Validation and cross-cultural adaptation of the Thai version of the Systemic Sclerosis Health Assessment Questionnaire.

BACKGROUND

The Scleroderma Health Assessment Questionnaire (S-HAQ), including the Disability Index (HAQ-DI) and six-symptom visual analog scales (VAS), assesses functional ability in systemic sclerosis (SSc). The Thai HAQ-DI has been validated, but not the S-HAQ VAS.

OBJECTIVE

We aim to translate and culturally adapt the VAS for symptoms in S-HAQ and assess its validity and reliability.

METHOD

The six VAS items, which assess pain, gastrointestinal symptoms, respiratory symptoms, Raynaud's phenomenon (RP), digital ulcers (DU), and overall disease activity interfering with daily activities, were translated into Thai and validated. Thirty SSc patients completed the translated questionnaire twice, with a one-week interval. Intraclass correlation (ICC) was used for test-retest reliability, and Spearman correlation was used to test the reliability of the associated clinical parameters and the S-HAQ VAS.

RESULT

For the validity testing, the VAS for pain, respiratory symptoms, RP, DU, and overall disease activity showed significant correlations with the modified Rodnan skin score (mRSS) (Rho = 0.508, 0.550, 0.474, 0.492, and 0.557, respectively) and with the EuroQol visual analog scale (EQ VAS) (Rho =  - 0.652, - 0.697, - 0.568, - 0.581, and - 0.668, respectively). Additionally, the World Health Organization functional class demonstrated significant correlations with both the VAS overall disease activity and the HAQ-DI (Rho = 0.473 and 0.460, respectively). The HAQ-DI showed significant correlations with all the S-HAQ VAS questions. The reliability testing indicated a strong ICC between two testing sessions for each VAS item in the S-HAQ, with coefficient values ranging from 0.777 to 0.940.

CONCLUSION

This study substantiates the utility of the Thai S-HAQ VAS as a valid measure for assessing function and disability in patients with SSc. The translated Thai version of the S-HAQ VAS exhibits high reliability, demonstrated by strong ICC between two testing sessions. Key Points • The Thai version of the Scleroderma Health Assessment Questionnaire (S-HAQ) visual analog scale (VAS) was successfully translated and culturally adapted. It provides a reliable and valid tool for assessing systemic sclerosis (SSc) symptoms and disability in native Thai patients. • Strong test-retest reliability was demonstrated for all six VAS items, with intraclass correlation (ICC) values ranging from 0.777 to 0.940 and the validity testing showed significant correlations between S-HAQ VAS scores and clinical parameters, including mRSS, EQ-VAS, and WHO functional class. • The availability of this validated tool enables Thai researchers to participate in international SSc clinical trials and comparative studies using standardized outcome measures, enhancing global research collaboration.