Assessing At-Home Testing Accuracy
Patients desire direct-to-consumer testing, but are the results this testing provides accurate and reliable?

The domain of clinical diagnostics seems to be expanding beyond the walls of the clinical laboratory, with patients’ awareness of and demand for at-home diagnostic testing increasing, in turn leading to an expansion in the direct-to-consumer (DTC) lab testing market.1 Although patients likely had some familiarity with at-home diagnostic testing—through at-home tests such as those for pregnancy or sexually transmitted infections—beforehand, the COVID-19 pandemic and the associated rapid antigen testing brought it to the forefront of the public consciousness.2 In particular, the pandemic testing response demonstrated the ease, speed, and comfort with which diagnostic results can be delivered and acted upon. But easier and faster doesn’t necessarily mean better, and questions remain regarding the accuracy and reliability of these tests, which are especially pertinent if patients begin to consider them a suitable alternative, instead of a potential addition, to the services provided by the clinical lab.
Often missing the mark
“The accuracy and reliability for at-home tests are possibly inferior to traditional lab tests,” says Z. Hugh Fan, director of the Microfluidics and BioMEMS laboratory of the University of Florida’s Interdisciplinary Microsystems Group. In 2018, researchers from Ambry Genetics published a study evaluating the accuracy of genetic variant identification by DTC testing performed on samples from 49 patients who had later been referred for testing at their clinical diagnostic lab.3 When they assessed the concordance of their confirmatory test results, 40 percent of the DTC-analyzed variants were found to be false positives by the clinical lab—of these, all but one were in genes related to cancer. Additionally, there were discrepancies in classification, with eight variants in five genes being classified as having “increased risk” (either in the DTC raw data or by third-party interpretation services) that Ambry and many other clinical laboratories determined to be “benign.”
These conclusions—that there is a need for validation of DTC raw data, and interpretation of DTC results by a qualified professional in the context of other factors—were supported by later research identifying that although DTC tests perform well in identifying common variants, their ability to identify a true positive declines dramatically as a variant’s frequency within the population also decreases.4 For very rare variants, with frequencies of less than 0.001 percent, only 16 percent of heterozygous genotypes were validated with sequencing data, a poor performance attributed to the single nucleotide polymorphism (SNP) chips many DTC genetic tests use. Genetic testing is not the only area in which DTC testing provides lesser results than traditional testing—even rapid antigen tests, such as those for COVID-19, can display notable differences in accuracy.
Although data comparing the accuracy of rapid antigen COVID-19 tests to lab testing for the disease was scarce at the height of the pandemic,5 research released since has demonstrated these tests to have an accuracy of 81 percent compared to reference laboratory reverse-transcription PCR testing.6 Although this accuracy is relatively high, it still represents a drop from laboratory testing accuracy, and highlights results that occurred under good conditions, with testing being carried out at a high-volume testing site by qualified and trained staff. Conversely, a study in which patients self-collected testing samples found the same COVID-19 rapid antigen test to have a far lower accuracy of 53.3 percent compared to its laboratory counterpart.7
But this doesn’t necessarily mean that all DTC diagnostic tests are inaccurate or unreliable to the point that they shouldn’t be used. “This is not always true, especially when at-home tests are sufficiently effective,” Fan explains. “For example, most at-home pregnancy tests are about 99 percent effective when used correctly.”
Making up the difference
So, what factors contribute the most to discrepancies in the results between at-home and traditional lab tests? “At-home tests need to be as simple as possible; they are most likely going to be operated by a non-trained person,” says Fan. “In contrast, traditional lab tests involve many steps, such as sample preparation and component separation, before detection. They are also operated by skilled personnel. Extensive automation may minimize the effects of these factors.” In addition to this, and the poor performance of some DTC testing components, such as the SNP chips used in at-home genetic tests, there are also concerns regarding the lack of quality and value of some consumer-driven tests, the result of the expansion of this sector to non-traditional laboratories made up of staff who may not be sufficiently qualified. This was pointed out by the Association for Diagnostics & Laboratory Medicine (ADLM) in a recent position statement regarding DTC laboratory testing.8 In particular, it highlights the argument of providing “health information” to customers that some companies, such as those in the wellness industry, use to evade regulatory oversight enabling them to continue providing tests that offer unreliable results to patients.
However, the ADLM also acknowledges that DTC testing has become an important tool, one that is opening new doors that enable patients to actively engage in their own health care, something that it supports—but under circumstances that mitigate potential harm. Its position is that DTC testing should only be carried out by reputable, CLIA-certified laboratories that also need to provide patients with sufficient, transparent, and understandable information about each test alongside expert help for interpreting results. Fan, who authored a review which identified advances in sample preparation and detection that are enhancing at-home point-of-care devices,9 agrees with the importance of this testing, especially for expanding the reach of basic diagnostics. He highlights some further ways that the reliability of this testing can be improved, particularly to prevent problems from occurring at the patient end of testing.
“Positive and/or negative control can be integrated into at-home tests to enhance the reliability. For example, the control line in the pregnancy test strips verifies that the test is working properly and that the sample was absorbed correctly,” he explains. “The accuracy and reliability of at-home tests can also be enhanced by integrating sample preparation and component separation, though extensive automation is required. As this testing continues to advance, video instruction may replace the paper pamphlet for helping the operator follow the procedure correctly, smartphones will likely play a role in imaging the test results and in telemedicine, and artificial intelligence may be used for enhancing the accuracy of at-home tests and for assisting the decision-making process.”
“It’s important that laboratorians keep an eye on the evolving at-home testing research and make innovative contributions to the field, because it can be impactful,” Fan adds.
References:
- BioSpace. Direct-to-Consumer Laboratory Testing Market Size to Hit USD 9.27 Bn by 2033. June 20, 2024. https://www.biospace.com/direct-to-consumer-laboratory-testing-market-size-to-hit-usd-9-27-bn-by-2033
- TB Duque et al. Direct-to-Consumer Testing (DTC): Destined to Connect or Disrupt. Buyer Be Aware (An Infectious Disease Perspective). Clin Microbiol Newsl. 2022;44(4):33–40. doi:10.1016/j.clinmicnews.2022.02.001.
- S Tandy-Connor et al. False-positive results released by direct-to-consumer genetic tests highlight the importance of clinical confirmation testing for appropriate patient care. Genet Med. 2018;20(12):1515–1521. doi:10.1038/gim.2018.38.
- MN Weedon et al. Use of SNP chips to detect rare pathogenic variants: retrospective, population based diagnostic evaluation. BMJ. 2021; 372:n214. doi:10.1136/bmj.n214.
- S Jean et al. At-Home Testing for Infectious Diseases: The Laboratory Where You Live. Clin Chem. 2021;68(1)19–26. doi:10.1093/clinchem/hvab198.
- ZK Siddiqui et al. Implementation and Accuracy of BinaxNOW Rapid Antigen COVID-19 Test in Asymptomatic and Symptomatic Populations in a High-Volume Self-Referred Testing Site. Microbiol Spectr. 2021;9(3): e0100821. doi:10.1128/Spectrum.01008-21.
- NC Okoye et al. Performance Characteristics of BinaxNOW COVID-19 Antigen Card for Screening Asymptomatic Individuals in a University Setting. J Clin Microbiol. 2021;59(4);e03282-20. doi:10.1128/JCM.03282-20.
- ADLM. Direct-to-consumer laboratory testing. October 30, 2024. https://myadlm.org/advocacy-and-outreach/position-statements/2024/direct-to-consumer-laboratory-testing#:~:text=ADLM%20position&text=Only%20reputable%20CLIA%2Dcertified%20laboratories,them%20in%20interpreting%20the%20results.
- G Adedokun et al. Sample preparation and detection methods in point-of-care devices towards future at-home testing. Lab Chip. 2024;24(15):3626–3650. doi:10.1039/d3lc00943b.
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