Relative Validity of Interviewer-Administered 24-Hour Recalls Collected By Telephone and In-person Compared With Weighed Food Records Among Rural Sri Lankan Adults.

Quantitative dietary assessment is hindered by cost, time, and logistical burdens. Collecting 24-hour recall (24HR) dietary data by phone may be particularly advantageous in rural areas. To assess the criterion and relative validity and costs of phone compared with in-person 24HR versus observed weighed food records (WFR), a reference measure for true intake. We used a randomized crossover design to collect phone and in-person 24HRs from 103 rural Sri Lankan adults, each matched to a WFR collected on the reference day. Agreement was assessed using equivalence testing with 15% error bounds and concordance correlation coefficients. Memory and portion size estimation errors were examined using descriptive statistics. Activity-based costing was used to estimate 24HR costs using expenditures and micro-costing. Compared with WFR, respondents underreported energy intake by 263 kcal (12.6%) in phone 24HR and 229 kcal (10.9%) in in-person 24HR, primarily due to portion size misestimation. Mean intakes of protein and 6 micronutrients were equivalent between phone 24HR and WFR. Although no nutrients were equivalent for in-person recalls, the two recall methods had relative equivalence for energy, carbohydrates, fat, zinc, and niacin. The mean concordance correlation coefficient was slightly higher for phone recalls, whereas memory error was lower for in-person recalls. Costs per respondent were $254 for in-person 24HR and $186 for phone 24HR in a most likely implementation scenario. Among rural Sri Lankan adults, phone-based 24HR were comparable to in-person 24HR in estimating nutrient intakes, although both methods underestimated true intakes. Phone-based recalls were less expensive and performed at least as accurately as those collected in-person.