BACKGROUND Food frequency questionnaires (FFQs) are a commonly used method to assess dietary intake in epidemiological studies. It is important to evaluate the validity of FFQs in the population of interest. OBJECTIVE To evaluate the validity of an FFQ for measuring dietary intake in survivors of colorectal cancer (CRC), relative to a 7-day dietary record. DESIGN Dietary intake was assessed 1 year after the end of CRC treatment. Participants first completed a 7-day dietary record and 2 weeks later a 253-item FFQ that measured intake in the preceding month. PARTICIPANTS/SETTING Data were used from a subsample of participants (n=100) enrolled in an ongoing prospective study (EnCoRe study) in the Netherlands, from 2015 to 2018. MAIN OUTCOME MEASURES Estimated intakes of total energy, 19 nutrients, and 20 food groups as well as scoring adherence to the dietary recommendations of the World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) were compared between both dietary assessment methods. STATISTICAL ANALYSES PERFORMED Means and standard deviations, Spearman rank correlations corrected for within-person variation and total energy, and κ agreement between quintiles were assessed. RESULTS The median Spearman correlation corrected for within-person variation for nutrients and total energy was 0.60. Correlations >0.50 were found for 15 of 19 nutrients, with highest agreement for vitamin B-12 (0.74), polysaccharides (0.75), and alcohol (0.91). On average, 73% (range=60% to 84%) of participants were classified into the exact same or adjacent nutrient quintile. The median Spearman correlation corrected for within-person variation for food groups was 0.62. Correlations >0.50 were found for 17 of 20 food groups, with highest agreement for cereals and cereal products (0.96), fish (0.96), and potatoes (0.99). The Spearman correlation between total scores of the WCRF/AICR dietary recommendations was 0.53. CONCLUSIONS Relative to a 7-day dietary record, the validity of an FFQ for measuring dietary intake among survivors of CRC appeared moderate to good for most nutrients and food groups.

中文翻译：

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评估食物频率问卷与 7 天饮食记录相比的有效性，用于测量结肠直肠癌幸存者的膳食摄入量

背景 食物频率问卷 (FFQ) 是流行病学研究中评估膳食摄入量的常用方法。评估 FFQ 在目标人群中的有效性很重要。目的 评估 FFQ 相对于 7 天饮食记录测量结直肠癌 (CRC) 幸存者饮食摄入量的有效性。设计 CRC 治疗结束后 1 年评估膳食摄入量。参与者首先完成了 7 天的饮食记录，2 周后完成了 253 项 FFQ，测量了前一个月的摄入量。参与者/环境 数据来自于 2015 年至 2018 年在荷兰进行的一项前瞻性研究（EnCoRe 研究）招募的参与者子样本 (n=100)。 主要结果测量 估计总能量摄入量、19 种营养素、和 20 个食物组以及对世界癌症研究基金会/美国癌症研究所 (WCRF/AICR) 的饮食建议的遵守情况在两种饮食评估方法之间进行了比较。执行的统计分析评估了均值和标准差、针对人内变异和总能量校正的斯皮尔曼等级相关性以及五分之一之间的κ一致性。结果 校正人体内营养素和总能量的差异后，Spearman 相关系数的中位数为 0.60。发现 19 种营养素中的 15 种相关性 >0.50，其中维生素 B-12 (0.74)、多糖 (0.75) 和酒精 (0.91) 的一致性最高。平均而言，73%（范围 = 60% 至 84%）的参与者被归类到完全相同或相邻的营养五分之一。对食物组的人内变异进行校正的斯皮尔曼相关中位数为 0.62。20 个食物组中的 17 个发现相关性 >0.50，其中谷物和谷物产品 (0.96)、鱼 (0.96) 和土豆 (0.99) 的一致性最高。WCRF/AICR 饮食建议总分之间的 Spearman 相关系数为 0.53。结论 相对于 7 天的饮食记录，FFQ 用于测量 CRC 幸存者的饮食摄入量的有效性对于大多数营养素和食物组似乎是中等至良好。