Validity of a telephone-administered 24-hour dietary recall in telephone and non-telephone households in the rural Lower Mississippi Delta region.

Objective: To determine if 24-hour dietary recall data are influenced by whether data are collected by telephone or face-to-face interviews in telephone and non-telephone households.

Design: Dual sampling frame of telephone and non-telephone households. In telephone households, participants completed a 24-hour dietary recall either by face-to-face interview or telephone interview. In non-telephone households, participants completed a 24-hour dietary recall either by face-to-face interview or by using a cellular telephone provided by a field interviewer.

Subjects/setting: Four hundred nine participants from the rural Delta region of Arkansas, Louisiana, and Mississippi.

Main Outcome Measures: Mean energy and protein intakes.

Statistical Analyses Performed: Comparison of telephone and non-telephone households, controlling for type of interview, and comparison of telephone and face-to-face interviews in each household type using unpaired t tests and linear regression, adjusting for gender, age, and body mass index.

Results: Mean differences between telephone and face-to-face interviews for telephone households were -171 kcal (P = 0.1) and -6.9 g protein (P = 0.2), and for non-telephone households -143 kcal (P = 0.6) and 0.4 g protein (P = 1.0). Mean differences between telephone and non-telephone households for telephone interviews were 0 kcal (P = 1.0) and -0.9 g protein (P = 0.9), and for face-to-face interviews 28 kcal (P = 0.9) and 6.4 g protein (P = 0.5). Findings persisted when adjusted for gender, age, and body mass index. No statistically significant differences were detected for mean energy or protein intake between telephone and face-to-face interviews or between telephone and non-telephone households.

Applications/conclusions: These data provide support that telephone surveys adequately describe energy and protein intakes for a rural, low-income population.