LAMDA as an SLE-related arthritis disease measure

Results from a study to derive and validate the Lupus Arthritis and Musculoskeletal Disease Activity (LAMDA) instrument to measure objective inflammation and patient-reported symptoms in patients with systemic lupus erythematosus (SLE)-related arthritis were published in The Lancet Rheumatology by Wood et al. Data were derived from the prospective, multicenter USEFUL study, which assessed the ability of ultrasound status at baseline to predict treatment responses. 

Key data: LAMDA was derived from 133 patients using penalized regression against bilateral hand and wrist ultrasound synovitis scores, retaining four components: swollen joint count in 66 joints (SJC66), erythrocyte sedimentation rate (ESR), physician musculoskeletal disease activity visual analog scale (VAS), and participant musculoskeletal pain VAS. Due to high intraclass correlation (intraclass correlation coefficient [ICC], 0.99), SJC66 was replaced with SJC28 (LAMDA28) to improve feasibility. LAMDA28 demonstrated good convergent validity, correlating with number of ultrasound-active joints (p < 0.0001), Outcome Measures in Rheumatology (OMERACT) Global OMERACT and European Alliance of Associations for Rheumatology Ultrasound Synovitis Score (GLOESS) joint score (p < 0.0001), lupus quality of life (QoL) measures (p < 0.0001 – p = 0.0030), and VAS measures (p < 0.0001 – p = 0.038). External validation (n = 44) confirmed LAMDA outperformed SJC alone in discerning treatment intention and participant acceptable symptom state (PASS). 

Key learning: In this study, LAMDA, an ultrasound-derived composite disease activity measure integrating objective inflammation and patient-reported outcomes in SLE-related arthritis, offered improved sensitivity and responsiveness over conventional joint counts. Further validation is underway in randomized controlled trials.