Harms of colorectal cancer (CRC) screening include psychosocial consequences. We have not identified studies using a participant-relevant questionnaire with adequate measurement properties to investigate these harms. However, Brodersen et al. have previously developed a core questionnaire consequences of screening (COS) for use in screening for life-threatening diseases. Therefore, the objectives were: (1) To investigate content validity of COS in a CRC screening setting and in case of gaps in content coverage (2) generate new items and themes and (3) test the possibly extended version of COS for dimensionality and differential item functioning (DIF) using Rasch Models. We performed two-part-focus-groups with CRC screenees. Screenees were recruited by strategic sampling. In the first part 16 screenees with false-positive results (n = 7) and low-risk polyps (n = 9) were interviewed about their CRC screening experiences and in the second part COS was examined for content validity. When new information was developed in the focus groups, new items covering this topic were generated. Subsequently, new items were, together with COS, tested in the subsequent interviews. A random subsample (n = 410) from a longitudinal questionnaire study, not yet published, was used to form the data for this paper. We analysed multidimensionality and uniform DIF with Andersen’s conditional likelihood ratio test. We assessed individual item fit to the model. We also analysed Local Dependence (LD) and DIF by partial gamma coefficients using Rasch Models. COS was found relevant in a CRC screening setting. However, new information was discovered in the focus groups, covered by 18 new CRC screening-specific items. The Rasch analyses only revealed minor problems in the COS-scales. The 18 new items were distributed on four new CRC screening-specific dimensions and one single item. An extended version of COS specifically for use in a CRC screening setting has been developed. The extended part encompasses four new scales and one new single item. The original COS with the CRC-screening specific extension is called consequences of screening in colorectal cancer (COS-CRC). COS-CRC possessed reliability, unidimensionality and invariant measurement.

中文翻译：

---

大肠癌筛查的后果（COS-CRC）：问卷的发展和维度

结肠直肠癌（CRC）筛查的危害包括社会心理后果。我们还没有使用与参与者相关的调查表来确定具有足够测量特性的调查这些危害的研究。但是，Brodersen等。先前已经开发了用于筛选威胁生命的疾病的核心筛查结果问卷（COS）。因此，目标是：（1）在CRC筛查环境中调查COS的内容有效性，并在内容覆盖范围出现空白的情况下（2）生成新项目和主题，以及（3）测试COS的可能扩展版本的维度和使用Rasch模型的差异项功能（DIF）。我们与CRC接受者进行了分为两部分的焦点小组讨论。通过战略抽样招募筛选者。在第一部分中，对16名筛查结果为假阳性（n = 7）和低危息肉（n = 9）的受检者进行了CRC筛查经验，在第二部分中，对COS的内容有效性进行了检查。在焦点组中开发新信息时，就生成了涉及该主题的新项目。随后，新项目与COS一起在随后的采访中进行了测试。来自纵向调查表研究的随机子样本（n = 410）尚未发表，用于形成本文的数据。我们使用安德森（Andersen）的条件似然比检验分析了多维和统一DIF。我们评估了适合模型的单个项目。我们还使用Rasch模型通过部分伽马系数分析了局部依赖性（LD）和DIF。发现COS与CRC筛查有关。然而，在焦点小组中发现了新信息，涵盖了18个针对CRC筛查的新项目。Rasch分析仅揭示了COS规模的小问题。18个新项目以四个新的CRC筛查特定维度和一个项目进行了分配。已经开发了专门用于CRC筛查设置的COS扩展版本。扩展部分包括四个新的音阶和一个新的单个项目。具有CRC筛查特异性扩展的原始COS被称为结肠直肠癌筛查的结果（COS-CRC）。COS-CRC具有可靠性，一维性和不变性。18个新项目以四个新的CRC筛查特定维度和一个项目进行了分配。已经开发了专门用于CRC筛查设置的COS扩展版本。扩展部分包括四个新的音阶和一个新的单个项目。具有CRC筛查特异性扩展的原始COS被称为结肠直肠癌筛查的结果（COS-CRC）。COS-CRC具有可靠性，一维性和不变性。18个新项目以四个新的CRC筛查特定维度和一个项目进行了分配。已经开发了专门用于CRC筛查设置的COS扩展版本。扩展部分包括四个新的音阶和一个新的单个项目。具有CRC筛查特异性扩展的原始COS被称为结肠直肠癌筛查的结果（COS-CRC）。COS-CRC具有可靠性，一维性和不变性。