Will the Real Risk Factors Stand Up: A Surprise From Bogalusa

Linda Brookes, MSc;   Gerald S. Berenson, MD

Disclosures

February 13, 2012

In This Article

Background to the Interview

The Bogalusa Heart Study begun in 1972 as an epidemiology study of cardiovascular risk factors in children and adolescents living in Bogalusa, Louisiana, a biracial (African American/white) rural community located 70 miles north of New Orleans. The Study eventually evolved into long-term observations in young adults.[1,2] Originally funded as a Specialized Center of Research-Arteriosclerosis (SCOR-A) by the National Heart, Lung, and Blood Institute (NHLBI), it was part of a project to conduct research on atherosclerosis, coronary artery disease, hypertension, diabetes mellitus, and complications of cardiovascular-renal disease as the major causes of deaths in the United States. The Bogalusa Heart Study has produced many reports demonstrating that the major etiologies of adult heart disease begin in childhood. Early autopsy studies showed atherosclerotic lesions in the aorta and coronary vessels, and changes in the kidney vasculature related strongly to clinical cardiovascular risk factors, clearly indicating that atherosclerosis and hypertension begin in early life. These findings have been extended by noninvasive imaging studies of the heart and carotid and femoral arteries.

In the latest report from the Bogalusa Heart Study, the prevalence of carotid and femoral artery atherosclerotic plaque was determined in asymptomatic African American and white men and women aged 29-51 years and the potential relations with cardiovascular risk factors was examined.[3] Data were analyzed from a sample of 851 subjects without a history of cardiovascular/cerebrovascular events (57% women, 70% white) who were part of the initial cohort of approximately of 16,000 children aged 4-17 years enrolled in the study from 1973 onward. They were followed from childhood through adulthood and assessed for carotid and femoral artery plaque formation defined by intima-media thickness (IMT) measured by B-mode ultrasonography.

Plaque prevalence was found to be highest in white men (14%), compared with white women (8%) and African American men and women (9%). This was consistent with findings in autopsy studies of both the Bogalusa Heart[4] and the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) studies.[5]

Analyses adjusted for age, race, and gender showed that current smoking (OR 2.3, P = .0005) was the strongest independent predictor for plaque formation, followed by hypertension (OR 2.2, P = .002), diabetes (OR 2.1, P = .02), age (OR 1.1, P =.02), and white race (OR 1.7, P = .05). Neither obesity nor dyslipidemia were independently associated with plaque in this study. Levels of triglycerides, but not low-density lipoprotein cholesterol (LDL-C) or high-density lipoprotein cholesterol (HDL-C) were significantly higher in subjects with plaques. As the researchers noted, the associations of risk factors such as smoking and diabetes with atherosclerosis are well known, but dyslipidemia is also recognized as having a strong correlation with plaque formation. They suggested that in this study, "Interventions such as diet alteration and statin therapy may have a positive impact on these potential contributors to plaque formation."

The author of an invited commentary, Dana E. King, MD, MS (Medical University of South Carolina, Charleston) suggested that the findings of this study, "while not a surprise to vascular researchers, may challenge the prevailing beliefs of some clinicians. The conclusion that obesity and LDL-cholesterol do not make a significant contribution to the development of carotid atherosclerosis may arouse some skepticism."[6] However, Dr. King noted that "recent research indeed supports the idea that LDL-cholesterol may play a lesser role in the development of atherosclerosis than was once believed," pointing out that statins, which reduce LDL-C, only reduce the risk of atherosclerosis by 30%. "These results suggest that the other 70% of the risk is unexplained and due to other non-LDL factors," Dr. King said. "We do not completely understand," he admitted, but "Great research often challenges conventional wisdom. The current study demonstrates that we still have much to learn about the common nemesis, atherosclerosis." Dr. King concluded.

Dr. Berenson spoke about the study's findings with Linda Brookes and recalled the achievements of the Bogalusa Heart Study, which is now in its last stages.

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