Misinterpreted At-Home COVID-19 Test Results Affect Quarantines

Pharmacists might include some counseling with boxes of at-home COVID-19 test kits they sell. A new study finds that users often misinterpret the results and, in some cases, don’t quarantine when they should. Here is more information about how to advise users on interpreting the tests.

LEBANON, NH – Results of at-home COVID-19 self-test kits often are misinterpreted, and many users who should self-quarantine don’t do that, according to a new study.

The report in JAMA Internal Medicine looked at what happened when self-test users followed instructions from the Food and Drug Administration or guidances developed with decision science principles, or no instruction. The Dartmouth Institute for Health Policy and Clinical Practice-led researchers also assessed whether users chose to self-quarantine per federal recommendations or quarantine unnecessarily?

The randomized clinical trial of 360 U.S. adults determined that most misinterpreted the negative results of at-home self-tests because they failed to consider the implications of a high pretest probability of infection and ignored the federal self-quarantine recommendations.

“The findings of this randomized clinical trial indicate that people who use at-home COVID-19 self-test kits may fail to self-quarantine or may quarantine unnecessarily because they misinterpret the implications of test results,” the authors advise. “Redesigned instructions may increase the benefits and reduce the harms from at-home self-test kits.”

Background information in the article notes that the FDA authorized SARS-CoV-2 rapid at-home self-test kits for individuals with and without symptoms. It has not been known, however, how appropriately users interpret and act on the results of at-home COVID-19 self-tests, according to the researchers.

“The U.S. Food and Drug Administration (FDA) has prioritized home testing for SARS-CoV-2 to help people ‘take immediate action, based on their results, to protect themselves and those around them,’” the study notes.

The authors point out, “Although COVID-19 at-home test kits provide results within 30 minutes, they test for viral antigens, ie, they are less sensitive (ie, have more false negatives) than PCR (polymerase chain reaction) tests, which have an estimated clinical sensitivity of approximately 70%.5,6 Therefore, users with a high pretest probability of disease should still quarantine even after receiving a negative test result. If users ignore that probability, a negative test result may encourage behavior that is risky to them and others.”

Participants in the study, who were recruited in April 2021 to complete an online survey on their interpretation of at-home COVID-19 self-test results, were given 1 of 3 instruction types and were presented with 1 of 4 risk scenarios. Respondents were paid $5 and had a median survey completion time of 8.7 minutes. Data analyses were performed from June to July 2021.

Their choices included:

  • the FDA-authorized instructions (authorized),
  • the intervention instructions (intervention) designed using decision science principles,
  • or no instructions (control).

Participants also faced 4 scenarios: 3 with a high pretest probability of infection (COVID-19 symptoms and/or a close contact with COVID-19) and 1 with low pretest probability (no symptoms and no contact).

“In this study, we asked people how they would respond to the results of a home test kit in scenarios with high or low pretest probabilities of COVID-19. Participants chose from 5 response options ranging from “take no precautions” to “stay at home all the time, without exceptions, and avoid contact with others, including others in the household,” according to the authors. ”We treated this last option as the response most closely aligned with the recommendation of the US Centers for Disease Control and Prevention (CDC) for individuals with a positive test result or a negative test result with a high pretest probability of disease.”

The study team set out to determine how users of at-home COVID-19 self-test kits actually interpret and act on results when given instructions authorized by the FDA, instructions based on decision science principles, or no instructions.

“We communicated pretest probabilities by asking participants to imagine having COVID-like symptoms and/or having been in close contact with actively infected patients,” the authors state. “We asked what actions they would take, in terms that could be compared with CDC recommendations.”

After excluding 22 individuals who completed the survey too quickly, the responses of 338 participants were included in the analysis. The respondents had a median age of 38, 46% were women and 64% had a college degree or higher.

Results indicate that, given a positive test result, 95% (322 of 338; 95% CI, 0.92 to 0.97) of the participants appropriately chose to quarantine no matter the instructions they had received.

On the other hand, according to the researchers, given a negative test result, participants in the high pretest probability scenarios were more likely to fail to quarantine appropriately with the authorized instructions (33%) than with the intervention (14%; 95% CI for the 19% difference, 6% to 31%; P = .004) or control (24%; 95% CI for the 9% difference, −4% to 23%; P = .02).

In the low pretest probability scenario, the percentage choosing unnecessary quarantine was more elevated with the authorized instructions (31%) than with the intervention (22%; 95% CI for the 9% difference, −14% to 31%) or control (10%; 95% CI for the 21% difference, 0.5% to 41%), although neither comparison was statistically significant (P = .05 and P = .20 respectively).

“The findings of this randomized clinical trial indicate that at-home COVID-19 self-test kit users relying on the authorized instructions may not follow the Centers for Disease Control and Prevention’s quarantine recommendations, producing unintended risks and unnecessary disruptions,” the authors conclude. “ Redesigned instructions that follow decision science principles may improve compliance.”

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