Creation and Validation of the European Portuguese Version of the Systemic Lupus Erythematous Quality of Life Questionnaire.

(1) Background: Patients with systemic lupus erythematous (SLE) experience profound effects on health-related quality of life (HRQoL) that cannot be explained by objective indicators of mortality and morbidity. This study aimed to adapt the SLE Quality of Life (SLEQoL) questionnaire to the European Portuguese population and to assess its reliability and validity for patients with SLE. (2) Methods: Two independent translators translated the original version of the SLEQoL questionnaire into Portuguese. A back-translated version was produced. The Portuguese version of the questionnaire was reviewed and tested for validity and reliability. Cronbach's alpha and the internal validity index were calculated to verify the internal reliability and validity of the content. Rheumatologists filled out the SLE Disease Activity Score (SLE-DAS) and Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index SLICC/ACR-DI questionnaires. (3) Results: This study involved 180 patients, of which 93.8% were females. The results indicated very high internal consistency reliability (α = 0.949), low correlations between the SLEQoL and the SLE-DAS, a correlation between all SLEQoL dimensions and all SF-36 dimensions (except for "response to treatment" and "self-image"), and good correlation scores with both the EQ-5D-5L index and VAS. (4) Conclusion: The Portuguese version of the SLEQoL questionnaire is valid and reliable for the measurement of HRQoL in SLE patients.