Accuracy and precision of two short screeners to assess change in fruit and vegetable consumption among diverse populations participating in health promotion intervention trials

Two short frequency questionnaires, the NCI 19-item Fruit and Vegetable Screener (FVS) and a single question on overall fruit and vegetable consumption (1-item), were evaluated for their ability to assess change in fruit and vegetable (FV) consumption over time and in response to intervention among participants in 5 health promotion trials in the Behavior Change Consortium. Cross-sectional differences and correlations of FV estimates at baseline and at follow-up were compared for the FVS (n = 315) and the 1-item (n = 227), relative to multiple 24-h recall interviews (24HR). The FVS significantly overestimated daily intake by 1.27 servings at baseline amongmen and by 1.42 and 1.59 servings at baseline and follow-up, respectively, in women, whereas the 1-item measure significantly underestimated intake at both time points in men (0.98 serving at baseline, 0.75 serving at follow-up) and women (0.61 and 0.41 serving). Cross-sectional deattenuated correlations with 24HR at follow-up were 0.48 (FVS) and 0.50 (1-item). To evaluate the capacity of the 2 screeners to assess FV change, we compared mean posttest effects with 24HR by treatment group overall and by gender. Treatment group differences were not significant for either 24HR or 1-item. Among 315 subjects, the FVS treatment group differences were significant both overall and within gender but not when repeated in the sample of 227. Findings suggest multiple 24HR at multiple time points in adequate sample sizes remain the gold standard for FV reports. Biases in FVS estimates may reflect participants' lifestyles and sociodemographic characteristics and require further examination in longitudinal samples representative of diverse populations.