There is growing consensus that health-related quality of life (HRQL) outcomes are important for the allocation of scarce medical resources and for facilitating clinical decision-making. However, because most instruments of HRQL are self-report measures inappropriate conclusions may be drawn from studies that assess changes in HRQL over time or between groups. If the individuals evaluating themselves experience a response shift (defined as changes in their internalized standard of evaluating their level of functioning, in their values, or in their conceptualization of the target construct), then measures taken over time or between groups are no longer comparable. To date, response shift has not been formally assessed in the stroke population, and only to a limited extent in the HRQL field. The global objective of this thesis was to examine how the experience of recovering from a stroke modifies people's perception of their health-related quality of life (HRQL), and the extent to which response shift occurs during the first six months post-stroke. / The first study used structural equation modeling for data from a prospective cohort to evaluate response shift by examining changes in a theoretical model of HRQL based on the measurement model of the Medical Outcome Study 36-Item Short Form Health Survey (SF-36). This study found no evidence of reconceptualization and changes in internal standards over time, but suggested that if response shift does occur with stroke it is likely to be mediated by the event itself and not the recovery process. Two subsequent studies evaluated response shift using the then test (a retrospective assessment of HRQL) and an individualized measure of HRQL. The data collection for these studies was incorporated into a randomized controlled trial. The results from the then test provided support for the occurrence of response shift among persons with stroke with no such effect in a control group. Changes on the individualized measure of HRQL showed that individuals with stroke experienced a reconceptualization and a change in values between 6 and 24-weeks post-stroke. A final comparison of the three techniques evaluated in this thesis provided the basis for proposed guidelines for future assessments of change in HRQL based on the comparative feasibility and validity of the methods. To date, there is evidence to show that individuals undergoing changes in physical health experience changes in internal standards of health and values. If response shift is not measured and accounted for, inappropriate conclusions regarding the impact of a disease such as stroke or the efficacy of a treatment intervention may go unnoticed.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.84979 |
| Date | January 2004 |
| Creators | Ahmed, Sara, 1974- |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Epidemiology and Biostatistics.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 002166460, proquestno: AAINR06264, Theses scanned by UMI/ProQuest. |
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