As the National Institutes of Health tell it, biomarkers are objective indications of medical signs outside the patient that can be measured. Studies have shown that a biomarker known as procalcitonin (PCT) has been promising to evaluate risk of bacterial infections, such as sepsis.

PCT is known as a precursor to a hormone calcitonin, usually produced by the thyroid gland.  After a few hours of a severe bacterial infection, for instance, immune cells produce PCT. But the PCT shows increases with bacterial infections, not in viruses, DoveMed said. In that way, PCT is “useful is differentiating bacteria from other infectious agents,” according to DoveMed. That ability for measuring PCT makes it different and can be seen as a key biomarker.

As for sepsis, it is a serious and sometimes deadly illness caused by an overwhelming immune response to a bacterial infection, which can have many different underlying causes, according to the Centers for Disease Control and Prevention.

The death last year of Academy-Award winning actress Patty Duke from sepsis from a ruptured intestine raised awareness of the illness.

Still, a lack of a ‘gold standard’ diagnostic test for sepsis has resulted in diagnostic dilemmas, which may delay appropriate treatment and lead to poor outcomes, according to Robert A. Balk, MD, director of the division of pulmonary and critical care medicine at Rush Medical College, Chicago and his colleagues. More than $20 billion was spent on sepsis care in 2011, making it the most expensive condition managed in U.S. hospitals, they said.

“Because there is no confirmatory diagnostic test, the diagnosis of sepsis is based on clinical judgment of suspected infection,” the CDC says. A reliable sepsis surveillance definition based on objective clinical data is needed to more accurately track national sepsis trends and enable ongoing assessment of the impact of efforts to increase sepsis awareness and prevention.”

The CDC acknowledges the data challenges involving sepsis, but still found staggering numbers of people who died as a result of the illness. From 1999 to 2014, the CDC found a total of 2.4 million people whose deaths had sepsis linked among the causes. That was 6 percent of all deaths, the CDC said.

Sepsis In the ICU

Balk and his team studied the impact of procalcitonin in hospitals related to sepsis and found interesting results: testing on the first day of Intensive Care Unit (ICU)  admission for adult patients with sepsis is associated with reduced length of stay, less antibiotic exposure, and reduced hospital and pharmacy costs, according to Balk. They reported their findings in CHEST. 2017;151[1]:23-33). The researchers analyzed data on more than 15 million patients in the Premier Research Database; of those, more than 730,000 had a potential diagnosis of sepsis, systemic inflammatory response syndrome (SIRS), septicemia, or a shock-related diagnosis on ICU admission or discharge, according to my report in  Frontline Medical News

After propensity matching to reduce potential bias, a total of 33,569 patients who had received PCT testing on ICU day 1 were identified; a control group of 98,543 non-PCT tested patients were identified as well, Frontline Medical News reported. Hospital costs were $2,759 lower for PCT-tested patients ($30,454 vs. $33,213), ICU costs were $1,310 lower ($20,155 vs. $21,465), and pharmacy costs were $331 lower ($4,238 vs. $4,568). PCT-tested patients also were more commonly discharged to home (44.1% vs. 41.3%), the researchers said.

The PCT-tested patients had less total antibiotic exposure, (16.2 days vs. 16.9 days) but higher laboratory costs, according to  Balk and his colleagues. Laboratory costs of the PCT-tested patients were $81 greater ($1,807 vs. $1,726), according to the report.

While PCT testing is cleared by the Food and Drug Administration to assist in identifying patients who are highly likely to develop sepsis, there is no approved sepsis test, Dr. Balk and his colleagues noted.

“This study is important in the validation of the ability of PCT testing to favorably impact the outcome of critically ill patients when used according to the FDA cleared guidelines,” the investigators said. “The cost savings were real and consequential, exceeding the potential increased costs of laboratory testing associated with PCT testing on ICU admission.”

Despite its emergence as a diagnostic criteria tool for sepsis in the 2012 Surviving Sepsis Guidelines, PCT testing has not been uniformly adopted, in part, because of cost considerations, Balk and his colleagues said in the Frontline Medical News story  To date, they said, there is no approved sepsis test that identifies a sepsis patient with a sufficiently high likelihood to make it clinically useful, according to Balk and colleagues.