Validation of the Portuguese version of the Scleroderma Health Assessment Questionnaire

Abstract Background The Health Assessment Questionnaire Disability Index (HAQ-DI) was completed with five visual analogue scales (VAS) to assess systemic sclerosis (SSc). These VAS address overall disease severity, Raynaud’s phenomenon, digital tip ulcers, gastrointestinal and lung symptoms. The new functional measurement instrument is called Scleroderma HAQ (SHAQ). It aims to perform a validation of the European Portuguese version of SHAQ for patients with SSc. Methods Patients with different forms of SSc from five Hospital Centres’ Rheumatology Departments were invited. The reliability of the Portuguese SHAQ was evaluated by internal consistency, using the Cronbach’s α, and by test-retest reliability, using the intraclass correlation coefficient (ICC). Construct validity was assessed by structural validity using factor analysis, and by known-groups hypotheses tests. Criterion validity was addressed by Pearson’s correlation with selected dimensions from the University of California Los Angeles Scleroderma Clinical Trial Consortium Gastrointestinal Tract Instrument (UCLA GIT 2.0), the Short Form Health Survey (SF-36v2), and the EuroQoL EQ-5D-5L. Results One hundred and two SSc patients agreed to participate, 31 of which answered to the retest. HAQ-DI demonstrated high internal consistency reliability (α=0.866) and the same measure and all five VAS also showed high test-retest reliability (ICC 0.61–0.95). In what concerns construct validity, we evidenced the unidimensionality of all VAS. HAQ-DI evidenced to be worse in males, patients older than 65 years and individuals with a diffuse form of SSc. Criterion validity was mainly evidenced through the correlation between HAQ-DI and SF-36v2 physical summary measure (r=-0.688) and EQ-5D-5L index score (r=-0.723). Likewise, SHAQ overall disease severity VAS was also correlated with SF-36v2 physical summary measure (r=-0.628). Because SHAQ is a functional disability measure, mental scores correlations were smaller. With the exception of Raynaud’s VAS, all the other VAS correlated well with similar clinical variables. Conclusion This paper provides evidence to demonstrate how reliable and valid the European Portuguese version of SHAQ is, to be used in SSc patients to assess the clinical severity under the perspective of patients.