News
Should your patient self-test?
Friday 18th November 2022
Dr John Rees
Although self-test kits can provide information about a patient's health, a test result by itself is not a diagnosis. Responsible self-test manufacturers should tell their customers that if they are concerned about their symptoms to speak with their doctor or pharmacist - and not buy a test kit.
Medical tests are usually only requested by doctors after first taking into account their patient's symptoms and clinical history, rather than testing first, and then working out how this relates to symptoms. Doctors are rightly concerned that the wide-spread use of self-testing kits could increase the burden on already overstretched NHS services. Although currently, there is no evidence that this is happening. Similar concerns were expressed by doctors almost 50 years ago, when home pregnancy tests were first made available.
Self-testing changed the way patients have managed their diabetes, and women have become empowered by the availability of pregnancy and ovulation tests. Similarly, screening tests for bowel and prostate cancer have the potential to provide valuable information about a patient's health, providing the limitations of the tests are clearly explained to the patient prior to testing.
Most blood tests currently used in NHS hospital laboratories have not required any external review or validation except for a declaration by the manufacturer that the tests comply with the regulations. This is in contrast to the regulations for self-test kits which requires independent review of the technical files, and manufacturing site visits, before they can be approved for sale. Manufacturers must present evidence to Notified Bodies showing the technical performance of the test, as well as user trials with laypersons to show that most ordinary people can use the test and interpret their result correctly. The packaging and information provided with the self-test kit is also reviewed with regards to the claims made, and any proposed changes to this information, except for the most minor changes, need to be referred back to the Notified Body for approval. The regulations are changing in the UK, and in the coming years will require hospital laboratory tests to be scrutinised to the same level as self-testing kits.
Self-test kits detect the same biomarkers as tests used hospital labs but have been designed to be reliable, safe and easy to use by anyone at home. Nevertheless, all medical tests, whether performed by a hospital lab, or at home with a self-test kit, will give some false positive and false negative results. This is because no biomarker is 100% reliable for a specific disease.
For some biomarkers, the number of false positive or negative results can be relatively high, so it is important that patients are aware of the consequences that a test result may have before deciding to self test. All medical tests will give some people false positive or false negative results which could lead to unnecessary further investigations and treatment, or risk a missed diagnosis. Clear communication of the implications of a test result is an area where manufacturers and retailers of self-tests should aim to address in their promotional materials.
Rigorous, unbiased research is needed to identify the positive or negative impact of self-testing on patient outcomes and NHS resources, rather than research based on opinions, anecdotes and social media polls. Without evidence based research, we should be careful not to demonise innovations in health technology, or demotivate the research scientists that are developing their ideas and innovations for future medical diagnostics.