Development of the ASQoL: a quality of life instrument specific to ankylosing spondylitis

L C Doward, A Spoorenberg, S A Cook, D Whalley, P S Helliwell, L J Kay, S P McKenna, A Tennant, D van der Heijde, M A Chamberlain, L C Doward, A Spoorenberg, S A Cook, D Whalley, P S Helliwell, L J Kay, S P McKenna, A Tennant, D van der Heijde, M A Chamberlain

Abstract

Background: Although disease-specific health status measures are available for ankylosing spondylitis (AS), no instrument exists for assessing quality of life (QoL) in the condition.

Objective: To produce an AS-specific QoL measure that would be relevant and acceptable to respondents, valid, and reliable.

Methods: The ASQoL employs the needs-based model of QoL and was developed in parallel in the UK and the Netherlands (NL). Content was derived from interviews with patients in each country. Face and content validity were assessed through patient field test interviews (UK and NL). A postal survey in the UK produced a more efficient version of the ASQoL, which was tested for scaling properties, reliability, internal consistency, and validity in a further postal survey in each country.

Results: A 41 item questionnaire was derived from interview transcripts. Field testing interviews confirmed acceptability. Rasch analysis of data from the first survey (n=121) produced a 26 item questionnaire. Rasch analysis of data from the second survey (UK: n=164; NL: n=154) showed some item misfit, but showed that items formed a hierarchical order and were stable over time. Problematic items were removed giving an 18 item scale. Both language versions had excellent internal consistency (alpha=0.89-0.91), test-retest reliability (r(s)=0.92 UK and r(s)=0.91 NL), and validity.

Conclusions: The ASQoL provides a valuable tool for assessing the impact of interventions for AS and for evaluating models of service delivery. It is well accepted by patients, taking about four minutes to complete, and has excellent scaling and psychometric properties.

Figures

Figure 1
Figure 1
Stages in production of the ASQoL

References

    1. J Rheumatol. 1990 Jul;17(7):946-50
    1. Health Policy. 1992 Oct;22(3):307-19
    1. Health Policy. 1992 Oct;22(3):321-30
    1. Br J Rheumatol. 1994 Sep;33(9):842-6
    1. Br J Rheumatol. 1994 Nov;33(11):1060-6
    1. J Rheumatol. 1994 Dec;21(12):2281-5
    1. Qual Life Res. 1996 Aug;5(4):443-9
    1. Br J Rheumatol. 1997 Aug;36(8):878-83
    1. Br J Rheumatol. 1997 Aug;36(8):884-8
    1. Qual Life Res. 1998 Feb;7(2):143-53
    1. J Outcome Meas. 1998;2(1):66-78
    1. Qual Life Res. 1999 Jun;8(4):373-83
    1. Int Rehabil Med. 1983;5(3):149-53
    1. Soc Sci Med A. 1981 May;15(3 Pt 1):221-9
    1. Arthritis Care Res. 1999 Jun;12(3):157-62
    1. Arthritis Rheum. 1984 Apr;27(4):361-8
    1. J Rheumatol. 1988 Feb;15(2):302-7

Source: PubMed

スポンサーと協力者

医学的状態

薬物療法

3
購読する