New obesity body mass index threshold for self-reported data.

Area of Science:

• Public Health
• Epidemiology
• Anthropometry

Background:

• Self-reported height and weight data in population studies often lead to inaccurate obesity prevalence estimates due to underreporting of weight and overestimation of height.
• A modified obesity threshold for self-reported data has been proposed to enhance accuracy.

Purpose of the Study:

• To evaluate the accuracy of a reduced obesity threshold for self-reported height and weight.
• To determine an optimal body mass index (BMI) cut-off for self-reported data using receiver operating characteristic (ROC) curve analysis.

Main Methods:

• Comparison of self-reported versus measured height and weight in a representative Swiss adult population sample (n=13,162).
• ROC curve analysis to identify an optimal BMI cut-off for self-reported data.
• Validation of the proposed threshold on an independent French population sample (n=1,858).

Main Results:

• Obesity prevalence was underestimated using standard BMI thresholds with self-reported data (33.6% of obese men and 27.5% of obese women misclassified).
• A reduced BMI cut-off of 29.2 kg/m² for self-reported data significantly reduced misclassification to 17.9% in men and 16.9% in women.
• Validation in the French sample confirmed the effectiveness of the lower threshold.

Conclusions:

• A reduced BMI threshold (29.2 kg/m²) for self-reported data improves the estimation of obesity prevalence.
• This adjusted threshold is recommended for use in population studies analyzing self-reported anthropometric data.