Quality of Life Research

, Volume 14, Issue 2, pp 285–295 | Cite as

Estimating clinically significant differences in quality of life outcomes

  • Kathleen W. Wyrwich
  • Monika Bullinger
  • Neil Aaronson
  • Ron D. Hays
  • Donald L. Patrick
  • Tara Symonds


Objective: This report extracts important considerations for determining and applying clinically significant differences in quality of life (QOL) measures from six published articles written by 30 international experts in the field of QOL assessment and evaluation. The original six articles were presented at the Symposium on Clinical Significance of Quality of Life Measures in Cancer Patients at the Mayo Clinic in April 2002 and subsequently were published in Mayo Clinic Proceedings. Principal findings: Specific examples and formulas are given for anchor-based methods, as well as distribution-based methods that correspond to known or relevant anchors to determine important differences in QOL measures. Important prerequisites for clinical significance associated with instrument selection, responsiveness, and the reporting of QOL trial results are provided. We also discuss estimating the number needed to treat (NNT) relative to clinically significant thresholds. Finally, we provide a rationale for applying group-derived standards to individual assessments. Conclusions: While no single method for determining clinical significance is unilaterally endorsed, the investigation and full reporting of multiple methods for establishing clinically significant change levels for a QOL measure, and greater direct involvement of clinicians in clinical significance studies are strongly encouraged.


Clinically important change Clinical significance Minimally important difference Quality of life 



classical test theory


minimal important difference


number needed to treat


quality of life


standard error of measurement


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Copyright information

© Springer 2005

Authors and Affiliations

  • Kathleen W. Wyrwich
    • 1
  • Monika Bullinger
    • 2
  • Neil Aaronson
    • 3
  • Ron D. Hays
    • 4
  • Donald L. Patrick
    • 5
  • Tara Symonds
    • 6
  1. 1.Saint Louis UniversitySt. LouisUSA
  2. 2.Department of Medical PsychologyUniversity Clinics EppendorfHamburgGermany
  3. 3.Division of Psychosocial ResearchThe Netherlands Cancer InstituteAmsterdamThe Netherlands
  4. 4.UCLA School of Medicine, RANDLos Angeles, Santa MonicaUSA
  5. 5.Departments of Health Services and EpidemiologyUniversity of WashingtonSeattleUSA
  6. 6.Outcomes Research DepartmentPfizer Ltd.KentUK

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