Blood test could help predict risk of death in two years: study

A blood test to detect higher levels of a heart protein, called troponin, could help predict the risk of death from any cause in the next few years, claims a large UK study.

Doctors look for high levels of troponin to diagnose a heart attack, but people often also have high levels of this protein without heart attack signs or symptoms, and it has been unclear what this indicated.

The researchers from the University of Southampton, UK, tested the troponin levels of 20,000 people and found that people with higher levels of this protein were nearly four times as likely to die in the next two or so years, compared to people with normal levels. The authors say this suggests that this protein may have a more general role as a marker of medium-term prognosis outside of just heart attack. The average age of people involved in the study was 61 and over half (53%) were women.

Nearly half (9345; 47%) were outpatients, nearly a quarter (4947; 25%) were inpatients and 28.5% (5708) were emergency care patients. More than 90% of them (18,282) had no clinical indication for cardiac troponin testing. In the remaining 9% (1718), doctors requested the test for clinical reasons.

Cardiac troponin was high in 1085 (just under 5.5%) patients. Some 1782 (9%) patients died after a year and a total of 2825 (14%) had died just over two years (809 days) later. Patients were nearly four times as likely to die if their cardiac troponin test result was high (45%) as those whose test results fell within the normal range (12%).

Further analysis accounting for age, sex, hospital location and kidney function revealed that an abnormally high cardiac troponin level was independently associated with a 76% heightened risk of death, not only from both cardiovascular disease, but also other causes.

In fact, the most common cause of death was cancer (1308; 46%), followed by cardiovascular disease (363; 13%).

After excluding deaths that occurred within 30 days, a parameter used 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. This indicates that this association wasn’t driven purely by a short-term risk of death, the researchers highlighted.

The researchers acknowledged that it is an observational study with several limitations, and as such, no firm conclusions about cause and effect can be drawn. Limitations include the fact that the study was carried out at one hospital and that potentially influential factors, such as personal background information and concurrent conditions, weren’t known.

“This study suggests that [cardiac troponin] may have a more general role as a marker of medium-term prognosis outside [heart attack],” they concluded.

“Further research is required to confirm these findings across multiple settings and to evaluate whether any intervention can adjust the increased risk demonstrated,” they said.

Image caption: iStockphoto.com/kasia2003