Abstract
BACKGROUND: We previously reported that changes of 6-17 percent in the EORTC QLQ-C30 scores are considered important by patients with multiple myeloma and thus may be considered as Minimal Important Differences (MIDs). However, patients' internal standard of measurement may have changed over time (response shift, RS). In the present work, we evaluated whether myeloma patients experience RS and if this could affect the MID-estimates. METHODS: Between 2006 and 2008, 239 patients with multiple myeloma completed the EORTC QLQ-C30 at inclusion (T1) and after three months (T2). At T2, patients were asked if they had noticed any change in the domains pain, fatigue, physical function and global quality of life. They were also asked to give a retrospective judgment of their health-related quality of life at T1 for the four domains. RESULTS: We found clear evidence of RS in myeloma patients. However, there were differences in both magnitude and direction between patients who stated that they improved and those who deteriorated. Deteriorating patients retrospectively reported better health-related quality of life at T1 for the domains pain, fatigue and physical function. In these patients, MIDs adjusted for RS were observed to increase up to 12 percentage points. In contrast, for patients stating that they improved, we only found evidence of statistically significant RS in global quality of life. CONCLUSIONS: MIDs estimated from pre-test/post-test data appeared to be robust against RS in patients reporting improvement over 3-months. This could indicate that RS has a minimal impact on the results in patients who respond to treatment, and that RS may not have an important impact on interpretation of changes reported in clinical trials where an improvement occurs. Although the effect sizes of the RSs were small, RS in deteriorating patients may have an important impact on the interpretation of changes reported in clinical trials. Trial registration: The study is registered at clinicaltrials.gov, identifier NCT00290095.
| Original language | English |
|---|---|
| Article number | 79 |
| Number of pages | 8 |
| Journal | Health and Quality of Life Outcomes |
| Volume | 8 |
| Issue number | 1 |
| Early online date | 3 Aug 2010 |
| DOIs | |
| Publication status | Published - 3 Aug 2010 |
Bibliographical note
AcknowledgementsThis project has been financed with the aid of EXTRA funds from the Norwegian Foundation for Health and Rehabilitation. The authors thank health-care providers at the following hospitals for recruiting patients to this study: Akershus University Hospital; Diakonhjemmet Hospital; Lovisenberg Diaconal Hospital; Oslo University Hospital, Aker; Oslo University Hospital, Ulleval; Sorlandet Hospital, Arendal; Sykehuset in Vestfold, Tonsberg; Sykehuset Innlandet, division Gjovik, Hamar, Kongsvinger and Lillehammer; Sykehuset Ostfold, Fredrikstad; Telemark Hospital, Skien; Vestre Viken HF, division Asker and Baerum, Buskerud, Kongsberg and Ringerike.
Preliminary results have been presented as a paper at the ISOQOL annual meeting, New Orleans, October 2009
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- Minimal important differences and response shift in health-related quality of life; a longitudinal study in patients with multiple myeloma
© 2010 Kvam et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.