Translation, Cultural Adaptation and Validation of Health-Related Quality of Life Assessment Tools: A Brazilian Perspective on Patients with Systemic Lupus Erythematosus

Abstract:

There has been increasing interest and investigation into the quality of life parameter in the assessment of chronic disease. There are no quality of life assessment instruments specific to Systemic Lupus Erythematosus in the Portuguese language.

Therefore, we translated into Portuguese, culturally adapted and assessed the reliability and validity of the Systemic Lupus Erythematosus Quality of Life (SLEQOL) and Systemic Lupus Erythematosus Symptom Checklist (SSC) questionnaires.

We studied 107 patients with lupus (according to ACR criteria) over 16 years of age who responded to the SLEQOL, SSC and SF-36 during four visits over the course of 1 year with the aim of translating the instruments and determining their psychometric properties. Following the authorization from the respective authors, translation and cultural adaptation of the questionnaires into the Portuguese language was performed in accordance with studies on questionnaire translation methodology. Reliability was analyzed through three interviews with different interviewers: two on the same day (inter-observer) and a third interview conducted by one of the interviewers within 14 days of the first evaluation (intra-observer). Validity was assessed through correlations between clinical and quality of life parameters as assessed by the SLEQOL and SSC. Descriptive analysis was performed for the characterization of the sample. The intraclass correlation coefficient was used to assess intra-observer and inter-observer reproducibility. Internal consistency of the items was assessed using Cronbach’s alpha coefficient. Pearson’s correlation coefficient was used to study validity. The level of significance for all statistical tests was set at 5%.

The main results obtained for the SLEQOL were a 0.807 correlation coefficient for internal consistency for all questions and domains as well as a 0.990 inter-observer and 0.969 intra-observer correlation coefficient. The correlation coefficients for internal consistency, intra-observer reliability and inter-observer reliability for the SSC were 0.874, 0.925 and 0.917, respectively. In the validation, both the SLEQOL and the SSC demonstrated a moderate correlation with the SF-36, but a low correlation with disease activity and damage.

The SLEQOL and SSC are broad-based, easily administered questionnaires. The SLEQOL performs well in assessing physical symptoms and the mental status and wellbeing of patients. Both instruments are robust, exhibiting reliability and validity.