Identifying Good Marker For Heart Risks
Since about half of all heart attacks occur without any warning, there is increasing interest in finding new ways to identify a person’s risk for heart attack.
A new statement, published in Circulation: Journal of the American Heart Association, offers guidance on how these new risk markers should be evaluated before being put into practice. The statement says an adequate evaluation of a new risk marker requires:
* a sound research design
* a representative at-risk population (this helps determine who might benefit from testing for the new marker), and
* an adequate number of outcome events (it’s tested in enough people to determine if the marker is truly linked to cardiovascular events, or if the relationship is just due to chance).
In addition, studies of a new marker should report what the marker adds to current risk prediction.
“If a marker has no added value beyond what we can predict based on traditional risk factors – such as cholesterol levels, weight and lifestyle factors – there’s no reason to track or measure it,” said Mark A. Hlatky, head of the statement writing group and professor of health research and policy and professor of medicine at Stanford University School of Medicine in Stanford, Calif.
Hlatky adds that several statistical measures are needed to assess the amount of additional information conveyed by a new marker, and that the clinical value of a marker should be assessed by its effect on patient management and outcomes.
The phases of evaluating a new risk marker include:
1. Proof of concept – Do new marker levels differ between subjects with and without outcome?
2. Prospective validation – Does the new marker predict development of future outcomes in a prospective cohort or nested case-cohort/case-cohort study?
3. Incremental value – Does the new marker add predictive information to established, standard risk markers?
4. Clinical utility – Does the new marker change predicted risk enough to change recommended therapy?
5. Clinical outcomes – Does use of the new marker improve clinical outcomes, especially when tested in a randomized clinical trial?
6. Cost-effectiveness – Does use of the marker improve clinical outcomes enough to justify the additional costs of testing and treatment?
“We believe that an organized approach to the development and critical appraisal of new risk markers will contribute to the improved clinical management of patients at risk of cardiovascular disease,” Hlatky said. “These criteria will be particularly important to the peer review process of research reports about novel risk markers, as medical journals can apply these criteria prior to publication of articles about new markers. These criteria should also be helpful in the development of clinical guidelines for the evaluation and management of patients at risk of developing a cardiovascular event.”