Changes in physical functioning and quality of life in patients with cancer: response shift and relative evaluation of one's condition.

This study examined the hypothesis that patients' persistence in comparing themselves with others who are perceived as being worse off might induce a response shift in self-reported quality of life (QL). Specifically, we tested whether patients' ratings of how they are doing compared to others (i.e., relative evaluation) moderates the link between physical deterioration and decline in self-reported QL. Two hundred forty patients with various cancer diagnoses who were undergoing palliative chemotherapy rated their physical functioning and QL (i.e., emotional functioning and global quality of life) twice with an interval of 3 months. In addition, a significant other and a research assistant rated the physical condition of the patients. Consistent with the buffering model of response shift, patients who felt that they were better off than others appeared to be able to sustain their quality of life in the face of a worsening physical condition. In contrast, those who felt the same or worse off than others could not.