Response shift effects on measuring post-operative quality of life among breast cancer patients: a multicenter cohort study

To characterize response shift effects in patients with breast cancer (BC).

The QLQ-C30, BR23, and EurQOL-EQ-5D were assessed at baseline and at the end of the first hospitalization. We used the then-test
approach to characterize changes in internal standards by calculating the mean difference between the then-test (retrospective
measure) and pre-test baseline QoL assessments. The Ideal Scale Approach was also used to assess changes in standards by comparing
health and QoL expectancies between baseline and the end of the first hospitalization. Successive Comparison Approach was
used to assess changes in values through the longitudinal assessment of the relative importance of EuroQOL dimensions.

The results of this study showed that recalibration RS effects occurred early after the first hospitalization for 6/15 dimensions
of QLQ-C30 (emotional, cognitive, fatigue, insomnia, appetite loss, diarrhea) and 2/8 of BR-23 (future perspective, systemic
therapy side effects). Moreover, health and QoL expectancies changed between the baseline and the end of the first hospitalization,
and changes in values were seen for the self-care and usual activities dimensions of the EuroQOL-EQ-5D.

The occurrence of RS early after the first hospitalization suggests that it needs to be taken into account to interpret QoL
changes in BC.