Validity of self-reported weight and stature in adolescents from Cuiaba, Central-Western Brazil

Objective This study assessed the agreement between self-reported and measured weight and stature in adolescents. Methods Ninety-seven students from public and private high schools of Cuiaba, in the state of Mato Grosso, Brazil (14 to 19 years old), were examined to assess the validity of self-reported weight and stature. The adolescents reported their weight and stature, which were subsequently measured by standard procedures. The body mass index was calculated from both self-reported and measured data. Weight status was classified according to body mass index Z-score and World Health Organization criteria. The differences between the self-reported and measured means were tested by the Student's paired t-test. Weighted Kappa's coefficient of agreement was used to assess the variations in weight status categorization using informed and measured data. Agreement between measurements was assessed by the Bland-Altman method and intraclass correlation coefficient. Results The means of self-reported and measured weights (p= 0.30), statures (p= 0.76) and body mass index (p= 0.47) were not significantly different. There was high agreement between self-reported and measured measurements according to intraclass correlation coefficient (weight: r= 0.99; stature: r= 0.96; body mass index: r= 0.97) and the mean agreements estimated by the Bland-Altman method were 99% for weight and 100% for stature. Conclusion Given the excellent agreement with measured data, self-reported weight and stature are considered valid to be used in epidemiological studies on adolescents of Cuiaba, Mato Grosso, Brazil.