Self-tests
Another big topic related to new IVD devices is the usage of self-tests (ST). There are several risks associated with them13:
Diagnostic sensitivity
False-negatives occur when the device shows a negative result, eventhough the true result should be positive. Since self-testers often perform tests for reassurance, without considering the disadvantages12, in the best case self-tests for high-severity conditions should be available only if the false-negative ratio is in the similar range as for clinical tests. Otherwise poorly informed patients may be harmed in case of false-negative results; treatment will be postponed and the condition will worsen. Consumer information should promote more informed usage for self-testing12.
False-positives occur when the device shows a positive result, though the true result should be negative. Although this incorrect result might be seen as less harmful, because a positive result for a severe disease like HIV must be then confirmed 3, a patient testing positive for a milder condition might receive unnecessary and potentially harmful treatment.
Analytical sensitivity
False-negative between infection and seroconversion (time period during which a specific antibody develops and becomes detectable in the blood): this risk is related to immunoassays and is less relevant for tests like ours which are based on the detection of nucleic acids.
Accuracy
Accuracy depends on the performance of the test and the ability of an inexperienced person to properly use it13. While the performance is a subject of regulation, it was shown that some devices fail to deliver clear complete usage instructions13. However, even when the instructions are provided, they are not always followed by all the users13. There are contradictory results regarding this aspect, for example a review about the studies on usage of HIV self-tests showed that most participants properly performed home tests and obtained accurate results3. The same review suggests people often had trouble performing blood-based tests. On the other hand, the results of another study among young adults suggests that many of them did not follow all instructions while performing the test for such severe conditions as a HIV infection4.
A poorly functioning home test may harm credibility in the reliability of rapid tests and, for example, weaken efforts to expand HIV detection2.
Absence of professional counseling
In case of self-testing the user does not get immediate counseling from a health professional, which means delayed access to professional care11. Currently available HIV self-tests have limited follow-up options, for example, in the U.S. generally only a phone number is provided which participants may call8. Instead, governmental programs of follow-up counseling with clear further instructions are required in case of a positive result. This study also points out that self-tests additionally fail to guide users, whose tests are negative, to preventive services in order to reduce the risk of future HIV infections8. As a possible solution, self-test devices may be equipped with an Internet of Things module reporting the case with delivery of timely, active follow-up counseling and referrals over the phone8.
Some users may initiate self-treatment based on results they found on the Internet, which may be misleading and harmful for their health.
Wrong interpretation of results by badly informed users may cause treatment interruption or changes in the dosage of prescribed medications.
Facing positive results for severe conditions
A positive result for a severe disease may have an effect on the emotional and psychological condition of the user. Before making self-tests for many diseases available to the general public, this effect must be studied more thoroughly.
Overall effect on public health
Not many studies have been conducted in this regard since there are few self-test devices for specific conditions available on the market. Thus, the effect of the ability to test yourself for everything is not known. Before the introduction of self-tests for HIV, a mathematical model in one study predicted an increase in HIV among men having sex with men in Seattle, even if home-use tests would increase overall testing6.
Another concern is not reaching the target group. Before the first HIV self-test was permitted in the U.S., some experts expected that this test would be mostly used by wealthy HIV-uninfected people, so that it would not fulfill its goal to help infected people to discover their condition2. Their study suggested that the test may have a perverse effect of false-positive and false-negative results. On the other hand, it was shown in another study that self-test usage in the Netherlands was higher among high-risk individuals7.
Probably not all the users who were tested positive for severe conditions would ask for professional medical counseling, even if it was available. Some diseases currently must be reported to epidemiology and infectious disease control centers to enable disease monitoring and epidemic prevention. If positive self-test results are not reported, epidemic may be overseen. However, this may be solved by an Internet of Things module8, but this might also limit the device's usage because of an increased price.
Coercion
Another concern regarding self-tests might be coercion11, since test usage could be enforced on risk groups. This may especially be the case for socially stigmatized conditions like HIV.
Counterfeit
Counterfeited self-tests, which are providing false results to users, may have a huge effect on individual and public health. Strict regulation of test market and informing potential users about trusted sources of tests are therefore crucial.
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