@Article{信息:doi 10.2196 / / jmir。1733，作者=“McCambridge, Jim和Kalaitzaki, Eleftheria和White, Ian R和Khadjesari, Zarnie和Murray, Elizabeth和Linke, Stuart和Thompson, Simon G和Godfrey, Christine和Wallace, Paul”，标题=“在线试验中问卷长度或相关性对损耗的影响:随机对照试验”，期刊=“J Med Internet Res”，年=“2011”，月=“11”，日=“18”，卷=“13”，数=“4”，页=“e96”，关键词=“损耗;保留;缺失的数据;响应率;酒精;背景:在线研究中影响回复率和流失率的因素研究有限。在线实验嵌套在基于网络的有害饮酒者干预评估的先导(研究1,n = 3780)和主要试验(研究2,n = 2667)阶段:减少饮酒随机对照试验(DYD-RCT)。目的:目的是确定在线试验中问卷长度和相关性的差异是否会影响随访损失。方法:采用随机对照试验设计。 All participants who consented to enter DYD-RCT and completed the primary outcome questionnaires were randomized to complete one of four secondary outcome questionnaires at baseline and at follow-up. These questionnaires varied in length (additional 23 or 34 versus 10 items) and relevance (alcohol problems versus mental health). The outcome measure was the proportion of participants who completed follow-up at each of two follow-up intervals: study 1 after 1 and 3 months and study 2 after 3 and 12 months. Results: At all four follow-up intervals there were no significant effects of additional questionnaire length on follow-up. Randomization to the less relevant questionnaire resulted in significantly lower rates of follow-up in two of the four assessments made (absolute difference of 4{\%}, 95{\%} confidence interval [CI] 0{\%}-8{\%}, in both study 1 after 1 month and in study 2 after 12 months). A post hoc pooled analysis across all four follow-up intervals found this effect of marginal statistical significance (unadjusted difference, 3{\%}, range 1{\%}-5{\%}, P = .01; difference adjusted for prespecified covariates, 3{\%}, range 0{\%}-5{\%}, P = .05). Conclusions: Apparently minor differences in study design decisions may have a measurable impact on attrition in trials. Further investigation is warranted of the impact of the relevance of outcome measures on follow-up rates and, more broadly, of the consequences of what we ask participants to do when we invite them to take part in research studies. Trial registration: ISRCTN Register 31070347; http://www.controlled-trials.com/ISRCTN31070347/31070347 Archived by WebCite at (http://www.webcitation.org/62cpeyYaY) ", issn="1438-8871", doi="10.2196/jmir.1733", url="//www.mybigtv.com/2011/4/e96/", url="https://doi.org/10.2196/jmir.1733", url="http://www.ncbi.nlm.nih.gov/pubmed/22100793" }