From breast-Q © to Q-score ©: Using rasch measurement to better capture breast surgery outcomes

The two aims of this study were: 1) to bring together Rasch measurement methods (RMMs) with substantive clinically-grounded hypotheses to develop measures of health-related quality of life and patient satisfaction for reconstructive and cosmetic breast surgery; and 2) develop an accessible scoring program to provide automated clinically interpretable scores, based on calibrated item locations. We constructed a new patient reported outcome (PRO) instrument (BREAST-Q ©) from patient interviews (n=48), focus groups (n=18), and expert opinion. It was then fieldtested in samples of breast surgery patients (n=1950 & n=817). Item generation led to three separate modules for different types of breast surgery, each with a pre- and postoperative version: 1) augmentation; 2) reconstruction; and 3) reduction. RMMs supported the summing of items to form a total score for all subscales, in each module. Based on these analyses the Q-Score © scoring algorithm program was developed, tested and finalised. The BREAST-Q © is an advance on the way PROs are currently measured and can provide essential information about the impact and effectiveness of breast surgery from the patients' perspective. The Q-Score © program enables the BREAST-Q © to be widely used and interpreted correctly, underpinned by an equivalent frame of reference across different clinical settings.