Abstract
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).
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Jaeschke R, Singer J, Guyatt G. Measurement of health status: ascertaining the minimal clinically important difference. Control Clin Trials 1989; 10: 407–15
Van Walraven C, Mahon JL, Moher D, et al. Surveying physicians to determine the minimal important difference: implications for sample-size calculation. J Clin Epidemiol 1999; 52: 717–23
Blackwelder WC. Similarity/equivalence trials for combination vaccines. Ann N Y Acad Sci 1995; 754: 321–8
Samsa G, Edelman D, Rothman ML, et al. Determining clinically important differences in health status measures: a general approach with illustration to the Health Utilities Index Mark II. Pharmacoeconomics 1999; 15 (2): 141–55
Ware JE, Sherbourne CD. The MOS 36-Item Short-Form Health Survey (SF-36: I. Conceptual framework and item selection. Med Care 1992; 30: 473–83
Hays RD, Hadorn D. Responsiveness to change: An aspect of validity, not a separate dimension. Qual Life Res 1992; 1: 73–5
Cohen J. A power primer. Psychol Bull 1992; 112: 155–9
Cohen J. Statistical power analysis for the behavioral sciences. 2nd ed. London: Academic Press, 1988
Wright JG, Young NL. A comparison of different indices of responsiveness. J Clin Epidemiol 1997; 50: 239–46
Barber BL, Santanello NC, Epstein RS. Impact of the global on patient perceivable change in an asthma specific QOL questionnaire. Qual Life Res 1996; 5: 117–22
Ware JE, Snow K, Kosinski M, et al. SF-36 Health Survey: manual and interpretation guide. Boston (MA): The Health Institute, 1993
Baker DW, Hays RD, Brook RH. Understanding changes in health status: is the floor phenomenon merely the last step of the staircase? Med Care 1997; 35: 1–15
Ware JE, Kosinski M, Keller SD. SF-36 physical and mental health summary scales: a user’s manual. Boston (MA): The Health Institute, 1994
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.): MS57–73
Rampal P, Martin C, Marquis P, et al. A quality of life study in five hundred and eighty-one duodenal ulcer patients: maintenance versus intermittent treatment with nizatidine. Scand J Gastroenterol 1994; 206: 44–51
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Hays, R.D., Woolley, J.M. The Concept of Clinically Meaningful Difference in Health-Related Quality-of-Life Research. Pharmacoeconomics 18, 419–423 (2000). https://doi.org/10.2165/00019053-200018050-00001
Published:
Issue Date:
DOI: https://doi.org/10.2165/00019053-200018050-00001