Welcome to the Muscatine Heart Study

Dr. Ronald Lauer and his colleagues at The University of Iowa initiated The Muscatine Heart Study on November 17, 1970 when the first school survey examinations were conducted at Grant Elementary School in Muscatine, Iowa. The initial purpose of the Muscatine Heart Study was to define the distribution of established adult cardiovascular risk factors in school-aged children and to characterize the tracking of risk factor levels throughout childhood into adulthood. Between 1970 and 1981, 11,377 students from Muscatine participated in the six biennial school survey examinations; some participated in one, but many participated in all six examinations. The Muscatine Heart Study is the longest running study of cardiovascular risk factors in children in the United States. Many of the earliest school survey participants, along with their children, are still involved with the Muscatine Heart Study.

The Muscatine Heart Study

Why Muscatine?

"The school children of Muscatine, Iowa, were selected ... for this study, not only because of their geographic proximity to ... Iowa City but also because of the stability of the school population ... 1963 to 1968 school terms, ... found a mean of 98% of each grade level of students progressing from one grade to the next and thus remaining in the Muscatine school system.” Lauer et al., Coronary Heart Disease Risk Factors in School Children: The Muscatine Study. J Pediatr. 1975;86:697-706.

School Surveys

In six biennial school surveys conducted between 1970 and 1981, a total of 11,377 school children from Muscatine, Iowa (predominantly of Northern European origin) underwent 26,919 examinations that measured body size and risk factor levels (School Surveys)

Blood pressure and cholesterol measurements from these school survey examinations, along with measurements from examinations of other childhood populations, were used to establish reference percentiles that could be used by physicians and school nurses caring for children

Young Adult Follow-up Surveys

Between 1982 and 1991, 2,547 individuals who had been examined during childhood were again examined at ages 20 to 38 years (Young-Adult Follow-up Surveys), body size and risk factor levels were obtained and a health history questionnaire was completed

The Muscatine Study Longitudinal Adult Cohort

Since the early 1990s, the latest vascular imaging technology has been used to measure the early atherosclerotic process in a representative cohort (N=865 representing approximately 625 families) of the childhood participants (the Muscatine Study Longitudinal Adult Cohort), with non-invasive measures of coronary artery calcium (CAC), carotid artery intimal-medial thickness (IMT), and brachial artery flow-mediated dilatation (FMD) that allow an assessment of subclinical vascular disease.

Family Studies

The Muscatine Heart Study has also conducted several family studies that have each focused on a different cardiovascular risk factor (cholesterol, blood pressure, triglycerides, body size). Probands for these family studies were identified based on survey risk factor profiles of participating students. For example, The Ponderosity Family Study focused on families of four groups of students: a random sample who participated in all three school surveys conducted in 1977, 1979 and 1981; those who were in the lowest quintile of relative weight at all three surveys; those who were in the highest quintile of relative weight at all three surveys; and those whose relative weight increased by at least two quintiles over the three-survey period.

The Muscatine Study Offspring Cohort

The Muscatine Heart Study Offspring Cohort was established beginning in 2001 for the purpose of investigating associations between cardiovascular risk factors, carotid (cIMT) and abdominal aortic (aIMT) IMT obtained from ultrasound examinations during adolescence and young adulthood. This Cohort currently includes 719 offspring of the Longitudinal Adult Cohort members, representing 395 families.

What Have We Found?

Results from Muscatine Heart Study investigations to date were among the first to demonstrate that:

• Levels of cholesterol, blood pressure and body mass index track throughout childhood
• Elevated childhood levels of cholesterol, blood pressure, and body mass index are predictive of elevated adult levels
• Children with high cholesterol levels have a significantly higher proportion of first- and second-degree relatives with a cardiovascular cause of death than children with normal cholesterol levels
• Obese children have higher blood pressure levels than lean children
• Obese hypertensive children have a significantly higher proportion of first- and second-degree relatives with a cardiovascular cause of death than obese children with normal blood pressure
• Childhood and concurrent elevated cardiovascular risk factor levels are associated with greater carotid artery intimal-medial thickness (IMT) in young and middle-aged adults
• Coronary artery calcium is evident in 30% of males, ages 29 to 37 years, and 16% of females, ages 29 to 43 years, and is associated with childhood and concurrent cardiovascular risk factor levels
• There is an association between carotid artery intimal-medial thickness and calcium in the coronary arteries
• Cardiovascular risk factors are more strongly associated with abdominal aortic IMT than with carotid IMT in young (mean 14.7 years; range 11 to 35 years) individuals

The Muscatine Heart Study has a strong history of multidisciplinary collaborative research. The current investigators represent seven departments in three University of Iowa colleges (Medicine [Departments of Pediatrics, Radiology, Neurology, and Pathology], Public Health [Biostatistics and Epidemiology] and Engineering [Electrical and Computer Engineering]).

Current Muscatine Heart Study investigations are focused on:

1. determining whether established risk factors measured during childhood and early adulthood and putative risk factors measured during adulthood are associated with CAC, carotid IMT and brachial FMD;
2. conducting pilot imaging studies of the retina (photographs) and brain (MRI), and cognitive function testing, in addition to obtaining childhood ITBS results to investigate risk factor associations
3. identifying genotypes that are associated with childhood, adolescent and adult cardiovascular risk factor levels, with patterns of risk factor tracking from childhood to adulthood, and with early manifestations of the atherosclerotic process as measured by CAC, carotid IMT and brachial FMD;
4. measuring carotid and abdominal aortic IMT in adolescent and young-adult offspring of Longitudinal Adult Cohort members; and
5. conducting a new middle school survey.