Validation of a condition-specific measure for women having an abnormal screening mammography

Objectives: The aim of this study is to assess the validity of a new condition-specific instrument measuring psychosocial consequences of abnormal screening mammography (PCQ-DK33). Methods: The draft version of the PCQ-DK33 was completed on two occasions by 184 women who had received an abnormal screening mammography and on one occasion by 240 women who had received a normal screening result. Item Response Theories and Classical Test Theories were used to analyze data. Construct validity, concurrent validity, known group validity, objectivity and reliability were established by item analysis examining the fit between item responses and Rasch models. Results: Six dimensions covering anxiety, behavioral impact, sense of dejection, impact on steep, breast examination, and sexuality were identified. One item belonging to the dejection dimension had uniform differential item functioning. Two items not fitting the Rasch models were retained because of high face validity. A sick leave item added useful information when measuring side effects and socioeconomic consequences of breast cancer screening. Five "poor items" were identified and should be deleted from the final instrument. Conclusions: Preliminary evidence for a valid and reliable condition-specific measure for women having an abnormal screening mammography was established. The measure includes 27 "good" items measuring different attributes of the same overall latent structure-the psychosocial consequences of abnormal screening mammography.