Validity and reliability of foods and beverages intake obtained by telephone survey in Belo Horizonte, Brazil.

OBJECTIVE

To evaluate the validity and reproducibility markers of food and beverage intake obtained by means of a telephone-based surveillance system.

METHODS

Reproducibility was assessed by means of repeated interviews with a 7-15 day interval after the first interview of the system (n=258). Validity was analyzed based on three interviews corresponding to the 24 hour recall method, used as gold standard, 3 days a week, 7 to 15 days after the original telephone interview (n=217). In the study of reproducibility, kappa statistics was used to measure the similarity between the results of the proportions obtained in the first and second interviews. For validation, the proportion of positive reports regarding foods and beverages at the original telephone interview was compared to that obtained by the 24 hour recall method, and the results was analyzed by calculating sensitivity, specificity and positive predictive value.

RESULTS

In the reproducibility study, the agreement was almost perfect for the marker milk consumption (0.86), substantial for fruit consumption (0.67), intake of fruits and vegetables, intake of meat with fat and alcohol abuse. The agreement was moderate for the intake of soft drink, and fair for the consumption of vegetables. Regarding the validity, there was an underestimation of fruit, vegetable and milk consumption, except for meat and alcohol when compared with the consumption frequency estimated from the three 24-hours recalls, differences related to soft drink consumption was inexpressive.

CONCLUSION

The instruments enabled the surveillance of factors which were potentially associated with chronic diseases, however, it is a priority to continue with validation studies in other populations to provide greater system reliability, always considering possible limiting factors.