SOUTHAMPTON, United Kingdom — Could a single protein in the body mean the difference between life and death? New findings out of the United Kingdom suggest that high levels of troponin, a protein usually used to exclude the possibility of a heart attack in patients with chest pain, may indicate a heightened risk of death from any cause over the next couple of years. Researchers warn this is the case even when there is no known or suspected evidence of cardiovascular disease.
All in all, these findings have led the research team to conclude troponin may hold a role as a more general indicator of medium term survival. High cardiac troponin levels are often seen among hospital patients who don’t show specific signs of a heart attack, but the clinical significance of this has never been clear, researchers add.
So, in an attempt to explore this topic further, they tracked the survival of 20,000 hospital patients who took a troponin blood test for any reason between June and August 2017 at a large teaching hospital – regardless of the original, specific clinical indication. The average age of these patients 61 and over half (53%) were women.
Meanwhile, close to half (9,345; 47%) were outpatients, nearly a quarter (4,947; 25%) were inpatients, and 28.5 percent (5,708) were emergency room patients. Also, over 90 percent (18,282) had no clinical indication for cardiac troponin testing. For the remaining nine percent (1,718), however, doctors requested the test for clinical reasons.
Cardiac troponin levels came in very high among 1,085 patients (just under 5.5%), and 1,782 (9%) died during the following year. Also, a total of 2,825 (14%) passed away just over two years (809 days) later. Patients were found to be up to nearly four times as likely to die if their cardiac troponin test score was as high (45%) as others whose test results fell within the normal range (12%).
When the researchers conducted further work that accounted for age, sex, hospital location, and kidney function, they discovered that an abnormally high cardiac troponin level was independently associated with a 76-percent heightened risk of death — and not just from purely cardiovascular disease either. The study finds that others causes were linked as well.
In fact, the most common cause of death was cancer (1,308; 46%), followed by cardiovascular disease (363; 13%).
Researchers were sure to exclude any deaths that occurred within 30 days, which was a parameter chosen to define the likelihood that this was associated with the reason for their hospital stay, the link between cardiac troponin and heightened risk of death persisted. All of this suggests, researchers explain, that the observed association wasn’t driven purely by a short term risk of death.
To be clear this work was an observational study. As such, it can not definitively form any firm conclusions regarding cause and effect. Beyond that, study authors also acknowledge a number of limitations. To start, the study was carried out at one hospital – meaning potentially influential factors, such as personal background information and concurrent conditions, weren’t known.
Moreover, it seems biologically implausible on the surface that cardiac troponin level itself would pose such a major death risk. In all likelihood, it is more likely that it represents a broad spectrum of health issues, including those that haven’t been diagnosed yet, which increases the risk.
“This study suggests that [cardiac troponin] may have a more general role as a marker of medium-term prognosis outside [heart attack],” study authors conclude in a media release. “Further research is required to confirm these findings across multiple settings and to evaluate whether any intervention can adjust the increased risk demonstrated.”
The study is published in the journal Heart.