Because Drs. Yelin and Katz are Editors of Arthritis Care & Research, review of this article was handled by the Editor of Arthritis & Rheumatism.
Systemic Lupus Erythematosus
Validation of the systemic lupus erythematosus activity questionnaire in a large observational cohort
Article first published online: 28 DEC 2007
Copyright © 2008 by the American College of Rheumatology
Arthritis Care & Research
Volume 59, Issue 1, pages 136–143, January 2008
How to Cite
Yazdany, J., Yelin, E. H., Panopalis, P., Trupin, L., Julian, L. and Katz, P. P. (2008), Validation of the systemic lupus erythematosus activity questionnaire in a large observational cohort. Arthritis & Rheumatism, 59: 136–143. doi: 10.1002/art.23238
- Issue published online: 28 DEC 2007
- Article first published online: 28 DEC 2007
- Manuscript Accepted: 4 JUN 2007
- Manuscript Received: 1 MAR 2007
- General Clinical Research Center, Moffit Hospital, University of California, San Francisco, United States Public Health Service
- Rosalind Russell Medical Research Center for Arthritis
- National Center for Research Resources. Grant Number: 5-M01-RR-00079
- American College of Rheumatology/Research and Education Foundation Physician Scientist Development Award
- State of California Lupus Fund
- Arthritis Foundation
- Agency for Healthcare Research and Quality/National Institute of Arthritis and Musculoskeletal and Skin Diseases. Grant Number: 1-R01-HS013893
To examine the reliability, construct validity, and responsiveness of the Systemic Lupus Erythematosus Activity Questionnaire (SLAQ) in a large observational cohort of persons with systemic lupus erythematosus (SLE).
We evaluated the reliability of the SLAQ using Cronbach's alpha and principal factor analysis and ascertained construct validity by studying the association of the SLAQ with other clinically relevant, validated patient assessments of health. We estimated responsiveness by calculating standardized response means and analyzing the association of changes in SLAQ scores with changes in other patient assessments of health.
The SLAQ had excellent reliability, as reflected by Cronbach's alpha (0.87) and principal factor analysis (one factor accounted for 92% of the variance). SLAQ scores were strongly correlated with other health indices, including the Short Form 12 Physical Component Summary and the Short Form 36 Physical Functioning subscale. Scores were significantly higher for respondents reporting a flare, more disease activity, hospitalization in the last year, concurrent use of immunosuppressive medication, and work disability. The SLAQ demonstrated a small to moderate degree of responsiveness; standardized response means were 0.66 and −0.37 for those reporting clinical worsening and improvement, respectively. Across a range of other patient assessments of disease status, the SLAQ had a response in the direction predicted by these other measures.
The SLAQ demonstrates adequate reliability, construct validity, and responsiveness in our large, community-based cohort and appears to represent a promising tool for studies of SLE outside the clinical setting.