Purpose for new tests: The Search for a Solution
Researchers continually look for new ways to improve early detection and diagnosis of diseases, more accurately monitor conditions, and better predict outcomes (prognosis). The goals of improving and advancing patient care often provide the incentive for the development and use of new or improved laboratory tests.
One of the most common ways a new test gets developed is through the recognition of a need for an accurate test to diagnose or monitor a particular disease or condition. An example is the test for troponins. After years of looking for a better way to diagnose heart attacks or acute coronary syndrome (ACS), it was realized that the protein troponin is released into the bloodstream when heart muscle is damaged. Measurement of troponin levels in the blood has now gained acceptance in the medical community as a test for evaluating patients with chest pain to help determine if they have had a heart attack.
Often, researchers look to improve the way in which a condition is detected or a substance of interest is measured. Their goal is to improve upon the accuracy, precision, sensitivity and/or specificity of an existing test. (For more on these, see the article How Reliable is Laboratory Testing?: Key Concepts.) This can sometimes be accomplished by developing and employing a new way (methodology) of testing. An example is the development of a molecular method that detects genetic material, such as polymerase chain reaction or PCR, to detect infections as a replacement for an immunoassay method that may be less sensitive or specific. Sometimes the decision to use new tests for established analytes is based on whether a new method offers faster results, moving from a slower, more labor-intensive method to an automated method that generates many more patient results in a shorter amount of time.
In some cases, an existing test may evolve to have a new clinical use. A test may have been developed for one purpose, but over time, a new use for the test becomes apparent. This is how the high-sensitivity C-reactive protein (hs-CRP) test was added as a marker for predicting the risk of heart disease. The original purpose of the CRP test was to detect significantly increased levels to identify infection or inflammation associated with disease, but researchers found a new use: measuring it with highly sensitive tests that can detect slight increases within the "normal range" to help predict cardiovascular risk.
There are several questions that can be considered when evaluating the merits of developing a new test:
- Is the new test more accurate? That is, can it detect disease when it is present and rule it out when it is not present?
- Is it less invasive? Is the sample required easier to obtain and/or does the procedure cause less discomfort for the patient?
- Is the new test faster? Does it provide results more quickly so that treatment can begin sooner?