Linking clinical relevance and statistical significance in evaluating intra-individual changes in health-related quality of life

Med Care. 1999 May;37(5):469-78. doi: 10.1097/00005650-199905000-00006.


Objective: To compare the standard error of measurement (SEM) with established standards for clinically relevant intra-individual change in an evaluation of health-related quality of life.

Design: Secondary analysis of data from a randomized controlled trial.

Subjects: Six hundred and five outpatients with a history of cardiac problems attending the general medicine clinics of a major academic medical center.

Measures: Baseline and follow-up interviews included a modified version of the Chronic Heart Failure Questionnaire (CHQ) and the SF-36. The SEM values corresponding to established standards for minimal clinically important differences (MCIDs) on the CHQ were determined. Individual change on the SF-36 was explored using the same SEM criterion.

Results: One-SEM changes in this population corresponded well to the patient-driven MCID standards on all CHQ dimensions (weighted kappas (0.87; P < 0.001). The distributions of outpatients who improved, remained stable, or declined (defined by the one-SEM criterion) were generally consistent between CHQ dimensions and SF-36 subscales.

Conclusions: The use of the SEM to evaluate individual patient change should be explored among other health-related quality of life instruments with established standards for clinically relevant differences. Only then can it be determined whether the one-SEM criterion can be consistently applied as a proxy for clinically meaningful change.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Analysis of Variance
  • Bias
  • Chronic Disease
  • Coronary Disease / epidemiology
  • Female
  • Health Status Indicators*
  • Heart Failure / epidemiology
  • Humans
  • Interviews as Topic / methods
  • Lung Diseases, Obstructive / epidemiology
  • Male
  • Middle Aged
  • Quality of Life*
  • Surveys and Questionnaires