Point-of-care testing refers to diagnostic tests that take place outside of a laboratory. Many of these can be performed by the patient or by an office-based physician. However, the specificity and sensitivity of point-of-care testing is subpar compared with laboratory diagnostics.
What is point-of-care testing?
Point-of-care testing is a medical term used to describe near-patient laboratory diagnostics. Many of these can be performed by the patient or by an office-based physician. Examples include pregnancy testing or blood glucose measurement. Point-of-care testing is the term used in medicine to describe patient-oriented laboratory diagnostics. This includes all diagnostic tests that are performed directly in the hospital, in the pharmacy or in the practice of a registered physician instead of in a central laboratory. In emergencies, point-of-care testing can even take place in the patient’s home. For some diagnostic tests of point-of-care testing, it is even considered to be performed by the patient. An example of this is pregnancy testing. The measurement of blood glucose, as diabetics regularly do, is also carried out by the patient independently. In some cases, the terms on-site test or rapid test are used synonymously with point-of-care testing. A completely uniform definition of the individual terms does not yet exist. Ultimately, therefore, the term point-of-care testing is also a rather open and fuzzy term to date.
Function, effect and goals
The most important characteristic of all types of point-of-care testing is the immediate proximity to the patient. That is, the performance and results of the methods take place outside the laboratory. The test material in these testing methods is usually either blood or urine. Sometimes saliva can also be used for examination. The samples do not need to be prepared further for these test methods, which greatly simplifies the procedure. The reagents used in the tests are ready to use and include single-use measuring devices. No medical expertise is required to perform these tests. This means that the patient can also perform the tests independently, usually following the package insert. The results of the examination are available quickly. A diagnostic conclusion can therefore be drawn from the immediately available results in the shortest possible time. Pregnancy tests are one of the best-known examples of point-of-care testing. The test substance in this diagnostic procedure is urine. As a rule, testing of the morning urine is recommended. The test strip of the rapid test measures the concentration of hCG. This is a pregnancy hormone. If this hormone is present in a certain concentration, the on-site test indicates a positive result. Meanwhile, there are different variants of the pregnancy test. Either the test strip turns a color indicated on the package insert when a certain concentration of the pregnancy hormone is present, indicating a positive result, or a display on the measuring device informs the user of the test result. Certain symbols may also appear to indicate a positive result. In contrast to pregnancy tests, the blood is the body fluid that is relevant to the test in the case of blood glucose measurements. The user pricks his finger with a lancing device. He inserts a test strip into the meter, which takes up the blood from the puncture wound and determines the sugar values from it. With point-of-care testing, the results are available immediately. Most tests in this field deliver a result after 15 minutes at the latest, whereas in the laboratory it can take half an eternity for the patient to receive results. Rapid availability is thus one of the greatest strengths of this methodical diagnostic procedure. The blood glucose measurement of diabetics, for example, must not take much time to be useful. The time advantage of rapid tests is also important in intensive care units, during anesthesia, or in dialysis, where quick decisions have to be made on the basis of test values.Here, rapid tests for certain pathogens or autoimmune diseases are primarily used, but coagulation values or kidney function values are also often determined in the aforementioned areas using rapid tests, which allow a quick response to any test results. In addition to waiting time, point-of-care testing eliminates just as much effort because the test strips and testing devices are designed to be user-friendly and highly automated.
Risks, side effects, and hazards
Risks, side effects, and hazards are generally not expected for the patient with point-of-care testing methods. Despite this advantage, point-of-care testing methods are not suitable for all concerns. For example, the sensitivity of the methods is significantly lower than that of laboratory techniques. That is, point-of-care testing methods are less sensitive and more likely to yield false results. Point-of-care testing for home use in particular often produces erroneous results, for example if the user does not follow the package insert. Also the specificity, i.e. the accuracy of the tests cannot be compared to the precision of other methods. The sample throughput of point-of-care testing is therefore much lower than that of laboratory methods. For these reasons, a pregnancy test, for example, is not sufficient for the undoubted diagnosis of pregnancy. Users are usually advised to seek additional clarification in a doctor’s office. Point-of-care testing also cannot detect every type of value. A comprehensive diagnosis is therefore not possible at all using these methods. If there were only point-of-care testing, the rate of misdiagnosis would be significantly higher than it is at present. Today, however, hospitals and office-based physicians coordinate their laboratory diagnostics and their rapid tests in such a way that the advantages of both methods complement each other harmoniously.
