The Validity of Obesity Based on Self-reported Weight and Height: Implications for Population Studies*

Department of Psychology, Lund University, Lund, Skåne, Sweden
Obesity (Impact Factor: 3.73). 02/2007; 15(1):197-208. DOI: 10.1038/oby.2007.536
Source: PubMed

ABSTRACT

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.
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.
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.
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.

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    • "This resulted in our sample size being reduced by approximately 15%. Furthermore, the collection of self-reported height and weight may have resulted in poor estimates of BMI, as has been demonstrated in previous studies (Gosse, 2014; Nyholm et al., 2007). Although our analysis controlled for confounding variables it would have been beneficial to collect and adjust for other individual factors known to correlate with PA, such as self-efficacy or health status (Trost et al., 2002). "
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    • "weight in kilograms divided by height in metres squared) is derived by Statistics Canada using the self - reported height and weight data , excluding pregnant women . Because it is well known that individuals tend to under - report their weights and over - report their heights ( Gil and Mora , 2011 ; Gorber et al. , 2007 ; Shields et al . , 2008 ; Nyholm et al . , 2007) , we address this measurement error using the self - reported bias correction factors proposed by Gorber et al . ( 2008) ( for males : BMI corrected = À1. 08 + 1 . 08 Â BMI self - reported ; and for females : BMI corrected = À0. 012 + 1 . 05 Â BMI self - reported ) . The second exposure variable , obesity , is a binary variable equal t"
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    • "The smoking and drinking variables were then dummy coded using the " not at all " category as the reference group. Finally, following standard procedures (Nyholm et al., 2007), responses to an overall self-rated general health questionnaire item (5-point scale from very good to very bad) were dummy coded using the lowest health rating as the reference group. "
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