Background The English version of the Systemic Lupus Erythematosus Quality of Life Questionnaire (SLEQOL) is a validated disease-specific quality of life instrument. According to the domains of health related quality of life (HRQoL) affected by systemic lupus erythematosus (SLE) that may vary in a different socio-cultural context, we therefore selected to translate the SLEQOL into a Thai version.
Objectives to determine the validity of the SLEQOL-TH in assessing the HRQoL of Thai patients with SLE.
Methods Two independent translators translated the SLEQOL into Thai. The back translation of this version was performed by another two independent translators. The final version, SLEQOL-TH, was completed after resolving the discrepancies revealed by the back translation. One hundred and nine patients with SLE were enrolled to test the reliability, construct validity, floor and ceiling effects, and sensitivity to the changes of the SLEQOL-TH at six months. The differential item functioning (DIF) between the Thai and English versions was analyzed using the partial gamma.
Results The internal consistency of the SLEQOL-TH was satisfactory with the overall Cronbach alpha of 0.86. The test-retest reliability of the SLEQOL-TH was acceptable with the intra-class correlation coefficient of 0.86. Low correlations between the SLEQOL-TH and SLEDAI were observed. The total score of the SLEQOL-TH was moderately responsive to the changes, with a standardized response mean of 0.50. Comparing the SLEQOL-TH from Thai SLE patients with the original SLEQOL version obtained from Singapore SLE patients, 11 out of 40 items showed a moderate to large DIF.
Conclusions The SLEQOL-TH is psychometrically sound and shows construct validity. In comparison with the English version of SLEQOL, there are some items which showed DIF. The applicability of the SLEQOL-TH in real life clinical practice and clinical trials needs to be determined.
Disclosure of Interest None Declared