Methods and Limitations
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Methodology

We estimated the number and prevalence of self-reported cardiovascular disease conditions among the U.S. diabetic population aged 35 years and older using data from the National Health Interview Survey (NHIS) of the National Center for Health Statistics (NCHS), Centers for Disease Control and Prevention (CDC). Conducted continuously since 1957, NHIS is a health survey of the civilian, noninstitutionalized, household population of the United States. The survey provides information on the health of the United States population, including information on the prevalence and incidence of disease, the extent of disability, and the use of healthcare services. The multistage probability design of the survey has been described elsewhere.1,2

Adult respondents are asked whether a health professional had ever told them they had diabetes. To exclude gestational diabetes, women are asked whether they had been told they had diabetes other than during pregnancy. Adult respondents are asked whether a health professional had told them that they had coronary heart disease, angina, a heart attack, any other kind of heart condition or heart disease or a stroke. For our analyses coronary heart disease was defined as a positive response to one of the questions about coronary heart disease, angina, or heart attack. Responses to the questions on any other heart condition and stroke are analyzed separately. Any cardiovascular disease condition was defined as coronary heart disease (as previously defined), or any other kind of heart condition, or a self-reported history of stroke. The respondents who chose “don’t know,” “refused,” or did not respond to any of the above questions were excluded from data analyses. To calculate the number of persons with diabetes with cardiovascular disease conditions, the prevalence of these conditions were applied to the total number of persons with diabetes.

The prevalence estimates of self-reported cardiovascular disease in the diabetic population are presented by age, race, ethnicity, and sex. Three-year averages were used to improve the precision of the annual estimates. Persons of Hispanic origin may be of any race. The race groups include persons of both Hispanic and non-Hispanic origin. Estimates were age-adjusted using estimates of the 2000 U.S. population as the standard.  
 

Limitations

About one-third of persons with diabetes are unaware they have diabetes because their diabetes has not been diagnosed.3 Therefore, these data can not describe the burden of cardiovascular disease among persons with undetected diabetes. In addition, NHIS data on history of diabetes and cardiovascular disease conditions are self-reported; however, studies have found self-reported cardiovascular conditions to be high in accuracy or only slightly higher than physician-reported rates,4-7 and the validity of self-reported diabetes is high for those with diagnosed diabetes.8-10 
 

References

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  2. Botman SL, Moore TF, Moriarity CL, Parsons VL. Design and estimation for the National Health Interview Survey, 1995-2004. National Center for Health Statistics. Vital and Health Statistics. Series 2, No. 130, 2000;2(130).
  3. Harris MI, Flegal KM, Cowie CC, Eberhardt MS, Goldstein DE, Little RR, Wiedmeyer HM, Byrd-Holt DD. Prevalence of diabetes, impaired fasting glucose, and impaired glucose tolerance in U.S. adults. The Third National Health and Nutrition Examination Survey, 1988-1994. Diabetes Care 1998;21:518–24.
  4. Kehoe R, Wu S-Y, Leske MC, Chylack LT Jr. Comparing self-reported and physician-reported medical history. Am J Epidemiology 1994;139:813–818.
  5. Engstad T, Bønaa, Viitanen M. Validity of self-reported stroke. The Tromso Study. Stroke 2000;31:1602–1607.
  6. Bergmann MM, Byers T, Freedman DS, Mokdad A. Validity of self-reported diagnoses leading to hospitalization: A comparison of self-reports with hospital records in a prospective study of American adults. Am J Epidemiology 1998;147:969–977.
  7. Colditz GA, Martin P, Stampfer MJ, et al. Validation of questionnaire information on risk factors and disease outcomes in a prospective cohort study of women. Am J Epidemiology 1986;123:894–900.
  8. O’Connor PJ, Rush WA, Pronk NP, Cherney LM. Identifying diabetes mellitus or heart disease among health maintenance organization members: sensitivity, specificity, predictive value, and cost of survey and database methods. Am J Manage Care 1998;4:335–342.
  9. Edwards WS, Winn DM, Kurlantzick V, et al. Evaluation of National Health Interview Survey diagnostic reporting. Hyattsville, Maryland: U.S. Department of Health and Human Services, Public Health Service, CDC, National Center for Health Statistics. Vital and Health Statistics.  vol 2, No. 120, 1994;2(12).
  10. Turner CF, Smith TK, Fitterman LK, et al. The quality of health data obtained in a new survey of elderly Americans: a validation study of the proposed Medicare beneficiary health status registry. J of Gerontology: Social Sciences 1997;52B:S49–S58.