Three ways to quantify uncertainty in individually applied "minimally important change" values

H.C.W. de Vet, B. Terluin, D.L. Knol, LD Roorda, L.B. Mokkink, R.W.J.G. Ostelo, E.J.M. Hendriks, L.M. Bouter, C.B. Terwee

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Objective: Determining "minimally important change" (MIC) facilitates the interpretation of change scores on multi-item instruments. This article focuses on how MIC values should be interpreted when applied to individual patients.

Study Design and Setting: The MIC value of a hypothetical questionnaire "Q" was determined in a sample of 400 patients who improved and 100 patients who did not improve, using the receiver operating characteristic (ROC) method, and three methods to quantify the uncertainty.

Results: The MIC value on questionnaire Q was 10.5. Firstly, the 95% confidence interval (CI) of the MIC value (for questionnaire Q: 5.6-14.2) quantifies the uncertainty of the estimation of the MIC value. Secondly, "how sure we are that this MIC value holds for every patient" is quantified by the values for sensitivity (74%) and specificity (91%). Thirdly, the smallest detectable change (SDC) on questionnaire Q is calculated (16.0) to consider whether the MIC value (10.5) falls outside or within the measurement error.

Conclusion: For application in clinical research and practice, MIC values are always considered at the individual level, but determined in groups of patients. The interpretation comes with different forms of uncertainty. To appreciate the uncertainty, knowledge of the underlying distributions of change scores is indispensable. 

Original languageEnglish
Pages (from-to)37-45
Number of pages9
JournalJournal of Clinical Epidemiology
Volume63
Issue number1
DOIs
Publication statusPublished - 1 Jan 2010

Keywords

  • Change scores
  • Anchor-based methods
  • Minimally important change
  • ROC method
  • Outcome assessment
  • Patient-reported outcomes
  • QUALITY-OF-LIFE
  • CLINICALLY MEANINGFUL CHANGE
  • LOW-BACK-PAIN
  • HEALTH-STATUS
  • IMPORTANT DIFFERENCE
  • FUNCTIONAL STATUS
  • RESPONSIVENESS
  • QUESTIONNAIRE
  • INTENSITY
  • CONSENSUS

Cite this

de Vet, H. C. W., Terluin, B., Knol, D. L., Roorda, LD., Mokkink, L. B., Ostelo, R. W. J. G., Hendriks, E. J. M., Bouter, L. M., & Terwee, C. B. (2010). Three ways to quantify uncertainty in individually applied "minimally important change" values. Journal of Clinical Epidemiology, 63(1), 37-45. https://doi.org/10.1016/j.jclinepi.2009.03.011