Field evaluation of specificity and sensitivity of a standard SARS-CoV-2 antigen rapid diagnostic test: A prospective study at a teaching hospital in Northern Ghana

Abstract

The testing capacity for SARS-CoV-2 in Africa is rather limited. Antigen detection rapid diagnostic tests (Ag-RDTs) are a cheap and rapid alternative to reverse transcriptase-polymerase chain reaction (RT-PCR) tests, but there is little data about their performance under real life conditions in tropical countries. The objective of this study is to evaluate the performance of a standard Ag-RDT in a population of a major hospital in northern Ghana. Prospective, cross-sectional, blinded verification of the performance of the SD Biosensor Standard Q SARS-CoV-2 Ag-RDT under real life conditions in 135 symptomatic patients and 58 contacts of RT-PCR positives at Tamale Teaching Hospital in February 2021. Nasopharyngeal samples were taken under standard conditions and tested against RT-PCR in the hospital laboratory. 193 participants (median age 35 years, 109 male) were included into the study for which both RT-PCR test and Ag-RDT results were available. A total of 42 (22%) were RT-PCR positive. Of the 42 RT-PCR positives, 27 were Ag-RDT positive, resulting in a sensitivity of 64% (95% CI 49–79). Sensitivity among symptomatic patients was 58% (95% CI 38–78). 123 were identified Ag-RDT negatives of the 151 RT-PCR negatives, resulting in a specificity of 81% (95% CI 75–87). SARS-CoV-2 Ag-RDTs appear to have a rather low sensitivity and particularly a low specificity under real life conditions in Africa. The role of existing Ag-RDTs in countries with high-temperature climates and limited resources still needs more data and discussion.

Laboratory and field evaluation of the STANDARD Q and Panbio™ SARS-CoV-2 antigen rapid test in Namibia using nasopharyngeal samples

“…Although the STANDARD Q maintained a high specificity of 99% in the field, the test had a reduced sensitivity of 56%. Supporting our findings, field studies in African cohorts on the STANDARD Q conducted in Cameroon and Ghana reported an overall sensitivity of 59% and 64% respectively [ 21 , 22 ]. The high sensitivity observed in the laboratory might have been due the biased sampling of choosing an equal number of positive and negative samples compared to the randomness in the field of getting a much smaller proportion of individuals testing positive for COVID-19.…”

A Multicenter Clinical Diagnostic Accuracy Study of SureStatus, an Affordable, WHO Emergency Use-Listed, Rapid, Point-Of-Care Antigen-Detecting Diagnostic Test for SARS-CoV-2

“…Furthermore, the low performance in the group with <7 days of symptoms suggests underreporting or possibly different perceptions of the duration of symptoms in different cultures. Also, the impact of environmental conditions (i.e., high temperature and high humidity) could be considered ( 8 , 9 ). Of note, FIND repeatedly observed lower test sensitivity in the evaluations performed at the study site in India.…”

Accuracy of rapid point-of-care antigen-based diagnostics for SARS-CoV-2: an updated systematic review and meta-analysis with meta regression analyzing influencing factors

“…After removing duplicates, 11,462 articles were screened and 433 papers were considered eligible for full-text review. Of these, 259 were excluded because they did not present primary data or the Ag-RDT was not commercially available, leaving 174 studies to be included in the systematic review [16-189]. A list of the studies excluded and their reason for exclusion can be found in the Supplement (S4 Text).…”

“…At the end of the data extraction process, 21 studies were still in preprint form [16, 17, 21, 47, 50, 55, 58, 65, 69, 74, 84, 100, 116, 121, 129, 160, 167, 168, 173, 174, 186]. All studies were written in English, except for 3 in Spanish [53, 62, 134], 1 in Turkish [95], and 1 in French [153].…”

“…Further 20 studies were included from the FIND website [190][191][192][193][194][195][196][197][198][199][200][201][202][203][204][205][206][207][208][209] (Fig 1). At the end of the data extraction process, 21 studies were still in preprint form [16,17,21,47,50,55,58,65,69,74,84,100,116,121,129,160,167,168,173,174,186]. All studies were written in English, except for 3 in Spanish [53,62,134], 1 in Turkish [95], and 1 in French [153].…”