Background SLE complexity and unpredictability challenge assessment of disease activity. Current scoring instruments are limited in ability to detect changes in activity over time and too cumbersome for daily practice. We constructed a new disease activity score, including physician and patient assessment, aiming to simplify and improve assessment in daily practice, and possibly serve as a tool for clinical studies.

Methods The new instrument is comprised of 6 visual analogue scales, separately addressing the physician’s global assessment and 5 organ systems: mucocutaneous, musculoskeletal, cardiorespiratory, renal and neuropsychiatric systems, and 5 visual analogue scales addressing patients’ assessment of disease activity and adherence to therapy. Laboratory values and medications are recorded. Aiming to assess the reliability and validity of the new score, as well as it’s sensitivity to changes in disease activity, 4 paper cases, including 2 visits per case, were constructed. Each visit was scored by 5 experienced rheumatologists, using BILAG, SLEDAI, LFA-REAL and our proposed score.

Results The inter-rater reliability of the new score was good for all systems, both for single visit scores and for change in disease activity between 2 consecutive visits (ICC [2,1] range 0.75–0.95), except for changes in activity in the renal system (0.59). The inter-rater reliability values of the new score were comparable with those of the BILAG and the LFA-REAL instruments. The construct validity of the new score was good for single visit scores (Spearman correlation coefficients range 0.48–0.94). Correlation of our proposed score with the BILAG, was good when scoring the mucocutaneous, musculoskeletal and cardiorespiratory systems (0.66, 0.75, 0.83, respectively) but poor when scoring the renal system (0.11).

Conclusions This paper case evaluation of the new disease activity score suggests a promising and simple tool, with overall good reliability and construct validity.