Validity of height and weight self-report in Mexican adults: results from the national health and aging study
Avila-Funes, J.A.; Gutiérrez-Robledo, L.M.; Ponce De Leon Rosales, S.
Journal of Nutrition Health and Aging 8(5): 355-361
2004
ISSN/ISBN: 1279-7707 PMID: 15359352 Document Number: 567838
Background: An adequate nutritional status is essential for maintaining the independence in the elderly. The height and weight self-report is considered a useful alternative for the estimation of body mass index (BMI). The validity of the self-report is an issue that has not been dealt with in developing countries. Aim: To assess the validity of the height and weight self-report in adults Mexican citizens. Design: Transversal study. Study population: 1707 persons (836 male, 871 female) were asked for their height and weight and were measured. Results: Mean (+or-standard deviation) age was 59.09 +or-9.86 SD; mean years of education was 5.51 +or-4.67 years. We found a high correlation between self-reported and measured weight (R2=0.837); the difference between both values rose along with the age (from 0.4 kg to 1.74 kg). A systematic difference between self-reported and measured height was found. Self-reported height was over-estimated, and the bias increased along with the age of the subjects (from 1.57 cm to 2.57 cm); further, over-estimation was larger in female individuals (+2.22 cm in female vs. +1.21 cm in male subjects). We calculated a linear model that predicts real height from self-reported height with moderate, although statistically significant results (R2=0.39 y 0.50, for female and male, respectively, p<0.0001). Knee height was also used to estimate "adulthood height" and thus, BMI. This method showed age-related dissimilarities, and the linear regression model yielded an unacceptably low correlation (R2=<0.10). The best method to estimate real BMI was to consider self-reported parameters. Discussion. Height and weight estimation using self-reported parameters is an acceptable method. Its precision is not so high in subjects older than 75 years. Height over-estimation is an expected finding congruent with age-related corporal changes. The estimation of height using knee height is not a useful method. Conclusion: Height and weight self-report is a valid method that may be used to accurately estimate height and weight in Mexican people.