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Methodological issues facing studies of atherosclerotic change
J L Probstfield1, R P Byington, D A Egan
1Clinical Trials Branch, National Heart, Lung, and Blood Institute, Bethesda, MD 20892.
Insights
B-mode ultrasonography offers a cost-effective method for evaluating atherosclerosis progression. Further research is needed to refine its use in assessing intimal-medial thickness and clinical events.
Area of Science:
- Cardiovascular Medicine
- Medical Imaging
- Biomedical Engineering
Background:
- Coronary heart disease is linked to coronary artery lesions, prompting research into interventions for atherosclerotic change.
- B-mode ultrasound of peripheral arteries is currently the most accurate method for evaluating atherosclerotic disease extent.
Purpose of the Study:
- To strengthen the rationale for using B-mode ultrasonography in assessing atherosclerosis natural history.
- To address key methodological issues for improved clinical application.
Main Methods:
- Evaluating primary endpoints using composite/individual measurements of carotid artery atherosclerosis.
- Assessing new methodologies for lesion anatomy and rupture potential.
- Developing complementary methods using angiography and ultrasound wall assessment.
Main Results:
- Consistent methodology is crucial for valid, precise, and reliable measurements of atherosclerotic change.
- Multiple measurements and data reduction techniques can enhance comparisons.
- Identifying covariates and confounding interventions requires monitoring biochemical, physiological, and clinical variables.
Conclusions:
- B-mode ultrasonography offers cost/benefit advantages for continuous variable assessment (intimal-medial thickness).
- Demonstrating a direct link between intimal-medial thickness and clinical events is essential.
- Methodology for ultrasound assessment of atherosclerosis continues to evolve.
Background:
The association between coronary heart disease and lesions of the coronary arteries has led to investigations of different interventions on atherosclerotic change. Currently, B-mode ultrasound of the peripheral arterial vessels, rather than arteriography of the coronary arteries, provides the most accurate evaluation of atherosclerotic disease extent in the patient.
Methods And Results:
When measuring the effect of risk factor modification on atherosclerotic change, it is important to select appropriate methods and end points for quantifying disease and evaluating subsequent change. Measurements must be valid, precise, and reliable and require appropriate a priori definitions of end points and their change. Consistent methodology within studies is crucial. Multiple measurements and data reduction methods can increase the efficiency of comparisons and merit careful consideration. Missing data arising from nonvisualization of sites complicate analyses. Identifying both covariates of atherosclerotic change and possible confounding interventions require monitoring biochemical, physiological, and/or clinical variables and making inferences from these.
Conclusions:
To strengthen the rationale for use of B-mode ultrasonography in assessing the natural history of atherosclerosis, four methodological issues must be addressed: evaluation of primary end points using composite and/or individual measurements of atherosclerotic assessment from the carotid arteries, evaluation of new methodology that may allow assessment of the anatomy of specific lesions and/or their potential for rupture, development of methods making complementary use of both angiographic measurements of lumen diameter and ultrasound assessment of the arterial wall, and concrete demonstration of a direct link between increasing intimal-medial thickness and subsequent clinical events. The use of a continuous variable (intimal-medial thickness) in ultrasound studies offers cost/benefit advantages; this methodology continues to evolve.