Translation and validation of non-English versions of the Ankylosing Spondylitis Quality of Life (ASQOL) questionnaire.
BACKGROUND
The Ankylosing Spondylitis Quality of Life (ASQOL) questionnaire is a unidimensional, disease-specific measure developed in the UK and the Netherlands. This study describes its adaptation into other languages.


METHODS
The UK English ASQOL was translated into US English; Canadian French and English; French; German; Italian; Spanish; and Swedish (dual-panel methods). Cognitive debriefing interviews were conducted with AS patients. Psychometric/scaling properties were assessed using data from two Phase III studies of adalimumab. Baseline and Week-2 data were used to assess test-retest reliability. Validity was determined by correlation of ASQOL with SF-36 and BASFI and by discriminative ability of ASQOL based on disease severity. Item response theory (Rasch model) was used to test ASQOL's scaling properties.


RESULTS
Cognitive debriefing showed the new ASQOL versions to be clear, relevant and comprehensive. Sample sizes varied, but were sufficient for: psychometric/scaling assessment for US English and Canadian English; psychometric but not scaling analyses for German; and preliminary evidence of these properties for the remaining languages. Test-retest reliability and Cronbach's alpha coefficients were high: US English (0.85, 0.85), Canadian English (0.87, 0.86), and German (0.77, 0.79). Correlations of ASQOL with SF-36 and BASFI for US English, Canadian English, and German measures were moderate, but ASQOL discriminated between patients based on perceived disease severities (p < 0.01). Results were comparable for the other languages. US English and Canadian English exhibited fit to the Rasch model (non-significant p-values: 0.54, 0.68), confirming unidimensionality.


CONCLUSIONS
The ASQOL was successfully translated into all eight languages. Psychometric properties were excellent for US English, Canadian English, and German, and extremely promising for the other languages.
Doward
Lynda C
LC
Galen Research, Manchester, UK. ldoward@galen-research.com
McKenna
Stephen P
SP
Meads
David M
DM
Twiss
James
J
Revicki
Dennis
D
Wong
Robert L
RL
Luo
Michelle P
MP
D000293:Adolescent; D000328:Adult; D000368:Aged; D005060:Europe; D005260:Female; D006801:Humans; D007802:Language; D008297:Male; D008875:Middle Aged; D011594:Psychometrics / Q000379:methods*; D011788:Quality of Life; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D013167:Spondylitis, Ankylosing / Q000145:classification / Q000523:psychology*; D011795:Surveys and Questionnaires; D014481:United States