August 19th, 2011
Is Coronary Calcium Better Than CRP for Predicting CV Events?
A new study suggests that people with low LDL levels and high CRP levels may benefit from coronary artery calcium (CAC) scans to identify those who are most likely to benefit from statin therapy. In a paper published in the Lancet, Michael Blaha and colleagues analyzed data from 950 people enrolled in the Multi-Ethnic Study of Atherosclerosis (MESA) who met the entry criteria for the JUPITER study.
After 5.8 years of of follow-up:
• 47% of the subjects had a calcium score of zero. CHD event rates in this group were 0.8 per 1000 person-years. They calculated that in this group 124 patients would need to be treated with rosuvastatin to reduce one cardiovascular event (NNT = 124). Overall, 6% of coronary events and 17% of cardiovascular events occurred in this group.
• 28% of the subjects had a CAC between 1 and 100. In this group the cardiovascular NNT was 54.
• 25% of the subjects had CAC scores over 100. This group accounted for 74% of all coronary events. The CHD event rate was 20.2 per 1000 person-years, and the cardiovascular NNT was 19.
The investigators also report that unlike CAC scores, CRP levels did not predict outcome in this population of patients who already had CRP levels ≥2 mg/L.
The investigators concluded:
CAC seems to further stratify risk in patients who meet eligibility criteria for JUPITER, and might be used to target a subgroup of patients expected to derive the most and the least absolute benefit from treatment. Focusing of treatment on the subset of individuals with low LDL cholesterol with measurable atherosclerosis might represent a more appropriate allocation of resources, reduce overall health-care cost, and prevent the occurrence of a similar number of events.
In an accompanying comment, Axel Schmermund and Thomas Voigtländer write that “although definitive proof of treatment effects is scarce, CAC identifies high cardiovascular risk, and statin therapy is most effective in high-risk patients. In our practice, we therefore focus on CAC… for expanded risk stratification in asymptomatic patients.”
To join the panel discussion about this study, click here.