A test that measures the level of procalcitonin in the blood has been cleared for expanded use by the U.S. Food and Drug Administration (FDA). When used in conjunction with other clinical information, the test may help healthcare practitioners avoid unnecessary antibiotic treatment without risking patients' safety.
Procalcitonin is a substance produced by many types of cells, often in response to bacterial infections but also in response to tissue injury. The level of procalcitonin in the blood can increase significantly in severe bacterial infections and in sepsis, the body's serious, overwhelming, and sometimes life-threatening systemic inflammatory response to a bacterial infection. As infections resolve, blood procalcitonin levels typically return to normal.
The FDA had first cleared the procalcitonin test to help determine the risk of a seriously ill patient developing sepsis or risk of progressing to severe sepsis and septic shock, which can be fatal. Last year, the test received another approval for use in helping to determine the risk of a patient with severe sepsis dying. This is based on not seeing the procalcitonin level decline significantly during the first few days after the diagnosis of severe sepsis is made. Now, the test may be used to help decide whether antibiotics can be discontinued in patients with sepsis and for helping to decide whether antibiotics should be started or stopped for patients with lower respiratory tract infections.
Treatment for sepsis often begins in the hospital emergency room and is continued and monitored with the person in an intensive care unit (ICU). Antibiotics are usually given through a vein (intravenously, IV) to treat the bacterial infection. Healthcare practitioners can monitor procalcitonin blood levels over time and when levels drop sufficiently, antibiotics may be safely discontinued. This can help reduce the use of antibiotics (some of which are very costly), the patient's exposure to antibiotics (some of which have significant side effects), and the time that patients stay in the ICU.
With the new clearance, the procalcitonin test may also be used to help guide treatment for lower respiratory infections, such as acute bronchitis, pneumonia, and acute forms of chronic obstructive pulmonary disease (COPD). The major causes of these infections are viruses rather than bacteria, and treatment with antibiotics is not effective.
Many patients with these infections are treated with antibiotics because both bacterial and viral respiratory tract infections have similar signs and symptoms and are difficult to distinguish without testing. This unnecessary use of antibiotics can increase medical costs and can lead to more drug-resistant bacteria. The procalcitonin test can help healthcare practitioners make decisions about antibiotic treatment because high levels are much more likely to be seen in bacterial, rather than viral, infections. This can help reduce the unnecessary use of antibiotics.
"Unnecessary antibiotic use may contribute to the rise in antibiotic-resistant infections. This test may help clinicians make antibiotic treatment decisions," said Alberto Gutierrez, Ph.D., director of the Office of In Vitro Diagnostics and Radiological Health at the FDA's Center for Devices and Radiological Health, in an FDA press release.
According to the FDA, the decision to clear the test for expanded use was based on results from research that compared standard antibiotic treatment to treatment guided by results from procalcitonin tests. Almost all of these studies showed comparable results in both groups. The patients whose treatment was guided by procalcitonin levels fared just as well as those who received standard treatment.
The FDA cautions that results from the test cannot be used alone for making treatment decisions. The test cannot determine the specific cause of a patient's symptoms, and conditions besides infections can increase blood procalcitonin levels. Healthcare practitioners should consider procalcitonin results along with other indicators of the patient's health status, as well as other laboratory tests.