Adaptation to Swedish and further development of the 'Consequences of Screening - Breast Cancer' questionnaire: a multimethod study.

Rationale: Experiencing a false-positive screening mammography can cause considerable psychosocial distress. The Consequences of Screening - Breast Cancer questionnaire (COS-BC parts 1 and 2), recently developed in Denmark, is the only condition-specific questionnaire for measuring short- and long-term psychosocial consequences of false-positive mammographic screening. Additional studies are needed to further test the COS-BC before use across cultures. Furthermore, studies have suggested that the consequences of false-positive screening results are partly common across cancer screening settings, although this hypothesis remains largely untested.

Objectives: This study (i) assesses content validity of a Swedish version of the COS-BC, (ii) tests whether items expressing long-term consequences of false-positive lung cancer screening results are relevant in a breast cancer screening context and (iii) explores the usefulness of taking results from Rasch analyses of the source version as an aid in questionnaire translation and adaptation.

Methods: Following dual-panel translation, content validity was assessed through qualitative interviews with representatives of the target population and the content validity index (CVI). Item locations and Rasch model fit of the source questionnaires were considered in the translation and assessment process.

Results: The COS-BC items were generally found relevant and provided coverage of the target construct. Content validity was supported also for nine of 10 lung cancer screening items. Scale CVI values were ≥0.81. Previous Rasch data were useful in facilitating translation and assessing item content validity. The resulting Swedish version of the COS-BC parts 1 and 2 consists of 34 and 23 items, respectively.

Conclusion: This study illustrates the value of methodological triangulation and use of data from previous Rasch analyses in questionnaire translation and adaptation. We found support for the hypothesis that consequences of false-positive screening are common across cancer screening settings. Psychometric properties of the Swedish COS-BC remain to be established.