Incidence of Diabetes and Cardiovascular Disease in Mexican Americans
Condition: Cardiovascular Diseases; Heart Diseases; Myocardial Infarction; Angina Pectoris; Death, Sudden, Cardiac; Cerebrovascular Disorders; Peripheral Vascular Diseases; Coronary Disease; Diabetes Mellitus, Non-insulin Dependent; Diabetes Mellitus
MeSH terms: Cerebrovascular Disorders; Cardiovascular Diseases; Myocardial Infarction; Vascular Diseases; Coronary Disease; Angina Pectoris; Peripheral Vascular Diseases; Peripheral Arterial Disease; Death, Sudden, Cardiac; Diabetes Mellitus; Diabetes Mellitus, Type 2; Death, Sudden
Study type: Observational

Summary: 
      To determine the incidence of type II diabetes and cardiovascular disease among
      Mexican-American and non-Hispanic whites in a 15 to 24 year follow-up of the San Antonio
      Heart Study 1 participants. Also, to perform a 15 to 24 year mortality follow-up of the
      cohort and to examine the "Hispanic paradox".
    

Detailed description: 
      BACKGROUND:

      The San Antonio Heart Study 1 was a population-based survey of diabetes and cardiovascular
      risk factors in Mexican Americans and non-Hispanic whites conducted from 1979 to 1982.
      Participants included all men and non-pregnant women ages 24 to 64, who resided in households
      randomly sampled from three socio-culturally distinct neighborhoods of San Antonio. The
      low-income barrio residents were almost exclusively traditional Mexican-Americans. The
      middle-income neighborhood was ethnically balanced with equal numbers of Mexican Americans
      and Anglos whereas the upper income suburb was approximately 90 percent Anglo. Risk factors
      measured included obesity, glucose intolerance, hypertriglyceridemia, low levels of high
      density lipoprotein cholesterol, and blood pressure. The total number of people who were
      examined medically was 2,386, divided as follows: 1,288 Mexican Americans; 929 Anglos; and
      169 other Hispanics such as Cubans. The San Antonio Heart Study 1 was designed to test the
      hypothesis that as Mexican Americans became progressively more affluent and accultured to
      mainstream United States culture, they would gradually lose their diabetic pattern of
      cardiovascular risk factors of obesity, diabetes, and hypertriglyceridemia.

      Mexican Americans are the second largest minority group in the United States. Despite this,
      as recently as 1977, little was known about their health status. In recent years this
      situation has begun to change with publication of results from several major studies
      including the San Antonio Heart Study, the Starr County Study, and most recently the Hispanic
      Health and Nutrition Examination Survey (HHANES).

      DESIGN NARRATIVE:

      Beginning in 1987, each participant in the prospective San Antonio Heart Study 1 was recalled
      as close as possible to the eighth anniversary of his or her baseline examination and
      re-examined. Subjects had fasting lipid and lipoprotein determinations, a glucose tolerance
      test to diagnose incident cases of non-insulin dependent diabetes mellitus according to the
      National Diabetes Data Group criteria, blood pressure measurements, a resting
      electrocardiogram, and completed a questionnaire to elicit information on possible
      cardiovascular endpoints. Medical records were obtained to document the endpoints. Subjects
      with a history of peripheral vascular disease or diabetes had ankle/arm blood pressure ratios
      determined before and after exercise. Deaths were ascertained in the course of routine
      follow-up supplemented by search of state health department and National Death Index records.
      Death certificates were requested and for those certificates indicating diabetes or
      cardiovascular disease as the cause of death, hospital or physician records were requested
      and reviewed. Standardized criteria were used to validate cause of death. Endpoints included
      diabetes, sudden cardiac death, non-fatal (including silent) myocardial infarction, angina
      pectoris, cerebrovascular and peripheral vascular disease. The study was renewed in 1992 to
      continue follow-up.

      The study was renewed in 1998 to perform a 15 to 24 year mortality follow-up of the cohort.
      Time dependencies in the ethnic mortality ratio were examined as well as other covariates
      such as biochemical parameters, hemodynamic variables, and anthropometric variables such as
      socioeconomic status, health care access and utilization and migrant status. A sample of 200
      Mexican-American and 200 non-Hispanic white death certificates were verified by medical
      record review. The purpose of the review was to determine whether Mexican Americans, deemed
      to have died of cardiovascular causes based on medical record review, were more or less
      likely to have cardiovascular codes (ICDA 390-459) listed on their death certificates than
      non-Hispanic whites deemed to have died of these causes. The review aided in the
      interpretation of data relating to possible ethnic differences in cause-specific mortality
      based on death certificate coding.

      The study should help to explain whether the "Hispanic paradox" is an artifact of
      underascertainment of deaths in this group. The "Hispanic paradox" refers to the concept that
      all-cause and cardiovascular (CV) mortality are widely thought to be lower in Hispanics,
      including Mexican Americans, than in non-Hispanic whites in the United States. Preliminary
      mortality data from this study suggest that all-cause mortality is actually higher in Mexican
      Americans than in non-Hispanic whites in San Antonio.