Comparison of distribution- and anchor-based approaches to infer changes in health-related quality of life of prostate cancer survivors

Health Serv Res. 2012 Oct;47(5):1902-25. doi: 10.1111/j.1475-6773.2012.01395.x. Epub 2012 Mar 14.


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.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Cross-Sectional Studies
  • Humans
  • Linear Models
  • Longitudinal Studies
  • Male
  • Middle Aged
  • Outcome and Process Assessment, Health Care / methods
  • Prostatic Neoplasms / psychology
  • Prostatic Neoplasms / rehabilitation
  • Prostatic Neoplasms / therapy*
  • Quality Indicators, Health Care
  • Quality of Health Care
  • Quality of Life*
  • Survivors / psychology
  • Survivors / statistics & numerical data