Estimating clinically significant differences in quality of life outcomes
Cite this article as: Wyrwich, K.W., Bullinger, M., Aaronson, N. et al. Qual Life Res (2005) 14: 285. doi:10.1007/s11136-004-0705-2 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. Keywords Clinically important change Clinical significance Minimally important difference Quality of life Abbreviations CTT
classical test theory
minimal important difference
number needed to treat
quality of life
standard error of measurement
The Clinical Significance Consensus Meeting Group - See listing of members at the end of this article
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