Stanford Five-City Multifactor Risk Reduction Study
Condition: Cardiovascular Diseases; Heart Diseases; Atherosclerosis; Coronary Disease; Cerebrovascular Accident; Myocardial Infarction; Hypertension
MeSH terms: Stroke; Cardiovascular Diseases; Heart Diseases; Myocardial Infarction; Atherosclerosis; Coronary Disease; Infarction
Study type: Observational

Summary: 
      To conduct a large-scale demonstration and education project designed to evaluate the
      feasibility and effectiveness of long-term community health education directed toward
      lowering cardiovascular disease risk, morbidity, and mortality. Targeted risk factors
      included general lifestyle, smoking, blood pressure, nutrition and weight, and exercise. The
      program was evaluated by biennial cross-sectional independent surveys, longitudinal studies,
      and morbidity and mortality surveillance.
    

Detailed description: 
      BACKGROUND:

      The last fifty years of research into cardiovascular diseases have shown strong associations
      between individual risk factor levels and disease rates within and among many cultures. The
      potential for medical treatment of cardiovascular disease is limited by the insidious
      development of atherosclerosis and hypertension, the high immediate mortality of coronary
      disease and stroke, and the inadequacy of treatment for the advanced stages of cardiovascular
      disease. All of these factors, coupled with the predictable safety and general feasibility of
      individual risk factor reduction, provided the stimulus for developing community-wide
      strategies for the prevention of cardiovascular disease.

      The Stanford Three Community Study, conducted between 1972 and 1975, and the Five City
      Project (FCP) were designed to test the feasibility and effectiveness of such community-wide
      preventive approaches. Both the Three Community Study and the Five City Project have shown
      that risk factors can be reduced on a community-wide level, particularly smoking rates and
      blood pressure levels. These studies were congruent with other contemporary studies, such as
      the Belgium Heart Disease Prevention Project and the North Karelia Project.

      Despite these successes, however, there were additional questions. Would the reduction in
      risk be translated into a reduction in morbidity and mortality? The North Karelia Project was
      apparently associated with a fall in mortality as was the Belgium Heart Disease Prevention
      Program. However, the U.K. Heart Disease Prevention Project was not effective nor was the
      Multiple Risk Factor Intervention Trial in reducing mortality. It is an appropriate
      responsibility of the scientific community to inform the general public of the implications
      of this research and to give advice on the prudent preventive measures.

      DESIGN NARRATIVE:

      The study had a quasi-experimental design with two California cities, Salinas and Monterey,
      selected as intervention cities and three similar cities, San Luis Obispo, Modesto, and Santa
      Monica as control cities. The selection of cities was subject to several criteria including:
      location in Northern California; population exceeding 30,000 with a total of all five cities
      exceeding 300,000 to provide sufficient statistical power; ethnic, socioeconomic and
      demographic similarity; independence from other cities; no shared newspaper or electronic
      media between treatment and control cities and shared media markets between treatment cities;
      and independence of the two treatment cities. The education program began in 1980 after the
      completion of a baseline population survey and continued for eight years. Education methods
      included the use of television and radio, newspapers, books, pamphlets, and community
      programs developed through health departments, schools, voluntary organizations, hospitals
      and non-profit health service agencies.

      The effectiveness of the program was evaluated by population surveys in Monterey, Salinas,
      Modesto, and San Luis Obispo but not Santa Monica and by a morbidity and mortality
      surveillance system. In the initial year of the survey in 1979-1980, approximately 600 people
      in each community visited the survey center. This comprised the first independent sample of
      the community. After an average of 15 months, these same individuals returned to the survey
      center for a follow-up evaluation. This cohort sample has been studied every other year for
      five surveys to determine the process of change in cardiovascular risk and related behaviors
      over time. Five randomly-selected independent samples have been surveyed to study
      cross-sections of the community over time. Questionnaires and dietary measures were the chief
      sources of data on health-related behaviors. The questionnaire contained components on:
      demographic measures; attitude and opinion measures; health knowledge assessment related to
      prevention of heart disease and stroke; stress behavior; diet, nutrition, and weight
      behavior; smoking behavior; physical activity behavior; communication media use; and medical
      history including medication use. A random 40 percent of the initial sample completed a
      24-hour dietary recall which was re-administered in the fourth cohort survey and was also
      administered to a 50 percent random sample of the fourth independent survey. Biological
      measurements consisted of height and weight, blood pressure, resting heart rate, plasma
      thiocyanate, total cholesterol, triglycerides and cholesterol content of lipoprotein
      subfractions, expired air carbon dioxide, urinary sodium, potassium and creatinine, and an
      exercise test. Data were also collected on plasma apolipoprotein A-1 and B and on high
      density lipoprotein subfractions 2 and 3. A comprehensive dietary assessment was also
      conducted.

      Community surveillance was conducted to allow the calculation of comparable, city-specific
      rates for total mortality, cardiovascular mortality, fatal myocardial infarction, nonfatal
      myocardial infarction, fatal and nonfatal stroke. Development of the community surveillance
      system was done in close collaboration with the Minnesota Heart Health Project and the
      Pawtucket Heart Health Project to insure comparability. Only those cardiovascular disease
      events which always resulted in hospitalization were monitored and included myocardial
      infarction and stroke. Fatal cases were identified from county death certificate files. Both
      fatal and nonfatal hospitalized events were investigated by abstracting the medical records
      onto a set of standard forms. All non-hospitalized deaths were investigated by contacting the
      decedent's family for medical history and circumstances of death and by contacting the
      decedent's physician for medical information. Data were monitored on the severity of coronary
      events and on the quality of care. An Acute Coronary Care form was designed in cooperation
      with the Minnesota surveillance project and with the MONICA project. The form was field
      tested in September 1985 and was implemented retroactively on 1980 and 1981 cases.

      The study was renewed in 1992 to 1) extend morbidity and mortality surveillance by three
      years (to June 1994 for events through December 1992); 2) to extend analysis and publication
      of Five City Project (FCP) results and methods; and 3) to provide a small amount of
      incremental support to enable use of frozen plasma samples from earlier FCP population
      surveys to conduct a nested case-control study of the association of HDL subfractions and
      apolipoproteins with fatal and non-fatal cardiovascular disease. Extension of surveillance
      data collection was needed to insure the detection of any impact on morbidity and mortality
      of the significant risk factor changes that occurred in the treatment cities, compared to
      control cities, by 1986. The nested case-control study involved matching the survey and
      surveillance data sets to identify persons with documented events who participated in one of
      the five population surveys, identifying and contacting potential controls to be certain that
      they were free of CVD, and analysis of plasma samples frozen at -80 degrees centigrade for
      apolipoproteins A-I and B and HDL2,3 subfractions. This allowed multifactor assessment of the
      association between those factors and CVD in persons for whom many other variables were
      known.
    

Observational model: Cohort
Time perspective: Prospective