Purpose: We still don't understand how cancer patients perceive their quality of life (QL) over time. Indeed, there is ample evidence of paradoxical findings in the literature. For exarnple, patients with cancer were found to report a stable QL over time, or a level of QL that is not inferior to that of healthy people. One possible explanation of such findings is 'response shift', which refers to changes in internal standards, values, and the definition of life quality (concept redefinition). The primary objective of the current study is to examine the extent to which and under which conditions, response shift occurs and contributies to the explanation of QL.
This objective will be examined with a theoretical model that includes five major components: (a) a catalyst, referring to a cancer diagnosis and invasive surgery; (b) antecedents, pertaining to sociodemographics, optimism and mastery; (c) mechanisms, including coping and social comparisons; (d) response shift, defined as changes in internal standards and values, and concept redefinition; and (e) perceived QL, encompassing functioning, symptoms, fatigue, and positive affect.
The research questions are: (1) To what extent does response shift occur among cancer patients undergoing invasive surgery; (2) To what extent do the catalyst, antecedents, and mechanisms affect the occurrence of response shift; (3) To what extent does the detected level of response shift contribute to perceived quality of life; and (4) To what extent is this model dependent on the moment in the disease trajectory?
Plan of investigation: The study sample will be composed of 240 newly diagnosed cervical, pancreatic, oesophageal, and lung cancer patients undergoing invasive surgery. Patients will be assessed at three points in time: prior to surgery, and three and nine months following surgery. At these sessions, patients will be asked to complete standardised QL measures. To assess changes in internal standards, patients will complete these QL measures at follow-up conventionally and in reference to how they perceive themselves to have been prior to surgery (a so-called 'thentest'). Changes in values and concept redefinition will be assessed by means of a card sort method, administered at three points in time, where patients are asked to order elicited and preset QL domains according to their perceived importance. At the two follow-up assessments, patients will additionally complete a situation-specific card-sort measure on coping, and standardised measures on optimism, mastery and social comparisons. Sociodemographic and clinical data will additionally be collected.
Possible results: This study will contribute to our understanding of how cancer patients perceive their QL over time when confronted with an invasive treatment. By explicitly measuring changes in internal standards, values and concept redefinition, we will be better able to assess adequately changes in perceived QL. By additionally examining the conditions under which such response shift effects occur, we will provide more insight into the accomodation processes of patients to deteriorating health. If response shift is demonstrated to be a viable concept, its inclusion in existing theoretical models and empirical study designs is recommended in a wide range of settings addressing changes in perceived QL. |
