Effect of Disease Activity on Organ Damage Progression in Systemic Lupus Erythematosus: University of Toronto Lupus Clinic Cohort

Objective: To examine the role of disease activity on organ damage over 5 years in patients with active systemic lupus erythematosus (SLE) despite standard of care.

Methods: This analysis of the University of Toronto Lupus Clinic cohort assessed organ damage [measured by Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI)] in patients with active SLE [SLE Disease Activity Index 2000 (SLEDAI-2K) ≥ 6], using Cox proportional time-independent hazard models. Subgroup analyses were conducted in patients with SLEDAI-2K 6 or 7, 8 or 9, and ≥ 10 at baseline, and in the overall study population by steroid dose at study entry (< 7.5 vs ≥ 7.5 mg/day).

Results: Among the overall study population (n = 649), SDI progression was observed in 209 (32.2%) patients over the 5-year follow-up period. Mean SDI change in patients with a score > 0 was generally consistent across all SLEDAI-2K subgroups. Multivariable analyses identified age at study start (HR 1.03, < 0.0001), steroid dose (HR 2.03, < 0.0001), immunosuppressants (HR 1.44, = 0.021), and SLEDAI-2K (subgroup analyses HR 1.64-2.03, = 0.0017 to < 0.0001) as the greatest risk factors for SDI progression, while a study start date after the year 2000 had a protective effect on SDI progression compared with a start date prior to the year 2000 (HR 0.65, = 0.0004).

Conclusion: Patients within the higher SLEDAI-2K subgroups at study entry or receiving high doses of steroids were more likely to have organ damage progression.