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The SF-36 and SGRQ: validity and first look at minimum important differences in IPF
Jeffrey J Swigris1, Kevin K Brown, Juergen Behr
1Interstitial Lung Disease Program in the Autoimmune Lung Center and Division of Psychosocial Medicine, National Jewish Health, Denver, CO, USA. swigrisj@njc.org
Respiratory Medicine
|October 10, 2009
Summary
The Short Form-36 (SF-36) and Saint George's Respiratory Questionnaire (SGRQ) are valid for tracking idiopathic pulmonary fibrosis (IPF) progression. Minimum important difference scores were established for both instruments in IPF patients.
Area of Science:
- Pulmonary Medicine
- Clinical Trials
- Health Outcomes Research
Background:
- Health-related quality of life (HRQL) is a critical endpoint in clinical trials.
- The performance of the Short Form-36 (SF-36) and Saint George's Respiratory Questionnaire (SGRQ) in idiopathic pulmonary fibrosis (IPF) requires further investigation.
Purpose of the Study:
- To assess the validity of the SF-36 and SGRQ in IPF patients.
- To establish minimum important difference (MID) scores for the SF-36 and SGRQ in IPF.
Main Methods:
- Analysis of data from a completed IPF trial including SF-36, SGRQ, and Baseline/Transition Dyspnea Index.
- Comparison of HRQL score changes based on clinical anchors (FVC, DLCO, dyspnea) over six months.
- Estimation of MID using anchor- and distribution-based methods.
Main Results:
- The SF-36 and SGRQ demonstrated validity for longitudinal studies in IPF.
- Significant differences in HRQL domain scores were observed between patients with improved and declined clinical status.
- Estimated MIDs were 2-4 points for SF-36 domains and 5-8 points for SGRQ domains.
Conclusions:
- The SF-36 and SGRQ are valid for differentiating IPF patient status changes over time.
- Further research is needed to refine MID estimates and compare these instruments with disease-specific measures.
