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Estimating clinically significant differences in quality of life outcomes

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Abstract

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.

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Abbreviations

CTT:

classical test theory

MID:

minimal important difference

NNT:

number needed to treat

QOL:

quality of life

SEM:

standard error of measurement

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Correspondence to Kathleen W. Wyrwich.

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The Clinical Significance Consensus Meeting Group - See listing of members at the end of this article

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Wyrwich, K.W., Bullinger, M., Aaronson, N. et al. Estimating clinically significant differences in quality of life outcomes. Qual Life Res 14, 285–295 (2005). https://doi.org/10.1007/s11136-004-0705-2

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