Evaluation of quality control procedures for 24-h dietary recalls: results from the Girls health Enrichment Multisite Studies

Background. Quality control methods are key components of dietary assessment, but have rarely been evaluated. Methods. One hundred forty-four 8-10-year-old African-American girls at three field centers completed two 24-h dietary recalls at baseline before a pilot weight gain prevention intervention (one recall collected in-person and one by telephone). The dietary recall data were initially reviewed by the dietary interviewer (Phase 1), then by a local lead nutritionist at the field center (Phase 2), and then by the Nutrition Coordinating Center (NCC) (Phase 3); any differences identified by NCC were reconciled (Phase 4). Bland-Altman and generalizability theory methods were used to assess agreement of consumption for selected food variables and nutrients between phases. Results. Only small differences occurred. Quality control procedures primarily reduced the variances of nutrients rather than caused the means to shift. Most of the variability among phases was due to individual level variability in dietary intake. Conclusions. Decisions to review dietary recall data beyond local review should be based on the level of precision and accuracy required for the study outcomes and the availability of financial resources. (C) 2004 The Institute For Cancer Prevention and Elsevier Inc. All rights reserved.