@Article{info:doi/10.2196/jmir.2575,
author="Lassale, Camille
and P{\'e}neau, Sandrine
and Touvier, Mathilde
and Julia, Chantal
and Galan, Pilar
and Hercberg, Serge
and Kesse-Guyot, Emmanuelle",
title="Validity of Web-Based Self-Reported Weight and Height: Results of the Nutrinet-Sant{\'e} Study",
journal="J Med Internet Res",
year="2013",
month="Aug",
day="08",
volume="15",
number="8",
pages="e152",
keywords="anthropometry; body weight; obesity; self-report; weights and measures; validation studies",
abstract="Background: With the growing scientific appeal of e-epidemiology, concerns arise regarding validity and reliability of Web-based self-reported data. Objective: The objectives of the present study were to assess the validity of Web-based self-reported weight, height, and resulting body mass index (BMI) compared with standardized clinical measurements and to evaluate the concordance between Web-based self-reported anthropometrics and face-to-face declarations. Methods: A total of 2513 participants of the NutriNet-Sant{\'e} study in France completed a Web-based anthropometric questionnaire 3 days before a clinical examination (validation sample) of whom 815 participants also responded to a face-to-face anthropometric interview (concordance sample). Several indicators were computed to compare data: paired t test of the difference, intraclass correlation coefficient (ICC), and Bland--Altman limits of agreement for weight, height, and BMI as continuous variables; and kappa statistics and percent agreement for validity, sensitivity, and specificity of BMI categories (normal, overweight, obese). Results: Compared with clinical data, validity was high with ICC ranging from 0.94 for height to 0.99 for weight. BMI classification was correct in 93{\%} of cases; kappa was 0.89. Of 2513 participants, 23.5{\%} were classified overweight (BMI≥25) with Web-based self-report vs 25.7{\%} with measured data, leading to a sensitivity of 88{\%} and a specificity of 99{\%}. For obesity, 9.1{\%} vs 10.7{\%} were classified obese (BMI≥30), respectively, leading to sensitivity and specificity of 83{\%} and 100{\%}. However, the Web-based self-report exhibited slight underreporting of weight and overreporting of height leading to significant underreporting of BMI (P<.05) for both men and women: --0.32 kg/m2 (SD 0.66) and --0.34 kg/m2 (SD 1.67), respectively. Mean BMI underreporting was --0.16, --0.36, and --0.63 kg/m2 in the normal, overweight, and obese categories, respectively. Almost perfect agreement (ie, concordance) was observed between Web-based and face-to-face report (ICC ranged from 0.96 to 1.00, classification agreement was 98.5{\%}, and kappa 0.97). Conclusions: Web-based self-reported weight and height data from the NutriNet-Sant{\'e} study can be considered as valid enough to be used when studying associations of nutritional factors with anthropometrics and health outcomes. Although self-reported anthropometrics are inherently prone to biases, the magnitude of such biases can be considered comparable to face-to-face interview. Web-based self-reported data appear to be an accurate and useful tool to assess anthropometric data. ",
issn="14388871",
doi="10.2196/jmir.2575",
url="http://www.jmir.org/2013/8/e152/",
url="https://doi.org/10.2196/jmir.2575",
url="http://www.ncbi.nlm.nih.gov/pubmed/23928492"
}