Understanding False Negatives in Lateral Flow Tests: Common Myths and Facts

Since there are techniques to get a false positive, is there a way to get a false negative in a Lateral Flow Test (LFT)? This question often arises in discussions surrounding the accuracy of rapid diagnostic tests. The LFTs assume and rely on the subject being sensible, intelligent, and honest enough to do the test correctly, log the result, and understand the potential consequences of cheating. However, numerous factors can impact the reliability of these tests, especially in the context of a pandemic.

Prevalence of False Negatives in LFTs

According to a Cochrane review, lateral flow tests are significantly more likely to give false negative results. In people with confirmed COVID-19, these tests correctly gave a positive result to an average of 72 out of 100 people with symptoms. They also correctly identified 58 out of 100 people without symptoms. This means that 28 out of 100 people with symptoms who tested negative may have had an incorrect reading. Additionally, 42 out of 100 people without symptoms who tested negative may also have had an incorrect reading.

Factors Influencing LFT Accuracy

The accuracy of LFTs is influenced by several factors, including the timing of the test relative to symptom onset. Research suggests that tests used in the first week after symptoms first developed are most accurate. This is because people typically have the highest viral load in their system during the first few days after infection. Viral load refers to the amount of virus present in the body.

The Necessity for Prudence and Accuracy

The LFTs are designed to be user-friendly and require minimal interference from the user. However, any misinformation or inadequate reporting from the user can impact the test's accuracy. It is crucial that individuals read and follow the instructions carefully to minimize the risk of false negatives. While it may be tempting to rush the process or alter the results for any reason, the potential consequences are severe.

Conclusion

Understanding the potential for false negatives in LFTs is essential for ensuring the reliability of these diagnostic tools. While false positives can occur, the risk of false negatives is higher, with significant implications for public health. It is imperative that individuals adhere to the instructions provided with these tests, document their results accurately, and report any discrepancies to health authorities.

For more information on LFTs and their accuracy, consult reliable medical and scientific sources.

Keywords: Lateral flow test, false negative, false positive, COVID-19, virus detection