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Comparison of Distribution- and Anchor-Based Approaches to Infer Changes in Health-Related Quality of Life of Prostate Cancer Survivors

Authors

  • Ravishankar Jayadevappa,

    Corresponding author
    • Division of Urology, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia Veterans Administration Medical Center, Perelman Center for Advanced Medicine, Philadelphia, PA
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  • Stanley Bruce Malkowicz,

    1. Division of Urology, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia Veterans Administration Medical Center, Perelman Center for Advanced Medicine, Philadelphia, PA
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  • Marsha Wittink,

    1. Department of Psychiatry, School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, NY
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  • Alan J. Wein,

    1. Division of Urology, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Perelman Center for Advanced Medicine, Philadelphia, PA
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  • Sumedha Chhatre

    1. Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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Address correspondence to Ravishankar Jayadevappa, Ph.D., Department of Medicine, Perelman School of Medicine, University of Pennsylvania, 224, Ralston-Penn Center, 3615 Chestnut Street, Philadelphia, PA 19104-2676; e-mail: jravi@mail.med.upenn.edu

Abstract

Objective

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.

Results

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.

Conclusions

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.

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