Home-based anthropometric, blood pressure and pulse measurements in young children by trained data collectors in the National Children's Study

Objective: The current study assessed whether home-based data collection by trained data collectors can produce high-quality physical measurement data in young children. Design: The study assessed the quality of intra-examiner measurements of blood pressure, pulse rate and anthropometric dimensions using intra-examiner reliability and intra-examiner technical error of measurement (TEM). Setting: Non-clinical, primarily private homes of National Children's Study participants in twenty-two study locations across the USA. Subjects: Children in four age groups: 5-7 months (n 91), 11-16 months (n 393), 23-28 months (n 1410) and 35-40 months (n 800). Results: Absolute TEM ranged in value from 0.09 to 16.21, varying widely by age group and measure, as expected. Relative TEM spanned from 0.27 to 13.71 across age groups and physical measures. Reliabilities for anthropometric measurements by age group and measure ranged from 0.46 to >0.99 with most exceeding 0.90, suggesting that the large majority of anthropometric measures can be collected in a home-based setting on young children by trained data collectors. Reliabilities for blood pressure and pulse rate measurements by age group ranged from 0.21 to 0.74, implying these are less reliably measured with young children when taken in the data collection context described here. Conclusions: Reliability estimates >0.95 for weight, length, height, and thigh, waist and head circumference, and >0.90 for triceps and subscapular skinfolds, indicate that these measures can be collected in the field by trained data collectors without compromising data quality. These estimates can be used for interim evaluations of data collector training and measurement protocols.