The following analysis is based on the combined 2001-2006 data from the continuous National Health and Nutrition Examination Survey (NHANES) conducted by the National Center for Health Statistics (NCHS). The NHANES surveys are multi-stage probability samples of the non-institutionalized U.S. civilian population. Both physical measurement and self-reported height and weight information are collected in the NHANES for the same individuals, with the questionnaire preceding the physical examinations. Physical examinations take place in mobile examination centers and body measurements are based on standard protocols [20 ]. The overall unweighted NHANES response rates for the interview samples of the three continuous two-year surveys were 84% (2001-2002), 79% (2003-2004), and 80.5% (2005-2006) [21 ].
The combined 2001-2006 NHANES sample includes 17,176 adults. Of these, 15,662 (91.2%) had BMI values based on physical measures of height and weight, and 16,579 (96.5%) had BMI values based on self-reported height and weight. For 15,161 (88.3%) adult NHANES participants, both self-reported and measured BMI indicators were available for analysis. Among these, 15,155 adults also provided responses to the question: "Have you EVER been told by a doctor or health professional that you have diabetes or sugar diabetes?" Response rates for the height and weight information were lower among older respondents (particular those over 70 years of age) and among Hispanics compared to whites and African Americans, largely due to lower response rates for the measured height and weight data. Gender differences were generally small, with men having slightly better response rates.
For comparison estimates, self-reported data from the 2001-2006 National Health Interview Survey (NHIS) Sample Adult components were also analyzed. The NHIS is a household, multi-stage probability sample survey conducted annually by NCHS and fielded by the U.S. Census Bureau for the Centers for Disease Control and Prevention's National Center for Health Statistics [22 ]. The sample size for the combined 2001-2006 NHIS Sample Adult interview was 182,251 adults. Of these, 95.3% had BMI values based on their self-reported height and weight. The average annual response rate for the 2001-2006 NHIS household surveys was 88%; the final response rate for the Sample Adult component (for which self-response is required) was 72%.
The weight history section of the NHANES interview contained the following two questions: (1) "How tall are you without shoes?" This question could be answered by the respondent in terms of feet and inches or meters and centimeters; and (2) "How much do you weigh without clothes or shoes?" This question could be answered in terms of pounds or kilograms. The parallel NHIS questions were: (1) "How tall are you without shoes?" and (2) "How much do you weigh without shoes?"
Both the NHANES and NHIS surveys are subject to the CDC/NCHS Ethics Review Board (ERB) to ensure that appropriate human subjects protections are provided, in compliance with 45 CFR part 46. All statistical analyses were carried out with STATA 10.1 software [23 ], using the "svy" command to incorporate information on the appropriate weights, primary sampling units and strata for correct variance estimation. This analysis is limited to the adult (18 years and over) samples in both surveys. Estimates are age-standardized based on the 2000 U.S. Census results, using 10-year age intervals.
The combined 2001-2006 NHANES sample includes 17,176 adults. Of these, 15,662 (91.2%) had BMI values based on physical measures of height and weight, and 16,579 (96.5%) had BMI values based on self-reported height and weight. For 15,161 (88.3%) adult NHANES participants, both self-reported and measured BMI indicators were available for analysis. Among these, 15,155 adults also provided responses to the question: "Have you EVER been told by a doctor or health professional that you have diabetes or sugar diabetes?" Response rates for the height and weight information were lower among older respondents (particular those over 70 years of age) and among Hispanics compared to whites and African Americans, largely due to lower response rates for the measured height and weight data. Gender differences were generally small, with men having slightly better response rates.
For comparison estimates, self-reported data from the 2001-2006 National Health Interview Survey (NHIS) Sample Adult components were also analyzed. The NHIS is a household, multi-stage probability sample survey conducted annually by NCHS and fielded by the U.S. Census Bureau for the Centers for Disease Control and Prevention's National Center for Health Statistics [22 ]. The sample size for the combined 2001-2006 NHIS Sample Adult interview was 182,251 adults. Of these, 95.3% had BMI values based on their self-reported height and weight. The average annual response rate for the 2001-2006 NHIS household surveys was 88%; the final response rate for the Sample Adult component (for which self-response is required) was 72%.
The weight history section of the NHANES interview contained the following two questions: (1) "How tall are you without shoes?" This question could be answered by the respondent in terms of feet and inches or meters and centimeters; and (2) "How much do you weigh without clothes or shoes?" This question could be answered in terms of pounds or kilograms. The parallel NHIS questions were: (1) "How tall are you without shoes?" and (2) "How much do you weigh without shoes?"
Both the NHANES and NHIS surveys are subject to the CDC/NCHS Ethics Review Board (ERB) to ensure that appropriate human subjects protections are provided, in compliance with 45 CFR part 46. All statistical analyses were carried out with STATA 10.1 software [23 ], using the "svy" command to incorporate information on the appropriate weights, primary sampling units and strata for correct variance estimation. This analysis is limited to the adult (18 years and over) samples in both surveys. Estimates are age-standardized based on the 2000 U.S. Census results, using 10-year age intervals.
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