Goldbohm R A, van 't Veer P, van den Brandt P A, van 't Hof M A, Brants H A, Sturmans F, Hermus R J
TNO Nutrition and Food Research Institute, Department of Epidemiology, Zeist, The Netherlands.
Eur J Clin Nutr. 1995 Jun;49(6):420-9.
In studies on diet and cancer, diet assessment should address long-term intake. Therefore, the authors determined the 5-year reproducibility of a self-administered 150-item food frequency questionnaire (FFQ) used to assess dietary habits in the Netherlands Cohort Study on diet and cancer. Since the FFQ was repeated more than once, the pure test-retest reliability of the FFQ could be distinguished from the intra-individual change in nutrient intake over time. These results were furthermore used to investigate the measurement error structure of the FFQ.
After baseline administration in 1986, the FFQ was annually repeated from 1987 to 1991 in independent random samples of the cohort (n = 400). Pearson correlation coefficients (r) between baseline and repeated measurements of nutrient intake, calculated for each time interval, were regressed on time interval to provide separate estimates of the test-retest correlation (intercept of regression line) and of the decline in correlation over time (slope). The proportion of correlated measurement error was derived from combining the test-retest results with those from a validation study, in which the FFQ was validated against three 3-day diet records.
Response was stable at 82%. The test-retest r ranged from 0.42 for selenium intake to 0.90 for alcohol intake. The slopes of the regression lines were relatively flat, but negative for most nutrients; on average, the decline in r amounted to 0.07 after 5 years, indicating that the potential of a single FFQ measurement to rank subjects according to nutrient intake dropped only slightly over time. This is important for studies on cancer since a long induction period may be involved. It was furthermore shown that the proportion of within-subject (error) variance of the FFQ method that could be attributed to correlated error ranged from 0 to 50%. This finding confirms that a reliability study may underestimate the measurement error of a method.
Dutch Cancer Society (grants CIVO 86-1 and CIVO 90-3).
在饮食与癌症的研究中，饮食评估应关注长期摄入量。因此，作者确定了一份用于荷兰饮食与癌症队列研究中评估饮食习惯的150项自填式食物频率问卷（FFQ）的5年重现性。由于FFQ被重复使用不止一次，因此可以将FFQ的纯重测信度与个体营养素摄入量随时间的变化区分开来。这些结果还被用于研究FFQ的测量误差结构。
在1986年进行基线调查后，1987年至1991年每年对该队列的独立随机样本（n = 400）重复进行FFQ调查。计算每个时间间隔内营养素摄入量的基线测量值与重复测量值之间的Pearson相关系数（r），并将其对时间间隔进行回归，以分别估计重测相关性（回归线的截距）和相关性随时间的下降（斜率）。相关测量误差的比例是通过将重测结果与一项验证研究的结果相结合得出的，在该验证研究中，FFQ与三份3天饮食记录进行了验证。
应答率稳定在82%。重测r值范围从硒摄入量的0.42到酒精摄入量的0.90。回归线的斜率相对平缓，但大多数营养素的斜率为负；平均而言，5年后r值下降了0.07，这表明单次FFQ测量根据营养素摄入量对受试者进行排名的能力随时间仅略有下降。这对于癌症研究很重要，因为可能涉及较长的诱导期。此外还表明，FFQ方法中可归因于相关误差的受试者内（误差）方差比例范围为0至50%。这一发现证实了可靠性研究可能会低估一种方法的测量误差。
荷兰癌症协会（资助编号CIVO 86 - 1和CIVO 90 - 3）。
