The validity of obesity based on self-reported weight and height: Implications for population studies.
OBJECTIVE
To validate self-reported information on weight and height in an adult population and to find a useful algorithm to assess the prevalence of obesity based on self-reported information.


METHODS
This was a cross-sectional survey consisting of 1703 participants (860 men and 843 women, 30 to 75 years old) conducted in the community of Vara, Sweden, from 2001 to 2003. Self-reported weight, height, and corresponding BMI were compared with measured data. Obesity was defined as measured BMI > or = 30 kg/m2. Information on education, self-rated health, smoking habits, and physical activity during leisure time was collected by a self-administered questionnaire.


RESULTS
Mean differences between measured and self-reported weight were 1.6 kg (95% confidence interval, 1.4; 1.8) in men and 1.8 kg (1.6; 2.0) in women (measured higher), whereas corresponding differences in height were -0.3 cm (-0.5; -0.2) in men and -0.4 cm (-0.5; -0.2) in women (measured lower). Age and body size were important factors for misreporting height, weight, and BMI in both men and women. Obesity (measured) was found in 156 men (19%) and 184 women (25%) and with self-reported data in 114 men (14%) and 153 women (20%). For self-reported data, the sensitivity of obesity was 70% in men and 82% in women, and when adjusted for corrected self-reported data and age, it increased to 81% and 90%, whereas the specificity decreased from 99% in both sexes to 97% in men and 98% in women.


CONCLUSIONS
The prevalence of obesity based on self-reported BMI can be estimated more accurately when using an algorithm adjusted for variables that are predictive for misreporting.
Nyholm
Maria
M
Skaraborg Institute, Skovde, Sweden.
Gullberg
Bo
B
Merlo
Juan
J
Lundqvist-Persson
Cristina
C
Råstam
Lennart
L
Lindblad
Ulf
U
D000328:Adult; D000367:Age Factors; D000368:Aged; D000465:Algorithms; D001827:Body Height / Q000502:physiology*; D015992:Body Mass Index; D001835:Body Weight / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D011237:Predictive Value of Tests; D015995:Prevalence; D015203:Reproducibility of Results; D012650:Self Disclosure; D012680:Sensitivity and Specificity; D012737:Sex Factors; D011795:Surveys and Questionnaires / Q000592:standards*; D013548:Sweden / Q000453:epidemiology