Comparison of Distribution- and Anchor-Based Approaches to Infer Changes in Health-Related Quality of Life of Prostate Cancer Survivors
Article first published online: 14 MAR 2012
© Health Research and Educational Trust
Health Services Research
Volume 47, Issue 5, pages 1902–1925, October 2012
How to Cite
Jayadevappa, R., Malkowicz, S. B., Wittink, M., Wein, A. J. and Chhatre, S. (2012), Comparison of Distribution- and Anchor-Based Approaches to Infer Changes in Health-Related Quality of Life of Prostate Cancer Survivors. Health Services Research, 47: 1902–1925. doi: 10.1111/j.1475-6773.2012.01395.x
- Issue published online: 17 SEP 2012
- Article first published online: 14 MAR 2012
- DOD Prostate Cancer Research Program. Grant Numbers: DAMD17-02-1-0126, W81XWH-04-1-0257
- Linda and Laddie Montague Research Fund
- Prostate cancer;
- health-related quality of life;
- minimal important difference;
- anchor based;
- distribution based
To determine the minimal important difference (MID) in generic and prostate-specific health-related quality of life (HRQoL) using distribution- and anchor-based methods.
Study Design and Setting
Prospective cohort study of 602 newly diagnosed prostate cancer patients recruited from an urban academic hospital and a Veterans Administration hospital. Participants completed generic (SF-36) and prostate-specific HRQoL surveys at baseline and at 3, 6, 12, and 24 months posttreatment. Anchor-based and distribution-based methods were used to develop MID estimates. We compared the proportion of participants returning to baseline based on MID estimates from the two methods.
MID estimates derived from combining distribution- and anchor-based methods for the SF-36 subscales are physical function = 7, role physical = 14, role emotional = 12, vitality = 9, mental health = 6, social function = 9, bodily pain = 9, and general health = 8; and for the prostate-specific scales are urinary function = 8, bowel function = 7, sexual function = 8, urinary bother = 9, bowel bother = 8, and sexual bother = 11. Proportions of participants returning to baseline values corresponding to MID estimates from the two methods were comparable.
This is the first study to assess the MID for generic and prostate-specific HRQoL using anchor-based and distribution-based methods. Although variation exists in the MID estimates derived from these two methods, the recovery patterns corresponding to these estimates were comparable.