Prostate cancer patients’ quality of life assessments across the primary treatment trajectory: ‘True’ change or response shift?

Abstract

Background Self-report questionnaires are widely used to assess changes in quality of life (QoL) during the course of cancer treatment. However, comparing baseline scores to follow-up scores is only justified if patients' internal measurement standards have not changed over time, that is, no response shift occurred. We aimed to examine response shift in terms of reconceptualization, reprioritization and recalibration among prostate cancer patients. Material and methods We included 402 newly diagnosed patients (mean age 65 years) and assessed QoL at the beginning of cancer treatment and three months later. QoL was measured with the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30). We employed structural equation modeling testing measurement invariance between occasions to disentangle 'true' change and change in the measurement model (response shift). Results We found reprioritization effects for both the Physical Functioning and Role Functioning subscales of the EORTC QLQ-C30, indicating that both had gained importance for representing the latent construct of QoL at follow-up. These effects added to the worsening effect evident in the latent construct, thus rendering observed changes even more pronounced. In addition, we found recalibration effects for both the Emotional Functioning and Cognitive Functioning subscales indicating judgments becoming more lenient over time. These effects counteracted 'true' negative changes thus obscuring any substantial changes on the observed level. Conclusion Our results suggest that changes observed in some subscales of the EORTC QLQ-C30 should not be taken at face value as they may be affected by patients' changed measurement standards.

Identifying patterns of adaptation in breast cancer patients with cancer‐related fatigue using response shift analyses at subgroup level

“…In the 1st, 3rd and 4th LC, reprioritization RS was detected in the physical fatigue domain which became less indicative of the latent construct of fatigue at month 8 compared to baseline whereas it went in the opposite direction in LC2. Reprioritization RS was also observed in other studies focusing on QoL in prostate and breast cancer patients where change in priorities and importance given to social or physical domains were evidenced over time as being more or less indicative of QoL or subjective well‐being.…”

Is there a response shift in generic health-related quality of life 6 months after glioma surgery?

“…Even though response shift is known to occur in cancer patients [8, 9, 17, 18], we have not found response-shift studies in glioma patients. Searching for clinically relevant subgroups that could exhibit response shift is also indicated.…”

“…recalibration, reprioritisation and reconceptualisation). In a recent study of patients with prostate cancer, reconceptualisation was not an important factor, perhaps indicating that the other two are more important elements in response shift among cancer patients [8]. Others consider the elements of reprioritisation and reconceptualisation not to be a true response shift, but rather coping strategies affecting the true value [3].…”

“…Response shift refers to the phenomenon where patients score better because over time they adapt to a new situation; for instance, a handicap or an illness [17, 18]. It is considered to involve elements of recalibration of internal standards, change in priorities and/or a different view upon the concept of HRQoL [3, 8, 27]. In patients with gliomas all these elements may change when faced with neurological deficits or being diagnosed with a life-threatening illness [18].…”

Response shift effects of quality of life assessments in breast cancer survivors

“…Based on a recent response shift study with the EORTC QLQ‐C30, SEM was applied to the functioning scales of the EORTC QLQ‐C30. Correlations between the error terms of physical and role functioning and between role and social functioning were allowed according to Gerlich et al () (Figure ). We used the maximum likelihood procedure as the estimation method for SEM models.…”