Quality of Life Research

, Volume 14, Issue 6, pp 1523–1532 | Cite as

Comparison of the minimally important difference for two health state utility measures: EQ-5D and SF-6D

  • Stephen J. Walters
  • John E. Brazier


Background: The SF-6D and EQ-5D are both preference-based measures of health. Empirical work is required to determine what the smallest change is in utility scores that can be regarded as important and whether this change in utility value is constant across measures and conditions. Objectives: To use distribution and anchor-based methods to determine and compare the minimally important difference (MID) for the SF-6D and EQ-5D for various datasets. Methods: The SF-6D is scored on a 0.29–1.00 scale and the EQ-5D on a −0.59–1.00 scale, with a score of 1.00 on both, indicating ‘full health’. Patients were followed for a period of time, then asked, using question 2 of the SF-36 as our anchor, if their general health is much better (5), somewhat better (4), stayed the same (3), somewhat worse (2) or much worse (1) compared to the last time they were assessed. We considered patients whose global rating score was 4 or 2 as having experienced some change equivalent to the MID. This paper describes and compares the MID and standardised response mean (SRM) for the SF-6D and EQ-5D from eight longitudinal studies in 11 patient groups that used both instruments. Results: From the 11 reviewed studies, the MID for the SF-6D ranged from 0.011 to 0.097, mean 0.041. The corresponding SRMs ranged from 0.12 to 0.87, mean 0.39 and were mainly in the ‘small to moderate’ range using Cohen’s criteria, supporting the MID results. The mean MID for the EQ-5D was 0.074 (range −0.011–0.140) and the SRMs ranged from −0.05 to 0.43, mean 0.24. The mean MID for the EQ-5D was almost double that of the mean MID for the SF-6D. Conclusions: There is evidence that the MID for these two utility measures are not equal and differ in absolute values. The EQ-5D scale has approximately twice the range of the SF-6D scale. Therefore, the estimates of the MID for each scale appear to be proportionally equivalent in the context of the range of utility scores for each scale. Further empirical work is required to see whether or not this holds true for other utility measures, patient groups and populations.


EQ-5D Minimum important difference Preference-based measures SF-6D Utility 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Sloan, JA, Cella, D, Frost, M,  et al. 2002Assessing clinical significance in measuring oncology patient quality of life: Introduction to the symposium, content overview, and definition of termsMayo Clin Proc.77367370PubMedGoogle Scholar
  2. 2.
    Guyatt, GH, Osoba, D, Wu, AW, Wyrwich, KW, Norman, GR. 2002Clinical Significance Consensus Meeting Group. Methods to explain the clinical significance of health status measuresMayo Clin Proc.77371383PubMedGoogle Scholar
  3. 3.
    Cella, D, Bullinger, M, Scott, C, Barofsky, I. 2002Clinical Significance Consensus Meting Group. Group vs. individual approaches to understanding the clinical significance of differences or changes in quality of life.Mayo Clin Proc.77384392PubMedGoogle Scholar
  4. 4.
    Sloan, JA, Aaronson, N, Cappelleri, JC, Fairclough, DL, Varricchio, C. 2002Clinical Significance Consensus Meeting Group. Assessing the clinical significance of single items relative to summated scores.Mayo Clin Proc.77479487PubMedGoogle Scholar
  5. 5.
    Frost, MH, Bonomi, AE, Ferrans, CE, Wong, GY, Hays, RD. 2002Clinical Significance Consensus Meeting Group. Patient, clinician, and population perspectives on determining the clinical significance of quality-of-life scores.Mayo Clin Proc.77488494PubMedGoogle Scholar
  6. 6.
    Sprangers, MA, Moinpour, CM, Moynihan, TJ, Patrick, DL, Revicki, DA. 2002Clinical Significance Consensus Meeting Group Assessing meaningful change in quality of life over time: A users’ guide for clinicians.Mayo Clin Proc.77561571PubMedGoogle Scholar
  7. 7.
    Symonds, T, Berzon, R, Marquis, P, Rummans, TA. 2002Clinical Significance Consensus Meeting Group. The clinical significance of quality-of-life results: Practical considerations for specific audiences.Mayo Clin Proc.77572583PubMedGoogle Scholar
  8. 8.
    Fayers, PM, Machin, DM. 2000Quality of Life: Assessment, Analysis & InterpretationWileyChichester.Google Scholar
  9. 9.
    Jaeschke, R, Singer, J, Guyatt, GH. 1989Measurement of health status. Ascertaining the minimal clinically important difference.Contr Clin Trials.10407415CrossRefGoogle Scholar
  10. 10.
    Sloan, J, Symonds, T, Vargas-Chanes, D, Fridley, B. 2003Practical guidelines for assessing the clinical significance of health-related quality of life changes within clinical trialsDrug Inf J.372331Google Scholar
  11. 11.
    Juniper, EF, Guyatt, GH, Willan, A, Griffith, LE. 1994Determining a minimal important change in a disease-specific Quality of Life questionnaireJ Clin Epidemiol.478187CrossRefPubMedGoogle Scholar
  12. 12.
    Norman, GR, Sridhar, FG, Guyatt, GH, Walter, SD. 2001The relation of distribution- and anchor-based approaches in interpretation of changes in health related quality of lifeMed Care.3910391047CrossRefPubMedGoogle Scholar
  13. 13.
    Cohen, J. 1988Statistical Power Analysis for the Behavioural Sciences.2Lawrence ErlbaumMahwah, NJGoogle Scholar
  14. 14.
    Norman, GR, Stratford, P, Regehr, G. 1997Methodological problems in the retrospective computation of responsiveness to change: The lesson of CronbachJ Clin Epidemiol.50869879PubMedGoogle Scholar
  15. 15.
    Brazier, JE, Roberts, JF, Deverill, MD. 2002The estimation of a preference based measure of health from the SF-36Health Econ.21271292Google Scholar
  16. 16.
    Dolan P, Gudex C, Kind P, Williams A. A social tariff for the EuroQol: Results from a UK general population survey. Centre for Health Economics Discussion Paper No. 138. York: University of York, 1995Google Scholar
  17. 17.
    Ware, JE,Jr, Snow, KK, Kosinski, M, Gandek, B. 1993SF-36 Health Survey Manual and Interpretation GuideThe Health Institute, New England Medical CentreBoston, MAGoogle Scholar
  18. 18.
    Walters, SJ, Morrell, CJ, Dixon, S. 1999Measuring health-related quality of life in patients with venous leg ulcersQual Life Res.8327336PubMedGoogle Scholar
  19. 19.
    Thomas, KJ, MacPherson, H, Thorpe, L,  et al. 2003Longer term clinical and economic benefits of offering acupuncture to patients with chronic low back pain. Report to NCCHTASchARR, University of SheffieldSheffield, UKGoogle Scholar
  20. 20.
    Allard, S. 2000NAME IT Study Group. Phase IIIB. IV Clinical Study Report of a Double-Blind, Randomised, Controlled Study to Compare Methotrexate plus Neoral® versus Methotrexate plus Placebo in Subjects with Early Severe Rheumatoid ArthritisNovartis PharmaBasel, SwitzerlandGoogle Scholar
  21. 21.
    Burton, M, Walters, S, Saleh, M, Brazier, J. 2003An Evaluation of Health Status Measures in Lower Limb Trauma. Report for Trent Regional Health AuthorityUniversity of SheffieldSheffield, UKGoogle Scholar
  22. 22.
    Akehurst, RL, Brazier, JE, Mathers, N, et al.,  2002Health-related quality of life and cost impact of irritable bowel syndrome in a UK primary care settingPharmacoeconomics.20455462PubMedGoogle Scholar
  23. 23.
    Lacey, EA, Walters, SJ. 2003Continuing inequality: Gender and social class influences on self-perceived health after a heart attackJ Epidemiol Commun Health.57622627Google Scholar
  24. 24.
    Brazier, JE, Harper, R, Munro, JF, Walters, SJ, Snaith, ML. 1999Generic and condition-specific outcome measures for people with osteoarthritis of the kneeRheumathology.38870877Google Scholar
  25. 25.
    Harper, R, Brazier, JE, Waterhouse, JC, Walters, SJ, Jones, NMB, Howard, P. 1997Comparison of outcome measures for patients with chronic obstructive pulmonary disease (COPD) in an outpatient settingThorax.52879887PubMedGoogle Scholar
  26. 26.
    Kazis, LE, Anderson, JJ, Meenan, RF. 1989Effect sizes for interpreting changes in health statusMed Care.27S178S189PubMedGoogle Scholar
  27. 27.
    Liang, MH, Fossel, AH, Larson, MG. 1990Comparisons of Five Health Status Instruments for Orthopaedic EvaluationMed Care.28632642PubMedGoogle Scholar
  28. 28.
    Norman, GR, Sloan, JA, Wyrwich, KW. 2003Interpretation of changes in health related quality of life: The remarkable universality of half a standard deviationMed Care.41582592PubMedGoogle Scholar
  29. 29.
    Ryan, M, Scott, DA, Reeves, C, Bate, A, Teijlingen, ER, Russell, EM, Napper, M, Robb, CM. 2001Eliciting public preferences for healthcare: A systematic review of techniquesHealth Technol Assess.51186Google Scholar
  30. 30.
    Brazier, J, Deverill, M, Green, C, Harper, R, Booth, A. 1999A review of the use of health status measures in economic evaluationHealth Technol Assess.31164Google Scholar
  31. 31.
    Wyrwich, KW, Metz, SM, Babu, AN, Kroenke, K, Tierney, WM, Wolinsky, FD. 2002The reliability of retrospective change assessmentsQual Life Res.11636Google Scholar
  32. 32.
    Walters, SJ, Brazier, JE. 2003What is the relationship between the minimally important difference and health state utility values? The case of the SF-6DHealth Qual Life Outcomes.118PubMedGoogle Scholar
  33. 33.
    Perneger, TV. 1998What’s wrong with Bonferroni adjustmentsBr Med J.31612361238Google Scholar
  34. 34.
    Fairclough, DL. 2002Design and Analysis of Quality of Life Studies in Clinical TrialsChapman & HallNew YorkGoogle Scholar
  35. 35.
    Jacobson, NS, Truax, P. 1991Clinical significance: A statistical approach to defining meaningful change in psychotherapy researchJ Consult Clin Psychol.591219PubMedGoogle Scholar
  36. 36.
    Fergason, RJ, Robinson, AB, Spaine, M. 2002Use of the reliable change index to evaluate clinical significance in SF-36 outcomesQual Life Res11509516CrossRefPubMedGoogle Scholar
  37. 37.
    Wyrwich, KW, Nienaber, NA, Tierney, WM, Wolinsky, FD. 1999Linking clinical relevance and statistical significance in evaluating intra-individual changes in health-related quality of lifeMed Care.37469478PubMedGoogle Scholar
  38. 38.
    Wyrwich, KW, Tierney, WM, Wolinsky, FD. 2002Using the standard error of measurement to identify important changes on the asthma quality of life questionnaireQual Life Res.1117PubMedGoogle Scholar
  39. 39.
    Drummond, MF. 2001Introducing economic and quality of life measures into clinical studiesAnn Med.33344349PubMedGoogle Scholar
  40. 40.
    Walters, SJ, Campbell, MJ, Paisley, S. 2001Methods for determining sample sizes for studies involving quality of life measures: A tutorialHealth Services Outcomes Res Methodol.28399Google Scholar

Copyright information

© Springer 2005

Authors and Affiliations

  1. 1.Health Economics and Decision Science, School of Health and Related ResearchUniversity of SheffieldSheffieldUK

Personalised recommendations