Improvement in dietary intake estimates through the combined use of different approaches

ABSTRACT Objective This study aimed to compare dietary intake estimates using two different methodological approaches: use of new portions obtained with the 24-Hour Diet Recall, which was applied in the current study population, and the application of calibration equations, which were estimated using the same 24h-recalls. Methods Calibration equations were estimated using linear regression. The medians and confidence intervals of energy and nutrient intakes were assessed using all the approaches. The U Mann Whitney test was applied to verify differences among dietary intakes obtained with the 24 Hour Recall and Food Frequency Questionnaire-based methods. The correlation between different measures was assessed with Spearman coefficient. Weighted Kappa was used to verify the capability of the Food Frequency Questionnaire -based methods to classify individuals in the same intake levels of the 24 Hour Recall. Results Nine of the eleven components that were analyzed using the Food Frequency Questionnaire with standard portions and calibrated had medians significantly different from those obtained using the 24 Hour Recall; only the measurements of vitamin E and energy were statistically equal. For the Food Frequency Questionnaire with 24 Hour Recall portions, only the medians of vitamin D and B12 did not significantly differ from the 24 Hour Recall medians. Finally, for the Food Frequency Questionnaire with 24 Hour Recall portions and calibrated, all components, except folate and iron, had medians statistically equal to those obtained using the 24 Hour Recall. Spearman correlation coefficients were higher for the Food Frequency Questionnaire with 24 Hour Recall portions calibrated for all the assessed components, and the values ranged from 0.27 (total fat) to 0.57 (iron). Higher Kappa correlation coefficients were found for the Food Frequency Questionnaire 24 Hour Recall portions calibrated. Conclusion Calibrated FFQ with portions estimated from the own target population obtained better estimates of dietary intake, with values considerably more similar to those obtained with the reference method.

摘要

目的 本研究旨在对比两种不同方法学路径下的膳食摄入估算结果：一是采用针对当前研究人群开展的24小时膳食回顾法（24-Hour Diet Recall）获取的全新分量数据，二是利用同一批24小时回顾数据构建校正方程后开展的估算。

方法 校正方程通过线性回归法构建。采用所有方法分别计算能量与营养素摄入量的中位数及置信区间。采用曼恩-惠特尼U检验验证24小时膳食回顾法与基于食物频率问卷（Food Frequency Questionnaire，FFQ）的膳食摄入估算结果间的差异；采用斯皮尔曼相关系数评估不同测量方式间的相关性；采用加权Kappa值验证基于食物频率问卷的方法能否将个体归类至与24小时膳食回顾法一致的摄入水平分层中。

结果 采用标准分量并经校正的食物频率问卷所分析的11项指标中，有9项的中位数与24小时膳食回顾法所得结果存在显著差异，仅维生素E与能量的测量结果无统计学差异。采用适配24小时膳食回顾法分量的食物频率问卷时，仅维生素D与维生素B12的中位数与24小时膳食回顾法结果无显著差异。而采用适配24小时膳食回顾法分量且经校正的食物频率问卷时，除叶酸与铁元素外，其余所有指标的中位数均与24小时膳食回顾法所得结果无统计学差异。针对所有分析指标，适配24小时膳食回顾法分量并经校正的食物频率问卷的斯皮尔曼相关系数更高，取值范围为0.27（总脂肪）至0.57（铁元素）。适配24小时膳食回顾法分量并经校正的食物频率问卷的加权Kappa值也更高。

结论 采用针对目标人群自身分量数据构建的校正后食物频率问卷，可获得更精准的膳食摄入估算结果，其数值与参考方法（24小时膳食回顾法）所得结果的一致性显著提升。