Rapid chromatographic immunoassay-based evaluation of COVID-19: A cross-sectional, diagnostic test accuracy study & its implications for COVID-19 management in India

Abstract

Background & objectives: Coronavirus disease 2019 (COVID-19) has so far affected over 41 million people globally. The limited supply of real-time reverse transcription-polymerase chain reaction (rRT-PCR) kits and reagents has made meeting the rising demand for increased testing incompetent, worldwide. A highly sensitive and specific antigen-based rapid diagnostic test (RDT) is the need of the hour. The objective of this study was to evaluate the performance of a rapid chromatographic immunoassay-based test (index test) compared with a clinical reference standard (rRT-PCR). Methods: A cross-sectional, single-blinded study was conducted at a tertiary care teaching hospital in north India. Paired samples were taken for RDT and rRT-PCR (reference standard) from consecutive participants screened for COVID-19 to calculate the sensitivity and specificity of the RDT. Further subgroup analysis was done based on the duration of illness and cycle threshold values. Cohen's kappa coefficient was used to measure the level of agreement between the two tests. Results: Of the 330 participants, 77 were rRT-PCR positive for SARS-CoV-2. Sixty four of these patients also tested positive for SARS-CoV-2 by RDT. The overall sensitivity and specificity were 81.8 and 99.6 per cent, respectively. The sensitivity of RDT was higher (85.9%) in participants with a duration of illness ≤5 days. Interpretation & conclusions: With an excellent specificity and moderate sensitivity, this RDT may be used to rule in COVID-19 in patients with a duration of illness ≤5 days. Large-scale testing based on this RDT across the country would result in quick detection, isolation and treatment of COVID-19 patients.

Comparison of the Rapid Antigen Testing Method With RT-qPCR for the Diagnosis of COVID-19

“…This indicates the infection was low grade that might have resulted in the low sensitivity of the test results. A similar pattern was observed in the study conducted by Gupta et al in New Delhi [ 15 ]. This indicates the antigen test is not a reliable in low-viral-load cases many of which are asymptomatic.…”

“…Many studies conducted in India and abroad found the sensitivity and specificity to be higher as compared to the current study [ 11 - 15 ]. The reported sensitivity varied from as high as 93.9% to as low as 70.0% and the specificity varied from as high as 100% to as low as 92.0%.…”

“…The low sensitivity and specificity may be attributed to the low prevalence in the current study population as compared to the other studies. Although there is a wide variability in the sensitivity and specificity of the RDT, the kits are suitable for point-of-care testing and thus can have wide applicability in pandemic control [ 15 ].…”

Antigen tests for COVID-19

“…Various other reports regarding the performance of the commercially available rapid antigen tests have been published from Germany [39], India [40], Italy [41], Spain [42,43], Thailand [44], and USA [45]. All these results indicated that the sensitivity was decent (70.6%-100%) and the specificity was high (96%-100%).…”

Update of European Society of Clinical Microbiology and Infectious Diseases coronavirus disease 2019 guidelines: diagnostic testing for severe acute respiratory syndrome coronavirus 2

“… In patients with signs and symptoms compatible with COVID-19, we suggest the use of laboratory based NAAT in nasopharyngeal samples versus rapid antigen detection testing in nasopharyngeal samples for the diagnosis of COVID-19. Weak against Very low [ 4 , 5 , 16 , 106 , [17] , [18] , [19] , [20] , [21] , [22] , [23] , [24] , [25] , 6 , [26] , [27] , [28] , [29] , [30] , [31] , [32] , [33] , [34] , [35] , 8 , [36] , [37] , [38] , [39] , [40] , [41] , [42] , [43] , [44] , [45] , 10 , [46] , [47] , [48] , [49] , [50] , [51] , [52] , [53] , [54] , [55] , 11 , [56] , [57] , [58] , [59] , [60] , [61] , [62] , [63] ...…”