Underreporting of BMI in adults and its effect on obesity prevalence estimations in the period 1998 to 2001.
OBJECTIVE
To identify the determinants of underreporting BMI and to evaluate the possibilities of using self-reported data for valid obesity prevalence rate estimations.


METHODS
A cross-sectional monitoring health survey was carried out between 1998 and 2002, and a review of published studies was performed. A total of 1809 men and 1882 women ages 20 to 59 years from The Netherlands were included. Body weight and height were reported and measured. Equations were calculated to estimate individuals' BMI from reported data. These equations and equations from published studies were applied to the present data to evaluate whether using these equations led to valid estimations of the obesity prevalence rate. Also, size of underestimation of obesity prevalence rate was compared between studies.


RESULTS
The prevalence of obesity was underestimated by 26.1% and 30.0% among men and women, respectively, when based on reported data. The most important determinant of underreporting BMI was a high BMI. When equations to calculate individuals' BMI from reported data were used, the obesity prevalence rate was still underestimated by 12.9% and 8.1% of the "true" obesity prevalence rate among men and women, respectively. The degree of underestimating the obesity prevalence was inconsistent across studies. Applying equations from published studies to the present data led to estimations of the obesity prevalence varying from a 7% overestimation to a 74% underestimation.


CONCLUSIONS
Valuable efforts for monitoring and evaluating prevention and treatment studies require direct measurements of body weight and height.
Visscher
Tommy L S
TL
Centre for Prevention and Health Services Research, National Institute of Public Health and the Environment, Bilthoven, The Netherlands. TOMMY.VISSCHER@FALW.VU.NL
Viet
A Lucie
AL
Kroesbergen
Ike H T
IH
Seidell
Jacob C
JC
D000328:Adult; D015982:Bias; D001827:Body Height / Q000502:physiology; D015992:Body Mass Index; D001835:Body Weight / Q000502:physiology; D003430:Cross-Sectional Studies; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D009765:Obesity / Q000453:epidemiology* / Q000523:psychology*; D015995:Prevalence; D012650:Self Disclosure