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Linking measurement error to minimal important change of patient-reported outcomes

Caroline B Terwee1, Leo D Roorda, Dirk L Knol

  • 1Department of Epidemiology and Biostatistics, EMGO Institute, VU University Medical Center, Amsterdam, The Netherlands. cb.terwee@vumc.nl

Journal of Clinical Epidemiology
|February 24, 2009
PubMed
Abstract

Insights

Researchers should report the standard error of measurement (SEM) and minimal important change (MIC) for patient-reported outcomes (PROs). This helps estimate sample sizes for studies and assess PROs

Area of Science:

  • Health Outcomes Research
  • Clinical Measurement
  • Patient-Reported Outcomes (PROs)

Background:

  • Measurement error is a critical factor in assessing the reliability of patient-reported outcomes (PROs).
  • Understanding the minimal important change (MIC) is essential for interpreting the clinical significance of PRO data.
  • Estimating appropriate sample sizes is crucial for the validity of research findings.

Purpose of the Study:

  • To demonstrate how to link measurement error (SEM) with minimal important change (MIC) for sample size estimation in research.
  • To evaluate the utility of PROs in routine clinical practice for monitoring patient progress.

Main Methods:

  • Calculated the standard error of measurement (SEM) as a measure of error.
  • Determined MIC by comparing mean score changes in patients reporting improvement versus no change on a global rating scale.
  • Developed formulas for sample size estimation and assessing clinical utility based on SEM and MIC.

Main Results:

  • A practical example is provided using the Western Ontario and McMaster University Osteoarthritis Index (WOMI) data.
  • Demonstrated the application of SEM and MIC for sample size calculations in a real-world clinical scenario.

Conclusions:

  • Investigators are urged to report SEM and MIC for their PROs.
  • Utilizing SEM and MIC is recommended for accurate sample size determination in research.
  • SEM and MIC are valuable for assessing the clinical usefulness of PROs in daily practice.

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