title: Validity of self-reported weight and height in Austrian adults: sociodemographic determinants and consequences for the classification of BMI categories.
abstract: OBJECTIVE
  Epidemiological studies have shown that adults tend to underestimate their weight and overestimate their height. This may lead to a misclassification of their BMI in studies based on self-reported data. The aim of the present study was to assess the validity of self-reported weight and height in Austrian adults.
  
  
  METHODS
  Data on weight, height, health behaviour and sociodemographic characteristics of adults were collected in a standardized procedure via a self-filling questionnaire and a medical examination including measurements of weight and height.
  
  
  METHODS
  A publicly accessible out-patient clinic in southern Austria.
  
  
  METHODS
  Austrian residents (n 473) aged 18 years and older who attended a health check participated in the study.
  
  
  RESULTS
  The mean difference between reported and measured BMI was not significant in younger adults (<35 years: mean difference -0·21 kg/m2; P < 0·08) but increased significantly with age (≥55 years: mean difference -0·68 kg/m2; P < 0·001). The prevalence of normal weight (BMI = 18·5-24·9 kg/m2) and overweight (BMI = 25·0-29·9 kg/m2) was overestimated based on the self-reported data on BMI, while that for underweight (BMI < 18·5 kg/m2) and obesity (BMI ≥ 30·0 kg/m2) was underestimated (P < 0·001). The self-reported data showed an obesity prevalence of 12·5 %, while measurement showed a prevalence of 15·4 % (P < 0·001).
  
  
  CONCLUSIONS
  Our results indicate that prevalence rates of obesity are probably underestimated for Austrian adults when using self-reported weight and height information. The deviations from the measured data clearly increased with age. Analyses based on self-reported data should therefore be adjusted for the age dependency of the validity.
authors.affiliation: Clinical Department of Gynaecology, Medical University Graz, Auenbruggerplatz 14, A-8010 Graz, Austria. franziska.grossschaedl@medunigraz.at
authors.forename: Franziska
authors.initials: F
authors.lastname: Großschädl
authors.forename: Bernd
authors.initials: B
authors.lastname: Haditsch
authors.forename: Willibald J
authors.initials: WJ
authors.lastname: Stronegger
mesh_terms: D000328:Adult; D001317:Austria / Q000453:epidemiology; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000453:epidemiology*; D010045:Outpatients; D015995:Prevalence; D015203:Reproducibility of Results; D057566:Self Report; D012959:Socioeconomic Factors; D013851:Thinness / Q000453:epidemiology*; D044465:White People