Brazilian version of the “Primary Sjögren’s Syndrome - Quality of Life questionnaire (PSS-QoL)”: translation, cross-cultural adaptation and validation

Abstract

Abstract Background The Primary Sjögren’s Syndrome Quality of Life questionnaire (PSS-QoL) is the first specific instrument to assess health-related quality of life (HRQoL) in Sjögren’s disease (SjD). The aim is to translate and cross-culturally adapt the PSS-QoL into Brazilian Portuguese and to evaluate its psychometric properties. Methods The original English version was translated into Brazilian Portuguese by two native Brazilians who were proficient in the English language. The retranslation was conducted by two native Americans proficient in Brazilian Portuguese. A committee undertook an analysis of the translated and retranslated versions, resulting in the generation of the first Brazilian version, which was submitted to the cross-cultural adaptation phase. In this phase, 50 participants with SjD responded to the instrument in Stages I and II, resulting in the generation of the second and final Brazilian version. To assess the psychometric properties, demographic and clinical data were collected from 75 patients. The HRQoL questionnaires (final Brazilian version of the PSS-QoL, Short Form-36 Health Survey (SF-36) and EuroQoL-5 dimension (EQ-5D)) were completed. Construct validity was analyzed using the Pearson or Spearman correlation coefficient. Reliability was analyzed using Cronbach’s alpha and the intraclass correlation coefficient (ICC). Results Eight questions and one response item were revised due to an incomprehension rate of greater than 15% among the participants in the cross-cultural adaptation phase. The final Brazilian version of the PSS-QoL was validated, revealing a high correlation between the total score and functional capacity (r= −0.713, p < 0.001), and vitality (r= −0.770, p < 0. 001) and mental health (r= −0.742, p < 0.001) domains of the SF-36 and a moderate correlation with the other domains of the SF-36 and a moderate correlation with the EQ-5D-tto (r= −0.573, p < 0.001), and EQ-5D-VAS (r= −0.559, p < 0.001). The intraobserver (ICC = 0.939; Cronbach’s alpha = 0.964) and interobserver (ICC = 0.965; Cronbach’s alpha = 0.964) reliability of the total score showed very high consistency. Conclusion The Brazilian version of the PSS-QoL has been demonstrated to be a valid and reproducible instrument for the assessment of HRQoL in patients with SjD.