Reliability, technical error of measurements and validity of instruments for nutritional status assessment of adults in Malaysia

INTRODUCTION: The Third National Health and Morbidity Survey Malaysia 2006 includes a nutritional status assessment of children. This study aimed to assess the inter- and intra-examiner reliability, the technical error of measurement and the validity of instruments for measuring weight, height and waist circumference.
METHODS: A convenience sample of 130 adults working in a selected office setting was chosen to participate in the study, subject to the inclusion and exclusion study criteria. Two public health nurses, trained to follow a standard protocol, obtained the weight, height and waist circumference measurements. The weight was measured using the Tanita HD-318 digital weighing scale to the nearest 0.1 kg, and Seca Beam Scale to the nearest 0.01 kg. The height was measured using the Seca Bodymeter 206 and Stadiometer, both to the nearest 0.1 cm. The waist circumference was measured using the Seca circumference measuring tape S 201, to the nearest 0.1 cm.
RESULTS: The intra-examiner reliability in descending order was weight and height followed by waist circumference. The height measurement, on average, using the test instrument, reported a recording of 0.4 cm higher than the reference instrument, with the upper and lower limits at 2.5 cm and 1.6 cm, respectively. The technical error of measurement and coefficient of variation of weight and height for both inter-examiner and intra-examiner measurements were all within acceptable limits (below five percent).
CONCLUSION: The findings of this study suggest that weight, height and waist circumference measured in adults aged 18 years and above, using the respective above mentioned instruments, are reliable and valid for use in a community survey. Limiting the number of examiners, especially for waist circumference measurements, would yield a higher degree of reliability and validity.