Translation, cultural adaptation and validation of the Systemic Lupus Erythematosus Activity Questionnaire (SLAQ) in a cohort of Italian systemic lupus erythematosus patients

Introduction The Systemic Lupus Erythematosus Activity Questionnaire (SLAQ) is a patient-reported instrument for the assessment of disease activity in systemic lupus erythematosus (SLE). The aims of the present study are translation, cultural adaptation and validation of an Italian version: the SLAQit. Methods The process of translation and cultural adaptation followed published guidelines. SLAQit was pretested in a group of 35 SLE patients to evaluate acceptability, comprehension and feasibility. Internal consistency, test–retest validity and external validity were tested on consecutive SLE patients attending the clinic. Results In total, 135 SLE patients were enrolled in this study. The pilot test provided a 99.9% response rate and demonstrated feasibility and comprehensibility of the questionnaire. A good internal consistency was found among the three components of the score (SLAQ score, numerical rating scale (NRS), patient global assessment question (PGA); α = 0.79). SLAQit showed very high reliability (test–retest α > 0.8). NRS and PGA showed a strong positive correlation with both Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) ( p = 0.002 and p < 0.001, respectively) and European Consensus Lupus Measurement (ECLAM) scores ( p = 0.01 and p < 0.001, respectively), while the SLAQ score did not. A significant agreement was observed between the physician's intention to treat and both the NRS and PGA scores, while no significant association was reported with the SLAQ score. Conclusions SLAQit was demonstrated to be a reliable and valid instrument for self-assessment of disease activity in SLE patients.