Relative validity of multiple telephone versus face-to-face 24-hour dietary recalls

The relative validity of multiple telephone 24-hour dietary recalls was evaluated in a feasibility study within the framework of a large prospective investigation on the cause of chronic disease in women. Forty-nine women were interviewed four times both face-to-face and by telephone. Comparison of the total number of calories and intake of protein, carbohydrate, total and saturated fats, cholesterol, fiber, sodium, potassium, calcium, vitamin A, and vitamin C as estimated by multiple face-to-face and telephone interviews revealed an acceptable relative validity for the telephone procedure. Analysis of the position variation in the distribution (percent agreement) comparing the two procedures showed that a change in the distribution of none or one quintile occurs in more than 70% of individuals for all nutrients but vitamin C (69.4%), cholesterol (61.2%), and vitamin A (51.4%). Correlation coefficient analysis showed similar results. Adjustment for nutrient densities did not affect the overall results. Multiple 24-hour telephone dietary recalls appear to be a valid alternative to face-to-face interviews in population studies.