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Quality of Life Research

, Volume 23, Issue 1, pp 1–4 | Cite as

Don’t middle your MIDs: regression to the mean shrinks estimates of minimally important differences

  • Peter M. Fayers
  • Ron D. Hays
Article

Abstract

Minimal important differences (MIDs) for patient-reported outcomes (PROs) are often estimated by selecting a clinical variable to serve as an anchor. Then, differences in the clinical anchor regarded as clinically meaningful or important can be used to estimate the corresponding value of the PRO. Although these MID values are sometimes estimated by regression techniques, we show that this is a biased procedure and should not be used; alternative methods are proposed.

Keywords

Minimally important difference Clinical significance Quality of life Patient-reported outcomes Regression to the mean 

Abbreviations

MCID

Minimal clinically important difference

MID

Minimal important difference

r

Correlation coefficient

NEI VFQ-25

Eye Institute Visual Function Questionnaire-25

PRO

Patient-reported outcome

SD

Standard deviation

Notes

Acknowledgments

Ron D. Hays was supported in part by grants from the NIA (P30-AG021684) and the NIMHD (P20MD000182).

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Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  1. 1.Institute of Applied Health SciencesUniversity of AberdeenAberdeenUK
  2. 2.Department of Cancer Research and Molecular MedicineNorwegian University of Science and Technology (NTNU)TrondheimNorway
  3. 3.Department of MedicineUCLALos AngelesUSA

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