Subar A F, Ziegler R G, Thompson F E, Johnson C C, Weissfeld J L, Reding D, Kavounis K H, Hayes R B
Division of Cancer Control and Population Sciences, National Cancer Institute, Bethesda, MD 20892-7344, USA.
Am J Epidemiol. 2001 Feb 15;153(4):404-9. doi: 10.1093/aje/153.4.404.
In this study, the authors sought to determine the effects of length and clarity on response rates and data quality for two food frequency questionnaires (FFQs): the newly developed 36-page Diet History Questionnaire (DHQ), designed to be cognitively easier for respondents, and a 16-page FFQ developed earlier for the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. The PLCO Trial is a 23-year randomized controlled clinical trial begun in 1992. The sample for this substudy, which was conducted from January to April of 1998, consisted of 900 control and 450 screened PLCO participants aged 55-74 years. Controls received either the DHQ or the PLCO FFQ by mail. Screenees, who had previously completed the PLCO FFQ at baseline, were administered the DHQ. Among controls, the response rate for both FFQs was 82%. Average amounts of time needed by controls to complete the DHQ and the PLCO FFQ were 68 minutes and 39 minutes, respectively. Percentages of missing or uninterpretable responses were similar between instruments for questions on frequency of intake but were approximately 3 and 9 percentage points lower (p < or = 0.001) in the DHQ for questions on portion size and use of vitamin/mineral supplements, respectively. Among screenees, response rates for the DHQ and the PLCO FFQ were 84% and 89%, respectively, and analyses of questions on portion size and supplement use showed few differences. These data indicated that the shorter FFQ was not better from the perspective of response rate and data quality, and that clarity and ease of administration may compensate for questionnaire length.
在本研究中，作者试图确定问卷长度和清晰度对两种食物频率问卷（FFQ）的应答率和数据质量的影响。这两种问卷分别是：新开发的36页饮食史问卷（DHQ），其设计目的是让受访者在认知上更容易填写；以及先前为前列腺、肺、结肠和卵巢（PLCO）癌筛查试验开发的16页FFQ。PLCO试验是一项始于1992年的为期23年的随机对照临床试验。这项子研究于1998年1月至4月进行，样本包括900名对照者和450名年龄在55 - 74岁之间的PLCO筛查参与者。对照者通过邮件收到DHQ或PLCO FFQ。筛查者在基线时已完成PLCO FFQ，此次接受DHQ。在对照者中，两种FFQ的应答率均为82%。对照者完成DHQ和PLCO FFQ所需的平均时间分别为68分钟和39分钟。对于摄入频率问题，两种问卷中缺失或无法解释的回答百分比相似，但对于分量大小和维生素/矿物质补充剂使用问题，DHQ中的百分比分别低约3和9个百分点（p≤0.001）。在筛查者中，DHQ和PLCO FFQ的应答率分别为84%和89%，对分量大小和补充剂使用问题的分析显示差异不大。这些数据表明，从应答率和数据质量的角度来看，较短的FFQ并非更好，而且清晰度和易于填写可能会弥补问卷长度的不足。
