Development and Psychometric Validation of BREAST-Q Scales Measuring Cancer Worry, Fatigue, and Impact on Work.

Abstract

The BREAST-Q is a patient-reported outcome measure for women with breast cancer. The aim of this study was to develop new BREAST-Q scales to measure Cancer Worry, Fatigue and Impact on Work. Data were collected between January 2017 and November 2019. Phase 1 (qualitative) included participants from Canada and the USA, pre/post any type of breast cancer treatment (surgery, adjuvant, neoadjuvant). Interviews were audio-recorded, transcribed verbatim and coded line-by-line. New scales were drafted and refined through cognitive interviews and expert input. Phase 2 (field-test study) involved USA members of the Love Research Army (LRA). Rasch measurement theory analysis was used to examine reliability and validity. In phase 1, 57 women were interviewed. Three concepts were identified as important to the breast cancer experience that are not currently covered in the BREAST-Q and developed into scales, i.e., Cancer Worry, Fatigue and Impact on Work. Feedback from nine women and 23 experts was used to establish content validity. The scales were field-tested in the LRA sample (n=1680), of whom 1006 completed a test-retest. Reliability was >0.81 for the person separation index, >0.89 for Cronbach's alpha and >0.83 for interclass correlation coefficients. Lower scores on all three scales were significantly associated with being closer in time to diagnosis and having a higher cancer stage at diagnosis (p<0.001 on ANOVA). These new scales expand the BREAST-Q measurement system and provide a means to evaluate additional important outcomes for breast cancer patients in clinical care and research.