Reproducibility, power and validity of visual analogue scales in assessment of appetite sensations in single test meal studies.

OBJECTIVE: To examine reproducibility and validity of visual analogue scales (VAS) for measurement of appetite sensations, with and without a diet standardization prior to the test days.
DESIGN: On two different test days the subjects recorded their appetite sensations before breakfast and every 30 min during the 4.5 h postprandial period under exactly the same conditions.
SUBJECTS: 55 healthy men (age 25.6+/-0.6 y, BMI 22.6+/-0.3 kg¿m2). MEASUREMENTS: VAS were used to record hunger, satiety, fullness, prospective food consumption, desire to eat something fatty, salty, sweet or savoury, and palatability of the meals. Subsequently an ad libitum lunch was served and energy intake was recorded. Reproducibility was assessed by the coefficient of repeatability (CR) of fasting, mean 4.5 h and peak/nadir values.
RESULTS: CRs (range 20-61 mm) were larger for fasting and peak/nadir values compared with mean 4.5 h values. No parameter seemed to be improved by diet standardization. Using a paired design and a study power of 0.8, a difference of 10 mm on fasting and 5 mm on mean 4.5 h ratings can be detected with 18 subjects. When using desires to eat specific types of food or an unpaired design, more subjects are needed due to considerable variation. The best correlations of validity were found between 4.5 h mean VAS of the appetite parameters and subsequent energy intake (r=+/-0.50-0.53, P<0.001).
CONCLUSION: VAS scores are reliable for appetite research and do not seem to be influenced by prior diet standardization. However, consideration should be given to the specific parameters being measured, their sensitivity and study power. International Journal of Obesity (2000)24, 38-48