Validity assessment of a portable anthropometer to measure length in 24-month children from the 2015 Pelotas Birth Cohort.

OBJECTIVE This study aimed to assess the validity of a portable anthropometer against the gold standard among 2-year-old infants from the 2015 Pelotas (Brazil) Birth Cohort. DESIGN Birth cohort study. SETTING A fixed Harpenden® infant anthropometer was considered as the gold standard for measuring infant length due to its greater precision and stability. The portable SANNY® (model ES2000) anthropometer was the instrument to be validated. The acceptable mean difference in length between the anthropometers was 0·5 cm. In order to compare length estimates, the interviewers carried out two length measures for each of the anthropometers (fixed and portable) and for each child. The mean of the two lengths was calculated for each anthropometer, and their difference was calculated. PARTICIPANTS A subsample of 252 24-month-old members of the 2015 Pelotas (Brazil) birth cohort study. RESULTS Children's mean age was 23·5 months. According to Bland-Altman plot, there were no differences in overall lengths between the portable and the fixed anthropometers, or in lengths according to sex. There was a high overall concordance between the length estimates of the fixed and portable anthropometers (ρ = 0·94; 95 % CI 0·92, 0·95). CONCLUSIONS The portable anthropometer proved to be accurate to measure the length of 24-month-old infants, being applicable to studies using the same standardised protocol used in the present study.