USPSTF: Nontraditional risk factors inadequate to assess CVD risk

Evidence has not sufficiently shown the benefits and harms of adding high-sensitivity C-reactive protein, ankle-brachial index and coronary artery calcification score to assess CVD risk in patients who are asymptomatic, according to a draft recommendation statement released by the U.S. Preventive Services Task Force.

“The previous recommendation [from 2009] considered the evidence on several risk factors in addition to the [Framingham risk score],” the task force wrote. “The major change in the current recommendation is that the [Pooled Cohort Equation] was used in addition to the [Framingham risk score], and the recommendation focused on only three nontraditional risk factors” — high-sensitivity CRP, ankle-brachial index and CAC score.

Improving risk assessment

Adding more risk factors can improve CVD risk assessment models and targeted therapies. High-sensitivity CRP, ankle-brachial index and CAC score have been shown through adequate evidence to improve discrimination, calibration and reclassification, which led to the USPSTF to further review their place in screening for CVD.

Evidence on the reduction of CVD events and mortality have been inadequate regarding treatment decisions based on existing assessment models with high-sensitivity CRP, ankle-brachial index and CAC. There is adequate evidence on the small harms associated with early detection and intervention using these nontraditional risk factors, which include incidental findings, abnormal results and anxiety.

Clinicians should use the Pooled Cohort Equation when assessing CVD risk and guiding risk-based therapy in asymptomatic patients until evidence shows the benefit of adding more CVD risk factors, the task force wrote.

Although assessing risk with ankle-brachial index and high-sensitivity CRP is noninvasive and causes little direct harm, incidental findings and further testing from abnormal results can lead to additional expenses and potential adverse effects, the task force wrote.

The Reynolds risk score is the only risk assessment model in the U.S. that incorporates high-sensitivity CRP. Numerous guidelines recommend considering ankle-brachial index, high-sensitivity CRP or CAC score if risk assessment is borderline or unclear with traditional models.

Identifying patients at high risk for CVD events can benefit from intense risk factor management, whereas identifying low-risk patients can reduce the number of interventions, the task force wrote. Models and calculators including the Framingham risk score and Pooled Cohort Equation are used to quantify a patient’s 10-year CVD risk, although both models have been shown to underestimate and overestimate risk in some patients. Adding nontraditional risk factors to these models can potentially improve risk prediction, according to the task force.

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Treating asymptomatic patients

Various treatment options are utilized in asymptomatic patients, including cholesterol-lowering medications, a combination of diet and exercise modifications, BP management, aspirin and smoking cessation.

Research gaps remain in the utilization of nontraditional risk factors when assessing CVD risk. Future studies need to measure the effects of adding these risk factors to Pooled Cohort Equation on patient outcomes and clinical decision thresholds, especially in more diverse populations, the task force wrote.

“While there is some evidence that [ankle-brachial index], CAC and hsCRP can slightly improve clinicians’ ability to define risk, the amount of improvement is not large or precise enough to help clinicians make better treatment or care decisions to prevent heart attack or stroke,” Seth Landefeld, MD, chair of the department of medicine and the Spencer chair in medical science leadership at University of Alabama at Birmingham School of Medicine; member of the board of directors of the American Board of Internal Medicine, University of Alabama at Birmingham and University of Alabama Health Services Foundation, and a task force member, said in a USPSTF bulletin. “More research is needed to understand the benefits and harms of using these three nontraditional risk factors in addition to the traditional risk factors for assessing CVD risk.”

The USPSTF’s draft recommendation statements can be viewed on the task force’s website: www.uspreventiveservicestaskforce.org. Comments will be accepted until Feb. 12. Subsequently, the task force will decide whether to incorporate any comments and will issue a final recommendation. – by Darlene Dobkowski

Disclosure: Landefeld is a member of the USPSTF.