Predictors of kidney disease progression in lupus patients initially presenting with mild renal involvement

Renal disease is a common serious manifestation among patients with systemic lupus erythematosus (SLE). However, the outcome and factors associated with kidney disease progression in SLE patients initially presenting with mild renal disease are not well known. To determine the factors associated with a decline in renal function in SLE patients initially presenting with mild lupus nephritis. A retrospective cohort of 61 patients with mild lupus nephritis was examined. All patients fulfilled the American College of Rheumatology criteria for SLE. Mild renal involvement was defined as glomerular filtration rate (GFR) ≥90 ml/min in the presence of active urinary sediment. GFR was estimated using the Cockcroft-Gault equation. Demographic, clinical parameters and pharmacologic treatments were evaluated at renal onset. A decline in renal function was defined as GFR <90ml/min. Kaplan-Meier survival curves were estimated and a Cox proportional hazards model was constructed. 90.2% of patients were females. Mean age at renal onset was 29.3 ± 12.1 years. Mean follow-up was 5.1 ± 3.4 years. 62.3% of the patients had a decline of GFR during the disease course. In the Cox multivariate analyses, age ≥40 (HR = 5.65, 95% CI 2.31-13.83), low C4 level (HR = 3.81, 95% CI 1.66-8.73), and proteinuria ≥0.5g/day (HR = 2.63, 95% CI 1.14-6.08) were associated with an earlier decline in GFR. The present study showed that most SLE patients with mild-onset kidney disease had a decline in GFR. Age (≥40 years), proteinuria and low C4 complement levels were predictors of renal disease progression.