Emerging risk factors for coronary heart disease: a summary of systematic reviews conducted for the U.S. Preventive Services Task Force.
BACKGROUND
Traditional risk factors do not explain all of the risk for incident coronary heart disease (CHD) events. Various new or emerging risk factors have the potential to improve global risk assessment for CHD.


OBJECTIVE
To summarize the results of 9 systematic reviews of novel risk factors to help the U.S. Preventive Services Task Force (USPSTF) evaluate the factors' clinical usefulness.


METHODS
Results from a MEDLINE search for English-language articles published from 1966 to September 2008, using the Medical Subject Heading terms cohort studies and cardiovascular diseases in combination with terms for each risk factor.


METHODS
Studies were included if the participants had no baseline cardiovascular disease and the investigators adjusted for at least 6 Framingham risk factors.


METHODS
Study quality was evaluated by using USPSTF criteria and overall quality of evidence for each risk factor by using a modified version of the Grading of Recommendations, Assessment, Development, and Evaluation framework. Each factor's potential clinical value was evaluated by using a set of criteria that emphasized the importance of the effect of that factor on the reclassification of intermediate-risk persons.


RESULTS
9 systematic reviews were conducted. C-reactive protein (CRP) was the best candidate for use in screening and the most rigorously studied, but evidence that changes in CRP level lead to primary prevention of CHD events is inconclusive. The other evaluated risk factors were coronary artery calcium score as measured by electron-beam computed tomography, lipoprotein(a) level, homocysteine level, leukocyte count, fasting blood glucose, periodontal disease, ankle-brachial index, and carotid intima-media thickness. The availability and validity of the evidence varied considerably across the risk factors in terms of aggregate quality, consistency of findings, and applicability to intermediate-risk persons in the general population. For most risk factors, no studies assessed their usefulness for reclassifying intermediate-risk persons.


CONCLUSIONS
Because of lack of access to original data, no firm conclusions could be drawn about differences in risk prediction among racial and ethnic groups. The review did not emphasize within-cohort comparisons of multiple risk factors.


CONCLUSIONS
The current evidence does not support the routine use of any of the 9 risk factors for further risk stratification of intermediate-risk persons.
Helfand
Mark
M
Oregon Evidence-based Practice Center, Veterans Affairs Medical Center, andOregon Health & Science University, Portland, Oregon 97239, USA.
Buckley
David I
DI
Freeman
Michele
M
Fu
Rongwei
R
Rogers
Kevin
K
Fleming
Craig
C
Humphrey
Linda L
LL
D055109:Ankle Brachial Index; D015415:Biomarkers / Q000097:blood; D002114:Calcinosis / Q000000981:diagnostic imaging; D002340:Carotid Artery Diseases / Q000150:complications; D003327:Coronary Disease / Q000175:diagnosis* / Q000517:prevention & control*; D003331:Coronary Vessels / Q000473:pathology; D006801:Humans; D010510:Periodontal Diseases / Q000150:complications; D011859:Radiography; D018570:Risk Assessment; D012307:Risk Factors
D015415:Biomarkers