the status of COVID-19 antibody rapid diagnostic test (RDT) kits submitted by various vendors for evaluation and approval for COVID-19 testing in Ghana”.

“In the briefing addressed by the Chief Executive Officer (CEO), Mrs. Delese Mimi Darko, the regulatory body indicated that all 34 RDTs received failed to meet the sensitivity requirement of 99% when compared to the ‘gold standard’. The CEO further explained that due to the unavailability of a ‘gold standard’ for antibody tests, the RT-PCR ‘gold standard’ was used to validate the COVID-19 antibody RDTs.”

GAMLS noted that while it “appreciates and commends the FDA’s efforts in ensuring that test kits, reagents, equipment and other related consumables approved for use in Ghana are of high quality and meet the required standards,” it is its “professional opinion that the current method being used in the evaluation of COVID-19 antibody RDTs is flawed and should be reviewed to ensure that Ghana takes advantage of the many benefits that RDTs offer in screening and diagnoses of COVID-19.

The association reiterated that: “Though the World Health Organization (WHO) and Centre for Disease Control (CDC) have not recommended the use of any particular RDT for COVID-19 testing”, adding that: “Countries are advised to evaluate available RDTs and develop testing algorithms that best suits their need”.

GAMLS continued that as a professional body, it strongly believes “that COVID-19 antibody RDTs have their place in the screening of persons exposed to the virus and can provide the country with a more accurate estimate of the true burden of the pandemic in Ghana.”


It, therefore, encouraged “the FDA to consider reviewing its current validation methodology”.

It said reputable international organisations such as FIND and others have recommended the use of a comparator gold standard -- an intermediate method used to bridge the gap between RT-PCR and RDT for the validation of COVID-19 RDTs.

It further noted that: “There is a misleading misconception that Ghana is using the highest standards to validate COVID-19 RDTs because they are been compared to RT-PCR. This in reality is counterproductive and results in falsely skewed results that creates the impression that the RDTs are of lower quality.

“The current results obtained may simply be due to the fact that the RDTs are compared to a far superior test methodology and not that the RDTs are necessarily not meeting the standard. One may ask why at least one of these RDTs have been validated with acceptable performance in other jurisdictions but are not meeting the sensitivity requirements in Ghana. What might be the problem? We strongly encourage the FDA to review its validation methodology.”

GAMLS further urged the “government, the Ministry of Health and the Ghana Heath Service to speed up processes to use the 130 GeneXpert testing devices to expand testing to other parts of the country as has been previously promised.”

It also reminded the general public to” respect the directives by the authorities and to strictly adhere to all the safety protocols and maintain good personal hygiene practices to protect themselves and their families, and to protect frontline workers and their families.”