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Ann Rheum Dis 2009;68:196-200 doi:10.1136/ard.2007.086009
  • Clinical and epidemiological research

The development of the L-QoL: a quality-of-life instrument specific to systemic lupus erythematosus

  1. L C Doward1,
  2. S P McKenna1,2,
  3. D Whalley3,
  4. A Tennant4,
  5. B Griffiths5,
  6. P Emery4,
  7. D J Veale6
  1. 1
    Galen Research, Manchester Science Park, Manchester, UK
  2. 2
    School of Psychology, University of Central Lancashire, Preston, UK
  3. 3
    NPCRDC, The University of Manchester, Manchester, UK
  4. 4
    Academic Unit of Musculoskeletal and Rehabilitation Medicine, University of Leeds, Leeds, UK
  5. 5
    Department of Rheumatology, The Freeman Hospital, High Heaton, Newcastle Upon Tyne, UK
  6. 6
    St Vincent’s University Hospital, Dublin, Ireland
  1. Lynda C Doward, Director & Principal Researcher, Galen Research, Enterprise House, Manchester Science Park, Lloyd Street North, Manchester M15 6SE, UK; ldoward{at}galen-research.com
  • Accepted 16 March 2008
  • Published Online First 2 April 2008

Abstract

Objectives: Complex diseases, such as systemic lupus erythematosus (SLE), present dilemmas over choice of outcome measures. Using a battery of instruments to capture the impact of different impairments or activity limitations experienced does not provide assessment of the wider impact on quality of life (QoL). This paper describes the development and testing of a new instrument to measure QoL in systemic lupus erythematosus (L-QoL).

Methods: The development combines theoretical strengths of the needs-based QoL model with statistical and diagnostic powers of the Rasch model. Content was derived from in-depth interviews with relevant patients. Cognitive debriefing interviews assessed face and content validity. Rasch analysis was applied to data from an initial postal survey to remove misfitting items. A second postal survey assessed scaling properties, reliability, internal consistency and validity.

Results: A 55-item questionnaire was derived from interview transcripts. Cognitive debriefing confirmed acceptability. Rasch analysis of postal survey data (n = 95) removed misfitting items. A second postal survey (n = 93), produced a 25-item version with good item fit and stability, excellent test–retest reliability (0.92), internal consistency (0.92) and strict unidimensionality.

Conclusions: It is concluded that the L-QoL should prove a valuable instrument for assessing patient-based outcome in clinical trials and practice.

Footnotes

  • Competing interests: None.

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