Testing for COVID-19: a 2023 update

Communicating the Imperfect Diagnostic Accuracy of COVID-19 Rapid Antigen Self-Tests: An Online Randomized Experiment

OBJECTIVE

To investigate the potential impacts of optimizing coronavirus disease 2019 (COVID-19) rapid antigen test (RAT) self-testing diagnostic accuracy information.

DESIGN

Online randomized experiment using hypothetical scenarios: in scenarios 1 to 3 (RAT result positive), the posttest probability was considered to be very high (likely true positives), and in scenarios 4 and 5 (RAT result negative), the posttest probability was considered to be moderately high (likely false negatives).

SETTING

December 12 to 22, 2022, during the mixed-variant Omicron wave in Australia.

PARTICIPANTS

Australian adults. Intervention: diagnostic accuracy of a COVID-19 self-RAT presented in a health literacy-sensitive way; usual care: diagnostic accuracy information provided by the manufacturer; control: no diagnostic accuracy information.

MAIN OUTCOME MEASURE

Intention to self-isolate.

RESULTS

A total of 226 participants were randomized (control n = 75, usual care n = 76, intervention n = 75). More participants in the intervention group correctly interpreted the meaning of the diagnostic accuracy information (P = 0.08 for understanding sensitivity, P < 0.001 for understanding specificity). The proportion who would self-isolate was similar across scenarios 1 to 3 (likely true positives). The proportion was higher in the intervention group than in the control for scenarios 4 and 5 (likely false negatives). These differences were not statistically significant. The largest potential effect was seen in scenario 5 (dinner party with confirmed cases, the person has symptoms, negative self-RAT result), with 63% of the intervention group and 49% of the control group indicating they would self-isolate (absolute difference 13.3%, 95% confidence interval: -2% to 30%, P = 0.10).

CONCLUSION

Health literacy sensitive formatting supported participant understanding and recall of diagnostic accuracy information. This may increase community intentions to self-isolate when there is a likely false-negative self-RAT result. Trial registration: Australia New Zealand Clinical Trial Registry (ACTRN12622001517763).

HIGHLIGHTS

Community-based diagnostic accuracy studies of COVID-19 self-RATs indicate substantially lower sensitivity (and higher risk of false-negative results) than the manufacturer-supplied information on most government public Web sites.This online randomized study found that a health literacy-sensitive presentation of the imperfect diagnostic accuracy COVID-19 self-RATs supported participant understanding and recall of diagnostic accuracy information.Health literacy-sensitive presentation may increase community intentions to self-isolate after a negative test result where the posttest probability is still moderately high (i.e., likely false-negative result).To prevent the onward spread of infection, efforts to improve communication about the high risk of false-negative results from COVID-19 self-RATs are urgently needed.

COVID-19 rapid antigen tests approved for self-testing in Australia: published diagnostic test accuracy studies and manufacturer-supplied information. A systematic review

OBJECTIVES

To review evaluations of the diagnostic accuracy of coronavirus disease 2019 (COVID-19) rapid antigen tests (RATs) approved by the Therapeutic Goods Administration (TGA) for self-testing by ambulatory people in Australia; to compare these estimates with values reported by test manufacturers.

STUDY DESIGN

Systematic review of publications in any language that reported cross-sectional, case-control, or cohort studies in which the participants were ambulatory people in the community or health care workers in hospitals in whom severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was suspected, and the results of testing self-collected biological samples with a TGA-approved COVID-19 RAT were compared with those of reverse transcription-polymerase chain reaction (RT-PCR) testing for SARS-CoV-2. Estimates of diagnostic accuracy (sensitivity, specificity) were checked and compared with manufacturer estimates published on the TGA website.

DATA SOURCES

Publications (to 1 September 2022) identified in the Cochrane COVID-19 Study Register and the World Health Organization COVID-19 research database. Information on manufacturer diagnostic accuracy evaluations was obtained from the TGA website.

DATA SYNTHESIS

Twelve publications that reported a total of eighteen evaluations of eight RATs approved by the TGA for self-testing (manufacturers: All Test, Roche, Flowflex, MP Biomedicals, Clungene, Panbio, V-Chek, Whistling) were identified. Five studies were undertaken in the Netherlands, two each in Germany and the United States, and one each in Denmark, Belgium, and Canada; test sample collection was unsupervised in twelve studies, and supervised by health care workers or researchers in six. Estimated sensitivity with unsupervised sample collection ranged from 20.9% (MP Biomedicals) to 74.3% (Roche), and with supervised collection from 7.7% (V-Chek) to 84.4% (Panbio); the estimates were between 8.2 and 88 percentage points lower than the values reported by the manufacturers. Test specificity was high for all RATs (97.9-100%).

CONCLUSIONS

The risk of false negative results when using COVID-19 RATs for self-testing may be considerably higher than apparent in manufacturer reports on the TGA website, with implications for the reliability of these tests for ruling out infection.