Background/Purpose: Traditional assessments of systemic lupus erythematosus (SLE) disease activity, such as the SLE Disease Activity Index 2000 (SLEDAI-2K) and the Systemic Lupus Activity Measure (SLAM), rely on a physician-obtained history, physical examination, and laboratory evaluation and thus may prove impractical and costly especially for large epidemiologic studies. The Systemic Lupus Activity Questionnaire (SLAQ) was developed based on the SLAM as a more economical way of following and tracking large groups of SLE patients who may be at a distance from a center in epidemiologic studies. The purpose of the present study was to translate and adapt the SLAQ to Japanese and further investigate its validity and reliability using a prospective observational cohort of SLE patients followed at a single university clinic while their physicians score the SLEDAI-2K.

Methods: The English version of the SLAQ was translated, back-translated and culturally adapted to Japanese using standard methodology. Japanese SLE patients who had 4 or more revised American College of Rheumatology (ACR) criteria for SLE were approached during their outpatient attendance in our university clinic. Some of the hospitalized patients during the study period were also eligible to the study. Patients were asked to complete the SLAQ and other related demographic questionnaires such as Medical Outcomes Study Short Form-36 (SF-36) and physicians were asked to complete the SLEDAI-2K and the Systemic Lupus International Collaborating Clinics (SLICC)/ACR Damage Index (SDI). Laboratory items were omitted from SLEDAI-2K scores in this study and the instrument will be called SLEDAI-2K-nolab. Patients were prospectively followed for repeat assessment next year.

Results: A total of 246 patients and 30 physicians (all rheumatologists) participated. The acceptability of the SLAQ was high, with most of items having 100% response rate. The distribution of the SLAQ, the SLEDAI-2K, and the SLEDAI-2K-nolab all skewed to the right. The median SLAQ score was 5 (range 0–32) and the median SLEDAI-2K score was 2 (range 0–18). The SLAQ had a weak correlation with the SLEDAI-2K-nolab (Spearman’s ρ = 0.18, p = 0.005) but not with SLEDAI-2K (p = 0.71). The SLAQ demonstrated acceptable internal consistency, with a Cronbach’s alpha of 0.78. The SLAQ showed weak correlation with the SDI, and moderate correlation with physical and mental component summary scores of the SF-36 (Spearman’s ρ = 0.17, -0.53, and -0.54, respectively). Twenty-five patients with stable disease were asked to repeat the SLAQ after 2 weeks and the intraclass correlation coefficient was 0.85, which means good test–retest reliability. These figures come from the first year research and the second year gave similar results. The SLAQ did not demonstrate a good responsiveness by the longitudinal analyses.

Conclusion: We have successfully translated, adapted and validated the Japanese version of the SLAQ. There is evidence of acceptable reliability and validity of the Japanese version of the SLAQ among Japanese patients with SLE. Our study provides evidence of the cross-cultural validity of this tool and can be used to assess disease activities among Japanese patients with SLE.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/validity-and-reliability-of-the-systemic-lupus-activity-questionnaire-slaq-a-prospective-study/