Impact of Response Shift on Time to Deterioration in Quality of Life Scores in Breast Cancer Patients
BACKGROUND
This prospective multicenter study aimed to study the impact of the recalibration component of response-shift (RS) on time to deterioration (TTD) in health related quality of life (QoL) scores in breast cancer (BC) patients and the influence of baseline QoL expectations on TTD.


METHODS
The EORTC-QLQ-C30 and BR-23 questionnaires were used to assess the QoL in a prospective multicenter study at inclusion (T0), at the end of the first hospitalization (T1) and, three (T2) and 6 months after the first hospitalization (T3). Recalibration was investigated by the then-test method. QoL expectancy was assessed at diagnosis. Deterioration was defined as a 5-point decrease in QoL scores, considered a minimal clinically important difference (MCID). TTD was estimated using the Kaplan-Meier method. Cox regression analyses were used to identify factors influencing TTD.


RESULTS
From February 2006 to February 2008, 381 women were included. Recalibration of breast cancer patients' internal standards in the assessment of their QoL had an impact on TTD. Median TTD were significantly shorter when recalibration was not taken into account than when recalibration was taken into account for global health, role-functioning, social-functioning, body-image and side effects of systemic therapy. Cox multivariate analyses showed that for body image, when recalibration was taken into account, radiotherapy was associated with a shorter TTD (HR: 0.60[0.38-0.94], whereas, no significant impact of surgery type on TTD was observed. For global health, cognitive and social functioning dimensions, patients expecting a deterioration in their QoL at baseline had a significantly shorter TTD.


CONCLUSIONS
Our results showed that RS and baseline QoL expectations were associated with time to deterioration in breast cancer patients.