Psychometric properties of a Swedish version of the Consequences of Screening--Breast Cancer questionnaire.

Aim: To evaluate the psychometric properties of a questionnaire addressing psychosocial consequences of false-positive mammographic screening.

Background: The Consequences of Screening--Breast Cancer and Lung Cancer questionnaires target psychosocial consequences of false-positive cancer screening. The Consequences of Screening--Breast Cancer questionnaire and ten items not considered lung cancer specific from the Lung Cancer questionnaire have been adapted for use in mammographic screening in Sweden, but remain psychometrically untested.

Design: Instrument development paper with psychometric cross-sectional and test-retest design.

Methods: Twelve scales of a Swedish questionnaire version were tested by the Rasch model and traditional psychometric methods. Women with false-positive (Group I, n = 640) and negative (Group II, n = 802) screening mammography responded to the study questionnaire and the Nottingham Health Profile during 2009-2011.

Results: Iterative analyses resulted in nine scales demonstrating Rasch model fit, but all scales exhibited poor targeting with relatively large floor effects. Corrected item-total correlations exceeded the recommended criterion. Score differences between Groups I and II and correlations with Nottingham Health Profile sections followed an expected pattern. Cronbach's α and test-retest reliability was acceptable for group-level assessments for ten and seven scales, respectively.

Conclusions: Five scales (Sense of dejection, Anxiety, Behavioural, Sleep and Existential values) of the Swedish questionnaire version demonstrated the best psychometric properties. Other scales should be used more cautiously. Although filling an important gap, causes of concern were identified across scales. The questionnaire should therefore be considered for group-level assessments rather than for measurement of individual degrees of psychosocial consequences.