The Health Assessment Questionnaire Disability Index (HAQ-DI) was completed with five visual analog scales to assess systemic sclerosis (SSc) called Scleroderma HAQ (SHAQ). We performed a validation of the European Portuguese version of SHAQ for patients with SSc. Patients with different forms of SSc from five Hospital Centers were invited. The reliability of the Portuguese SHAQ was evaluated by internal consistency and by test-retest reliability. Content validity was checked by two rheumatologists and by a panel of patients. Construct validity was assessed by structural validity and by known-groups hypothesis tests. Criterion validity was addressed with selected dimensions from the UCLA GIT 2.0, the SF-36v2, and the EuroQoL EQ-5D-5L. A total of 102 SSc patients agreed to participate, 31 of which answered to the retest. HAQ-DI demonstrated high internal consistency reliability (α = 0.866) and SHAQ also showed high test-retest reliability (ICC 0.61-0.95). We evidenced the unidimensionality of all VASs. HAQ-DI scores were 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 the HAQ-DI and SF-36v2 physical summary measure (r = -0.688) and EQ-5D-5L index score (r = -0.723). Likewise, the SHAQ overall disease severity VAS was also correlated with SF-36v2 physical summary measure (r = -0.628). Mental score correlations were smaller. With the exception of the Raynaud's VAS, all the other VASs correlated well with similar clinical variables. 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.
Keywords: SHAQ; outcome assessment; quality of life; systemic sclerosis.