minimal clinically important differences mcid

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1. Minimal Clinically Important Differences (MCID)

3. Two Essential Elements 1. External (not HRQOL measure being evaluated) indicator of change (Anchor) 2. Amount of HRQOL change among those determined to have changed on anchor, relative to noise (variance).

5. Self-Report Anchor (A) Overall has there been any change in your asthma since the beginning of the study? Much improved; Moderately improved; Minimally improved No change Much worse; Moderately worse; Minimally worse

9. Magnitude of HRQOL Change Should Parallel Underlying Change

13. MID Varies by Anchor 693 RA clinical trial participants evaluated at baseline and 6-weeks post-treatment. Five anchors: 1) patient global self-report; 2) physician global report; 3) pain self-report; 4) joint swelling; 5) joint tenderness Kosinski, M. et al. (2000). Determining minimally important changes in generic and disease-specific health-related quality of life questionnaires in clinical trials of rheumatoid arthritis. Arthritis and Rheumatism, 43, 1478-1487.

14. Changes in SF-36 Scores Associatedwith Minimal Change in Anchors

15. Samsa et al. (1999, p. 149) said MID for SF-36 is “typically in the range of 3 to 5 points” (p. 149). {.09->0.28 ES} Samsa, G., Edelman, D., Rothman, M. L., Williams, G. R., Lipscomb, J., & Matchar, D. Pharmacoeconomics, 15, 141-155: 1999.

17. MID Varies by Starting Position Same retrospective report of change associated with bigger prospective change for those with more room to change Among those who said their physical health was somewhat worse, change ranged from –26 points to +3 points for people with high (81-100) versus low (0-20) baseline physical health (Baker et al., 1997, Medical Care).

18. Group Average is Different from Individual Change Average change collapses across individual responses. Is inference about minimum amount of change that is important for individuals based on a group average reasonable? What if scale score improved by 4 points for half the people and 0 points for the other half? Is the MID = 2 or 4?

19. Example Use of Self-Report Anchor in COPD Compared to Jack, my ability to walk is: Much better; Somewhat better; A little bit better; About the same; A little bit worse; Somewhat worse; Much worse Determined how much actual walking distance had to differ, on average, for patients to rate themselves as walking either a little bit better or “a little bit worse. Redelmeier, D. A. et al., 1997, Am J Respir Crit Care Med

20. Example with Multiple Anchors 693 RA clinical trial participants evaluated at baseline and 6-weeks post-treatment. Five anchors: 1) patient global self-report; 2) physician global report; 3) pain self-report; 4) joint swelling; 5) joint tenderness Kosinski, M. et al. (2000). Determining minimally important changes in generic and disease-specific health-related quality of life questionnaires in clinical trials of rheumatoid arthritis. Arthritis and Rheumatism, 43, 1478-1487.

21. Patient and Physician global reports How the patient is doing, considering all the ways that RA affects him/here? Very good (asymptomatic and no limitation of normal activities) Good (mild symptoms and no limitation of normal activities) Fair (moderate symptoms and limitation of normal activities) Poor (severe symptoms and inability to carry out most normal activities) Very poor (very severe symptoms that are intolerable and inability to carry out normal activities)

22. Pain self-report 10 centimeter visual analog scale 0 = no pain, 10 = severe pain

23. Threshold on Self-Report and Physician Report Anchors Used for MID estimation Patient and physician global reports Improvement of 1 level over time. Pain self-report Improvement of 1-20% over time.

24. Joint swelling and tenderness anchors Number of swollen and tender joints Threshold for MID estimation = 1-20% improvement over time

25. Recommendations Use multiple anchors Use anchors that represent minimal change Report average across anchors and studies, range, and SD Consider that it can be easier to conclude that a difference is clearly or obviously important than it is to say one is always unimportant (grey area).

26. Appendix: Terminology Minimally Important Difference (MID) Minimal difference (MD) Minimally Detectable Difference (MDD) Clinically Important Difference (CID)

27. Value Depends on Cost A small positive change has greater value if it costs less. Importance of HRQOL change depends on what it costs to produce it.

29. So How Big Are Different Changes? Effect size benchmarks Small: 0.20->0.49 Moderate: 0.50->0.79 Large: 0.80 or above

31. Example of Preference Approach National Emphysema Treatment Trial (NETT)

32. Subjects 606 male and 387 female participants in the National Emphysema Treatment Trial (NETT)

33. Exclusion Criteria characteristics that place them at high risk for peri-operative morbidity and/or mortality emphysema felt to be unsuitable for LVRS, and medical conditions or other circumstances that make it likely that the patient would be unable to complete the trial.

34. Measures: Pre-post rehabilitation, 12 months, 24 months Quality of Well being scale (QWB-SA) Medical Outcomes Study 36 Item Short Form (SF36) St. Georges’ Respiratory Questionnaire (SGRQ) UCSD Shortness of Breath Questionnaire (SOBQ).

35. NETT Survival Result: NEJM May 22, 2003

36. NETT Patients were randomly assigned to maximal medical therapy LVRS. Those assigned to LVRS video assisted thoracoscopy (VATS median sternotomy

37. Descriptive Statistics for Change Scores in Rehabilitation Phase of NETT

38. Change in QOL Measures by QWB change category

39. Change in SOBQ by QWB Catetory

40. Change in SGRQ by QWB Category

41. Change in SF-36 PCS by QWB Category

42. Change in SF-36 MCS by QWB Category

43. Cumulative Mean QALYs Per Person N refers to the number alive at the start of each time periodN refers to the number alive at the start of each time period

45. Comparison of Cost/QALY for Different Programs in COPD (2002 dollars)

46. Conclusions The preference scaling system in generic utility based quality of life measures provides a metric that is directly interpretable and avoids many of the criticisms of MCID measures Quality adjusted life years offer a valuable metric for policy analysis. Utility-based measures of health-quality of life should gain greater use in COPD outcomes research.

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