Further Evidence Supporting an SEM-Based Criterion for Identifying Meaningful Intra-Individual Changes in Health-Related Quality of Life

• Published in: Journal of clinical epidemiology 1999-09, Vol.52 (9), p.861-873
• Main Authors: Wyrwich, Kathleen W., Tierney, William M., Wolinsky, Fredric D.
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aged, 80 and over; Biological and medical sciences; chronic obstructive pulmonary disease; Chronic obstructive pulmonary disease, asthma; clinical change; Data Interpretation, Statistical; Disease Progression; Epidemiology; Female; Follow-Up Studies; General aspects; Health Status Indicators; Humans; Lung Diseases, Obstructive - diagnosis; Lung Diseases, Obstructive - psychology; Male; measurement; Medical sciences; Methodology; Middle Aged; Outpatients; Pneumology; Public health. Hygiene; Public health. Hygiene-occupational medicine; Quality of Life; Reproducibility of Results; responsiveness; Retrospective Studies; sensitivity; Severity of Illness Index; Surveys and Questionnaires
• ISSN: 0895-4356; 1878-5921
• DOI: 10.1016/S0895-4356(99)00071-2

This study used the standard error of measurement (SEM) to evaluate intra-individual change on both the Chronic Respiratory Disease Questionnaire (CRQ) and the SF-36. After analyzing the reliability and validity of both instruments at baseline among 471 COPD outpatients, the SEM was compared to established minimal clinically important difference (MCID) standards for three CRQ dimensions. A value of one SEM closely approximated the MCID standards for all CRQ dimensions. This SEM-based criterion was then validated by cross-classifying the change status (improved, stable, or declined) of 393 follow-up outpatients using the one-SEM criterion and the MCID standard. Excellent agreement was achieved for all three CRQ dimensions. Although MCID standards have not been established for the SF-36, the one-SEM criterion was explored in these change scores. Among SF-36 scales demonstrating acceptable reliability and reasonable variance, the percent of individuals within each change category was consistent with those seen in the CRQ dimensions. These results replicate previous findings where a value of one SEM also closely approximated MCIDs for all dimensions of the Chronic Heart Disease Questionnaire among cardiovascular outpatients. The one-SEM criterion should be explored in other health-related quality of life instruments with established MCIDs.