title: Population distribution of the sagittal abdominal diameter (SAD) from a representative sample of US adults: comparison of SAD, waist circumference and body mass index for identifying dysglycemia.
abstract: BACKGROUND
  The sagittal abdominal diameter (SAD) measured in supine position is an alternative adiposity indicator that estimates the quantity of dysfunctional adipose tissue in the visceral depot. However, supine SAD's distribution and its association with health risk at the population level are unknown. Here we describe standardized measurements of SAD, provide the first, national estimates of the SAD distribution among US adults, and test associations of SAD and other adiposity indicators with prevalent dysglycemia.
  
  
  RESULTS
  In the 2011-2012 National Health and Nutrition Examination Survey, supine SAD was measured ("abdominal height") between arms of a sliding-beam caliper at the level of the iliac crests. From 4817 non-pregnant adults (age ≥ 20; response rate 88%) we used sample weights to estimate SAD's population distribution by sex and age groups. SAD's population mean was 22.5 cm [95% confidence interval 22.2-22.8]; median was 21.9 cm [21.6-22.4]. The mean and median values of SAD were greater for men than women. For the subpopulation without diagnosed diabetes, we compared the abilities of SAD, waist circumference (WC), and body mass index (BMI, kg/m(2)) to identify prevalent dysglycemia (HbA1c ≥ 5.7%). For age-adjusted, logistic-regression models in which sex-specific quartiles of SAD were considered simultaneously with quartiles of either WC or BMI, only SAD quartiles 3 (p<0.05 vs quartile 1) and 4 (p<0.001 vs quartile 1) remained associated with increased dysglycemia. Based on continuous adiposity indicators, analyses of the area under the receiver operating characteristic curve (AUC) indicated that the dysglycemia model fit for SAD (age-adjusted) was 0.734 for men (greater than the AUC for WC, p<0.001) and 0.764 for women (greater than the AUC for WC or BMI, p<0.001).
  
  
  CONCLUSIONS
  Measured inexpensively by bedside caliper, SAD was associated with dysglycemia independently of WC or BMI. Standardized SAD measurements may enhance assessment of dysfunctional adiposity.
authors.affiliation: Division of Diabetes Translation, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Henry S
authors.initials: HS
authors.lastname: Kahn
authors.affiliation: Division of Health and Nutrition Examination Surveys, National Center for Health Statistics, Centers for Disease Control and Prevention, Hyattsville, Maryland, United States of America.
authors.forename: Qiuping
authors.initials: Q
authors.lastname: Gu
authors.affiliation: Division of Diabetes Translation, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Kai McKeever
authors.initials: KM
authors.lastname: Bullard
authors.affiliation: Division of Nutrition, Physical Activity, and Obesity, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: David S
authors.initials: DS
authors.lastname: Freedman
authors.affiliation: Division of Health and Nutrition Examination Surveys, National Center for Health Statistics, Centers for Disease Control and Prevention, Hyattsville, Maryland, United States of America.
authors.forename: Namanjeet
authors.initials: N
authors.lastname: Ahluwalia
authors.affiliation: Division of Health and Nutrition Examination Surveys, National Center for Health Statistics, Centers for Disease Control and Prevention, Hyattsville, Maryland, United States of America.
authors.forename: Cynthia L
authors.initials: CL
authors.lastname: Ogden
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000886:Anthropometry; D015992:Body Mass Index; D005260:Female; D044882:Glucose Metabolism Disorders / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D012016:Reference Values; D012307:Risk Factors; D064346:Sagittal Abdominal Diameter / Q000502:physiology*; D014481:United States; D055105:Waist Circumference / Q000502:physiology*; D055815:Young Adult