High levels of a compound called C-reactive protein may be a sign of a future risk for heart attacks, stroke and cancer, though it does not seem to be a cause, researchers said on Tuesday.
An analysis published in the journal Lancet attempts to resolve a long-standing debate over C-reactive protein, or CRP -- whether it is a warning sign of heart trouble, or a direct cause.
Some studies have suggested the protein, which is associated with inflammation, may be as important as high cholesterol in causing heart disease.
A team led by John Danesh at Britain's University of Cambridge and 269 other scientists pooled data from 54 long-term studies of more than 160,000 people in 18 countries.
They showed that CRP is linked with the future risk of heart attacks, stroke, deaths from various cancers, chronic lung disease, injuries and other conditions.
But most of the findings linking CRP to heart disease were explained by other, already known risk factors, such as smoking, blood pressure, obesity and high cholesterol.
They said the findings reduce the likelihood that CRP is a cause of heart disease.
Dr. S. Matthijs Boekholdt of the Academic Medical Center in Amsterdam, Netherlands, said in a commentary he did not think the study resolved the question of whether CRP leads to a higher risk of heart disease or is merely a sign of it.
But he added that the study suggests CRP may still be useful as a way to see if other drugs, such as statins, are lowering such risks.
A major study last year called Jupiter showed that giving AstraZeneca's cholesterol fighter Crestor, or rosuvastatin, cut deaths, heart attacks and strokes in middle-aged people with healthy cholesterol levels but elevated levels of C-reactive protein.
Even if CRP turns out to be not directly causal in cardiovascular disease, it might be useful to identify individuals at cardiovascular risk and to quantify the efficacy of our interventions, Boekholdt wrote.