Information given by websites selling home self-sampling COVID-19 tests: An analysis of accuracy and completeness

Objectives

To assess the accuracy and completeness of information provided by websites selling home self-sampling and testing kits for COVID-19.

Design

Cross-sectional observational study.

Setting

All websites (n = 27) selling direct to user home self-sampling and testing for COVID-19 (41 tests) in the UK (39 tests) and US (2 tests) identified by a website search on 23 ^rd May 2020.

Main outcome measures

Thirteen predefined basic information items to communicate to a user, including who should be tested, when and how testing should be done, test accuracy, and interpretation of results.

Results

Many websites did not provide the name or manufacturer of the test (32/41; 78%), when to use the test (10/41; 24%), test accuracy (12/41; 29%), and how to interpret results (21/41; 51%). Sensitivity and specificity were the most commonly reported test accuracy measures (either reported for 27/41 (66%) tests); we could only link these figures to manufacturers’ documents or publications for four (10%) tests. Predictive values, most relevant to users, were rarely reported (five [12%] tests reported positive predictive values). For molecular virus tests, 9/23 (39%) websites explained that test positives should self-isolate, and 8/23 (35%) explained that test negatives may still have the disease. For antibody tests, 12/18 (67%) websites explained that testing positive does not necessarily infer immunity from future infection. Seven (39%) websites selling antibody tests claimed the test had a CE mark, when they were for a different intended use (venous blood rather than finger-prick samples).

Conclusions

At the point of online purchase of home self-sampling COVID-19 tests, users in the UK are provided with incomplete, and in some cases misleading information on test accuracy, intended use and test interpretation. Best practice guidance for communication about tests to the public should be developed and enforced for online sales of COVID-19 tests.

Strengths and Weaknesses

• We believe this is the first research on accuracy of information provided by websites selling tests for COVID-19, where users may put themselves or others at increased risk of transmission if results are misinterpreted.

• We duplicated processes of searching and data extraction to minimise bias

• Using pre-specified criteria, we found evidence that websites selling home self-sampling COVID-19 tests provided incomplete and inaccurate information on test accuracy and interpretation of test results at the point of purchase.

• We developed basic guidance on what should be communicated when selling tests, including the type of test; situations when the test should be used; the time when the test should be done and details of how it should be done; the name of the test and details from clinical accuracy studies; evidence of compliance with regulatory approvals; explanation of test results using accessible and relevant metrics such as predictive values; and guidance to the interpretation and actions based on results.

• We only included websites from the UK and US, so whilst the principles of what should be communicated apply to all countries, the results about data completeness are not generalisable beyond the UK and US.