A 5-Year Retrospective, Observational Study Assessing Rheumatoid Arthritis Disease Outcome Measures to Characterize Systemic Lupus Erythematosus Burden in the USA

Introduction: We evaluated the use of rheumatoid arthritis (RA) disease measures in patients with systemic lupus erythematosus (SLE) in a US community-based rheumatology physician network over 5 years.

Methods: This retrospective, observational cohort study (GSK Study 213818) of patients with SLE utilized electronic medical records (01 January 2010-31 December 2019) from the United Rheumatology Normalized Integrated Community Evidence database. The index was the date of first SLE diagnosis recorded in the database; the observation period was 5 years post-index. RA disease measures evaluated were: Pain Index, Multi-Dimensional Health Assessment Questionnaire (MD-HAQ), Patient Global Assessment (PtGA), Physician Global Assessment (PGA), Swollen Joint Count (SJC), Tender Joint Count (TJC), Routine Assessment of Patient Index Data 3 (RAPID3), Clinical Disease Activity Index (CDAI), Simplified Disease Activity Index (SDAI), and Disease Activity Score 28 (DAS-28). The number of patients with measures utilized, the score on each measure, and proportion of patients per disease activity category were assessed.

Results: Overall, 5990 patients with SLE were included. The most frequently used measures were Pain Index, SJC, TJC, MD-HAQ, PtGA, RAPID3, and PGA (cumulative use over Years 1-5: 23.9-71.3%). For all measures, frequency of use was lowest in Year 1, followed by a general increase from Year 1 to Year 5. Scores remained relatively stable for most measures, and the proportion of patients in remission or with low/moderate disease activity per RAPID3 increased.

Conclusion: RA disease measure utilization in SLE was generally infrequent but increased over time. Pain Index and MD-HAQ were the most commonly applied cumulatively across 5 years of follow-up. The rationale for the increased use of these measures in SLE over time requires further exploration. In the absence of a clinically applicable SLE-specific measure, the use of RA measures, for example in conjunction with SLE measures, may provide an alternative approach for measuring disease activity, representing an opportunity to improve patient outcomes.