Consequences of screening in colorectal cancer (COS-CRC): development and dimensionality of a questionnaire

Abstract

Background 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. Methods 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. Results 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. Conclusion 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.

Short and long-term psychosocial consequences of participating in a colorectal cancer screening programme: a matched longitudinal study

“…The instrument used to measure psychosocial consequences was the consequences of screening for CRC questionnaire (COS-CRC). 24 The screening programme A population-based CRC screening programme was implemented in Denmark in 2014-2017, and targets all individuals aged 50-74 years with an FIT as the screening test (figure 1). 8 The programme was rolled out gradually in a method based on birth months: the months of the year were randomly distributed over the 4 years, and each year individuals from three birth months were invited to participate in the screening.…”

“…We used the condition-specific questionnaire COS-CRC to assess the psychosocial consequences. 24 COS-CRC is an extended version of the screening-specific questionnaire COS. 27 28 COS-CRC was developed in two phases: (1) in the first phase, we performed focus groups with CRC screening participants with no abnormalities and with LR polyp findings to ensure high content validity; (2) in the second phase, data collected in this study was used to validate the questionnaire statistically using item response theory and Rasch Models. 29 COS-CRC consists of three parts: part I that consists of nine scales and two single items and can be used at any time point in the screening cascade and in a group not invited to screening as well, part Ix that consists of four scales and one single item and is only relevant to participants that have undergone the follow-up colonoscopy and part II that consists of five scales, and measures long-term consequences of CRC screening.…”

“…The instrument used to measure psychosocial consequences was the consequences of screening for CRC questionnaire (COS-CRC). 24 …”

“…We used the condition-specific questionnaire COS-CRC to assess the psychosocial consequences. 24 COS-CRC is an extended version of the screening-specific questionnaire COS. 27 28 COS-CRC was developed in two phases: (1) in the first phase, we performed focus groups with CRC screening participants with no abnormalities and with LR polyp findings to ensure high content validity; (2) in the second phase, data collected in this study was used to validate the questionnaire statistically using item response theory and Rasch Models. 29…”

Psychosocial consequences of invitation to colorectal cancer screening: a matched cohort study

“…We used part one of the condition-specific questionnaire Consequences Of Screening in CRC (COS-CRC) to assess psychosocial consequences ( figure 1 ). 13 We used the nine scales and two single items of the COS-CRC that do not require that the respondents have been through the screening cascade. For all items, the response options are arranged in four categories from ‘Not at all’ to ‘A lot’ with corresponding scores 0–3 ( online supplemental appendix 3 ).…”