A University of Manchester study has highlighted the inconsistent and insufficient sensitivity of lateral flow tests for identifying people with COVID-19

Ian Gessey lateral flow test device covid test

A study from the University of Manchester suggests that lateral flow tests may not be meeting minimum performance standards set by the World Health Organization (WHO) and the UK’s Medicine and Healthcare products Regulatory Agency (MHRA). The findings cast doubt on the effectiveness of a recent Government policy that requires all secondary schools to provide on-site COVID-19 testing for pupils in an attempt to reduce transmission. Secondary schools, college, and universities have also been advised to continue twice-weekly testing for pupils.

For their study, published in BMJ Evidence-Based Medicine, researchers from the Faculty of Biology, Medicine, and Health at the University of Manchester and the Institute for Quality and Efficiency in Health Care in Cologne assessed the diagnostic accuracy of rapid point-of-care tests for the diagnosis of current severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infections in children under real-life conditions.

They highlighted that debate is ongoing as regards the potential benefits and harms of testing in education sites. In addition, the authors pointed out that sensitivity estimates of antigen tests in adult populations vary broadly, are substantially lower than manufacturers report, and that ‘performance in paediatric populations remain[s] unknown’.

To investigate the sensitivity and specificity of lateral flow tests in children, the researchers performed a systematic review and meta-analysis of studies from research databases and preprint servers between January 2020 and May 2021.

They identified for inclusion 12 peer-reviewed journal studies and five preprint studies, with the data from these studies—which compared antigen tests against polymerase chain reaction (PCR) tests—being pooled to measure diagnostic sensitivity and specificity.

The data covered a total of 6355 children, and eight antigen tests from six different brands. The collected data involved samples collected from the nose and throat in 11 of the test evaluations, the others only being collected from the nose. All but one of the studies involved sample collection by trained staff, the one other being by supervised sample.

Real-life antigen performance varies broadly

Overall, the evaluated tests had a sensitivity (how well a test picks up people who have a disease/infection) of 64.2%, and a specificity (how well a test picks up those who don’t have a disease/infection) of 99.1%.

The researchers went on to analyse the data comparing those children who were symptomatic and asymptomatic. They found that, based on 3413 symptomatic children in 13 studies, the pooled diagnostic sensitivity was 71.8% and the pooled diagnostic specificity was 98.7%.

For asymptomatic children, the pooled diagnostic sensitivity was 56.2% and the pooled diagnostic specificity was 98.6%, based on 2439 children in 10 studies.

The researchers commented that the ‘performance of current antigen tests in paediatric populations under real-life conditions varies broadly’, adding that ‘these observed differences in test performance between children with and without symptoms show that sensitivity and specificity are not inherent test characteristics.’

Minimum test performance requirements not satisfied

The researchers acknowledged some limitations to their study, including that the review was limited to eight tests—despite the fact that there are currently over 500 lateral flow tests on the market—and that inadequate reporting precluded quality assessment of most of the studies.

In addition, none of the included studies assessed sample collection by self-testing or by untrained people. They added that their findings may not be applicable to future SARS-CoV-2 variants, or to vaccinated children. 

The authors said: ‘Sensitivity estimates of antigen tests varied broadly among studies and were substantially lower than reported by manufacturers.’

They continued by pointing out that no test included in their review ‘fully satisfied the minimum performance requirements as recommended by WHO or the Medicines and Healthcare products Regulatory Agency’.

They pointed out that, although lateral flow tests extend testing capacity, complement PCR testing, and offer short turnaround of test results, they ‘come at the price of lower diagnostic accuracy’, which in turn increases the risk of missing cases and ‘may affect the planned purpose of the broad implementation of testing programmes’.

This article was originally published on Medscape, part of the Medscape Professional Network.

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Lead image: Ian Gessey/stock.adobe.com

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