Bias in self-reported height and weight in a cohort of young adults – perspectives for cardio-metabolic risk prevention programmes
Authors: Lynggaard V , Soendergaard S M , Boettcher M , Stampe L , Kempel M K , Winding T N 
Published: October 2022

Abstract

Background
Precise assessment of obesity is essential in evaluating and applying preventive strategies to avoid adverse cardio-metabolic risk profiles later in life. Self-reported measures of height and weight is often used in cohort and cross-sectoral studies due to practical and financial reasons. However, bias due to self-reporting is well known with risk of overestimation of height and underestimation of weight. The latter is particular reported among women and persons with obesity. Little is known about the influence of educational factors in the self-reporting of height and weight. To gain insight into the extent to which different factors bias self-reporting, is important to assess the validity of self-reported body mass index (BMI) within groups of people with certain characteristics.

Purpose
The aim was to investigate the validity of self-reported height and weight versus objective measured height and weight. Additionally, the study aimed to examine if sex, measured BMI, and educational factors biased the self-reporting differenially.

Methods
The study included 264 participants, all aged 28 years who were a sub-sample from an ongoing cohort in Central Denmark Region. The participants attended a physical health examination, including measures of height and weight after having self-reported these not knowing they were to be objectively measured later. Data of their own and parental educational levels were drawn from registries. Paired t-tests were used to assess the descriptive differences between self-reported and measured values and linear regression was used to assess the independent effects of sex, education, and BMI on the differences. In model 1 adjustment for all other variables except for BMI was conducted and full adjustments were made in model 2.

Results
Overall, participants overestimated their height by 0.89 (0.67; 1.10) cm and underestimated their weight by 2.47 (1.78; 3.17) kg (Table 1). Female sex was found to independently bias underreporting of weight (β −1.51 (−2.86; −0.15)) and male sex overestimated height (β 0.83 (0.38; 1.27) (Table 2). Additionally, being overweight or obese also independently biased the underestimation of self-reported weight ((β 2.23 (0.64; 3.83) and β 5.22 (3.51; 6.94)) (Table 2). Additionally, participants with overweight were less likely to overestimate their height compared to those with normal weight. Without adjustments for BMI, low level of education also biased underestimation of weight significantly (Table 2).

Conclusion
Women and persons with obesity in particular underestimated weight. Participants with lower level of education also underestimated weight but this was explained by obesity. Men overestimated their height but participants with obesity were less likely to overestimate height compared to normal weighty. When screening for overweight and obesity to initiate interventions to prevent cardio-metabolic diseases, the lack of accuracy in self-reported values must be taken into account.

Funding Acknowledgement
Type of funding sources: None.