Please see the page Advice on the proper use of devices for general guidance.
1. What is a self-test?
Self-tests or self-diagnostic devices are in vitro diagnostic medical devices (IVDs) intended for use by non-professional users (lay persons). With a self-test, the lay person generally carries out all the operations (from sampling to interpretation of the result), without the help of a healthcare professional.
These tests are made to be used easily and safely, with minimal risk of error.
Self-tests can use different sources of body samples, such as blood, urine or saliva. They are used in various situations to detect or provide information on:
- a disease (e.g. HIV, COVID-19, flu, etc.);
- a physiological condition (e.g. pregnancy test, ovulation test, etc.);
- a predisposition (e.g. lactose or gluten intolerance test, genetic predisposition to breast cancer, etc.);
- …
Self-tests are available in several forms, i.e. cassettes, strips, sticks, etc.
2. How can I check whether my self-test is compliant?
Self-tests must have a CE marking followed by four digits. These digits identify the notified body that verified the compliance.
The CE marking must appear on the device and/or the packaging, as well as in the instructions for use.
Self-tests which are CE marked can be sold in the EU Member States. However, in Belgium, the information provided with a medical device intended for lay persons (instructions for use, labelling) must be provided at least in the three official languages (i.e. French, Dutch and German). This information can also be made available in the form of internationally recognised symbols. If other symbols are used, they shall be defined in the instructions for use.
3. How do I use my self-test correctly?
- Check if your self-test is CE marked (see Question 2). The packaging must also specify that the test is intended for self-testing, using words such as ‘self-diagnosis’, ‘self-test’, etc. or by means of a symbol.
- Carefully read the instructions for use before using the self-test.
- Check the expiry date of your self-test.
- Respect the storage conditions (e.g. refrigerator, freezer, etc.) to avoid compromising the test.
- Check the intended purpose/indication of your self-test (e.g. children or adults, patients with reduced immunity, individuals with or without symptoms of the suspected disease, etc.).
- Check potential interference for your self-test: several factors can impact the results of your self-test (e.g. age, gender, menstruation, infections, exercise, fasting, diets or medication).
- Make sure you understand the various steps and have the necessary equipment to use your self-test. Feel free to ask a healthcare professional for help if your self-test seems complicated to use.
- Follow the steps carefully and observe the environmental conditions (e.g. temperature, surface, hygiene, etc.) to avoid false results.
- Respect the waiting time before reading the result (if applicable). If you read the result too early or too late, the result may be incorrect.
- Interpret the results using the instructions for use (if applicable). The result displayed (positive/negative/invalid) varies from one self-test to another. It can be linked to the presence of a line, a specific colour, a symbol, or even the control intensity.
- Once you know the result of your self-test, you will find all the steps to take in the instructions for use in the event of a positive, negative or invalid result. In case of a positive result or if in doubt (e.g. presence of symptoms), please make an appointment with a healthcare professional to confirm the result of the self-test.
Do not take any medical decision after a self-test without consulting a healthcare professional. If you use a self-test to monitor an already diagnosed disease, please do not adapt your treatment without the agreement of a healthcare professional.
4. Can a self-test give false positive or false negative results?
Yes, it is possible.
In the instructions for use, the manufacturer provides the user with information regarding the sensitivity and specificity of the self-test.
(Diagnostic) sensitivity is the ability of a test to give a positive result in the presence of a marker associated with a disease, a physiological condition or a predisposition.
This sensitivity is expressed as a percentage. A test with 99 % sensitivity identifies 99 positive people (true positives) out of 100 people who are truly positive. This means that one positive person will not be detected by the test (false negative). For example, a pregnancy test with 98 % sensitivity will not detect pregnancy in two out of 100 pregnant women. The greater the sensitivity, the lower the risk of a false-negative result.
This diagnostic sensitivity should not be confused with analytical sensitivity, which is sometimes mentioned in instructions for use. Analytical sensitivity stands for the detection limit of a marker. It is often expressed with a detection threshold (e.g. ‘this test detects the presence of this hormone from 200mUI/mL of urine’).
(Diagnostic) specificity is the ability of a test to correctly detect the absence of a marker associated with a disease, a physiological condition or a predisposition.
This sensitivity is expressed as a percentage. A test with 99 % specificity identifies 99 healthy people (true negatives) out of 100 who do not have the marker. Nevertheless, one healthy person will be detected as positive by the test (false positive). For example, a pregnancy test with 96 % specificity will give a positive pregnancy result for four women out of 100, even though they are not pregnant. The greater the specificity, the lower the chance of a false-positive result.
Some instructions for use address the reliability of the test, but actually there is no specific definition of reliability. It encompasses several concepts, including sensitivity, specificity, accuracy, repeatability, etc.
You may obtain false negatives or false positives for several reasons: non-compliance with storage instructions, omission of a test step, too long waiting time, interference with the health condition, etc.
5. Is the result of my self-test as reliable as the one obtained with a test intended for use by a health professional?
In general, a test performed by a healthcare professional is more reliable. In fact, the lay person is likely to make more mistakes when performing the self-test. Moreover, some tests intended for healthcare professionals are more reliable as they use more suitable samples.
If you have any doubts about your self-test result, please consult your healthcare professional.
5. Where can I buy a self-test?
Self-tests are available over the counter. This means they can be sold in pharmacies, supermarkets, stores and on the internet. However, always make sure that the self-test is compliant and intended for the Belgian market (see Question 2). The reliability of the self-test you use is the same, no matter where you bought it. Nevertheless, the pharmacist can provide more explanations and clear information on how to use the self-test.