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Development and validity testing of an IPF-specific version of the St George's Respiratory Questionnaire

Yorke, J, Jones, PW and Swigris, JJ 2010, 'Development and validity testing of an IPF-specific version of the St George's Respiratory Questionnaire' , Thorax, 65 (10) , pp. 921-926.

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    Abstract

    Rationale The St George's Respiratory Questionnaire (SGRQ) is often applied to assess health-related quality of life in patients with idiopathic pulmonary fibrosis (IPF). Some SGRQ items will inevitably have weaker measurement properties than others when applied to this population. This study was conducted to develop an IPF-specific version of the SGRQ. Methods Data from a recently completed trial that enrolled subjects with IPF (n=158) who completed the SGRQ and other measures were analysed at baseline and 6 months. There were four phases to the study: (1) removing items with missing responses and using Rasch analysis on retained items to identify fit and refine item response categories; (2) development of a new scoring scheme; (3) testing agreement between original and revised versions and testing construct validity of the revised SGRQ; and (4) rewording to finalise the IPF-specific version (SGRQ-I). Results Items were removed due to missing responses (6 items) and misfit to the Rasch model (10 items); 34 items from the original 50 were retained. For certain items, disordered response thresholds were identified and corrected by collapsing response categories. A scoring algorithm was developed to place SGRQ-I scores on a scale with SGRQ scores. For any given outcome measure (eg, forced vital capacity (% predicted) and lung carbon monoxide transfer factor (% predicted), 6-min walk distance and patient-reported questionnaires), Pearson correlations were similar between pairs that included original SGRQ scores and corresponding pairs that included SGRQ-I scores. Internal reliability (Cronbach α) for each SGRQ-I component was comparable to the original SGRQ (Symptoms 0.62; Activities 0.80; Impacts 0.85). Conclusions The SGRQ-I contains items from the original SGRQ that are the most reliable for measuring health-related quality of life in patients with IPF.

    Item Type: Article
    Themes: Subjects / Themes > R Medicine > R Medicine (General)
    Health and Wellbeing
    Schools: Colleges and Schools > College of Health & Social Care > School of Nursing, Midwifery, Social Work & Social Sciences > Centre for Nursing, Midwifery & Social Work Research
    Colleges and Schools > College of Health & Social Care
    Colleges and Schools > College of Health & Social Care > School of Nursing, Midwifery, Social Work & Social Sciences
    Journal or Publication Title: Thorax
    Publisher: BMJ Publishing Group
    Refereed: Yes
    ISSN: 0040-6376
    Depositing User: Users 29196 not found.
    Date Deposited: 24 Jan 2011 15:13
    Last Modified: 20 Aug 2013 17:46
    URI: http://usir.salford.ac.uk/id/eprint/12817

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