Epidemiology of Carotid Disease in Elderly Adults
To determine whether a population with isolated systolic hypertension (ISH) had a higher prevalence of carotid disease than a normotensive population matched for age and sex, and to determine specific risk factors for carotid disease.
Carotid Artery Diseases
|Study Design:||Observational Model: Natural History|
|Study Start Date:||July 1988|
|Estimated Study Completion Date:||June 2003|
The Systolic Hypertension in the Elderly Program was a multicenter controlled clinical trial supported by the NHLBI to study the cardiovascular and psychological effects of isolated systolic hypertension in the elderly and to determine the efficacy and evaluate possible adverse effects of drug treatment for this condition. A total of 4,736 patients were followed until 1991. Elderly individuals with isolated systolic hypertension are clearly at increased risk of both heart attack and stroke. This group has been shown in pilot studies to also have high prevalence of carotid disease and lower extremity arterial disease. Selected risk factors such as older age, male sex, and smoking were found to be related to an increased prevalence of disease. This study allowed validation of these initial observations.
This study was ancillary to the Systolic Hypertension in the Elderly Program (SHEP) clinical trial. Participants of the SHEP at the University of Pittsburgh were used for the hypertensive population. Patients screened for SHEP but rejected because of normal blood pressure were used for the controls. Carotid disease was assessed by duplex scanning, a noninvasive technique that combined real time B-mode ultrasound with Doppler ultrasound, producing a system capable of both vessel imaging and analysis of blood flow characteristics. Other evaluations included ankle systolic blood pressure measurements to detect lower extremity arterial disease, complete history and physical examination, electrocardiogram, blood lipoprotein levels, fasting insulin and glucose levels, hemoglobin, and hematocrit. Thus, the effects of various risk factors on the development of carotid atherosclerosis were evaluated as well as the relationship between carotid atherosclerosis and peripheral arterial disease of the lower extremities. The first six months of the study consisted of preparation and reproducibility testing of duplex scan measurements. During the following three years, duplex scans and other evaluations were completed on all 400 participants. During the final half of the fourth year, the first 100 duplex scans of hypertensive participants were repeated to determine whether it was possible to measure disease progression using this methodology. The study began in FY 1988 under R29HL39871 and continued in FY 1993 under R01HL50439.
The study was renewed in 1998 for an additional three years through June, 2003. The study continued to investigate the prevalence and prognostic value of subclinical atherosclerosis in the Pittsburgh SHEP cohort and a cohort of normotensive controls. Annual telephone follow-up of the remaining 178 SHEP participants and 168 controls continued. A final clinic visit included measures of coronary and aortic calcification using electron beam computed tomography (CT), pulse wave velocity as a measure of aortic stiffening and cognitive function testing. For the Pittsburgh SHEP cohort, the antihypertensive treatment effect was striking with event rates for the active and placebo groups continuing to diverge beyond the end of SHEP. Successful demonstration of a treatment effect on coronary calcium scores would be the first randomized data showing an antihypertensive effect directly in the coronary arteries. Risk factors for coronary calcification were evaluated, producing data of a type not yet available in the literature for older adults and not being collected in any other ongoing studies of the elderly. The added measures of vascular stiffness supplemented the extensive data on subclinical atherosclerosis already available for this cohort. The extent to which these measures predicted cardiovascular events was evaluated.
|Investigator:||Kim Tyrrell||University of Pittsburgh|