The Concept of Clinically Meaningful Difference in Health-Related Quality-of-Life Research
- 616 Downloads
It is generally believed that small differences in health-related quality of life (HR-QOL) may be statistically significant yet clinically unimportant. The concept of the minimal clinically meaningful difference (MCID) has been proposed to refer to the smallest difference in a HR-QOL score that is considered to be worthwhile or clinically important.
However, there is danger in oversimplification in asking the question: what is the MCID on this HR-QOL instrument? We argue that the attempt to define a single MCID is problematic for a number of reasons and recommend caution in the search for the MCID holy grail. Specifically, absolute thresholds are suspect because they ignore the cost or resources required to produce a change in HR-QOL. In addition, there are several practical problems in estimating the MCID, including: (i) the estimated magnitude varies depending on the distributional index and the external standard or anchor; (ii) the amount of change might depend on the direction of change; and (iii) the meaning of change depends on where you start (baseline value).
- 8.Cohen J. Statistical power analysis for the behavioral sciences. 2nd ed. London: Academic Press, 1988Google Scholar
- 11.Ware JE, Snow K, Kosinski M, et al. SF-36 Health Survey: manual and interpretation guide. Boston (MA): The Health Institute, 1993Google Scholar
- 13.Ware JE, Kosinski M, Keller SD. SF-36 physical and mental health summary scales: a user’s manual. Boston (MA): The Health Institute, 1994Google Scholar
- 14.Lansky D, Butler JB, Waller FT. Using health status measures in the hospital setting: from acute care to ‘outcomes management. ’ Med Care 1992; 30 (5 Suppl.): MS57–73Google Scholar