Association between serum total cholesterol level and renal outcome in systemic lupus erythematosus

Abstract

Objective: To determine whether an elevated serum total cholesterol level in a first-available sample obtained at a systemic lupus erythematosus (SLE) clinic is associated with worse renal outcome in patients with SLE.

Methods: Survival analysis methods were used on prospectively gathered data on 1,060 patients with SLE who were registered in the University of Toronto Lupus Databank. The effect of total cholesterol and 15 additional variables on the outcomes of renal deterioration, end-stage renal disease (ESRD), and death was assessed using Cox proportional hazards methods.

Results: In 474 (45%) of the 1,060 patients, the total cholesterol level exceeded 5.2 mmoles/liter. In the entire study group, the median total cholesterol level was 5.1 mmoles/liter (range 1.6-17.1). During a mean followup period of 8.8 years, 93 patients (9%) experienced renal deterioration, 42 patients (4%) had ESRD, and 161 deaths occurred, 48 (30%) of which were associated with renal dysfunction (renal death), and 113 (70%) of which were not associated with renal dysfunction (nonrenal death). Kaplan-Meier survival estimates for each outcome were statistically significantly different between patients with normal versus those with elevated total cholesterol levels (cutoff 5.2 mmoles/ liter), with a worse outcome observed among those with an elevated total cholesterol concentration. In multivariate analyses, total cholesterol level (hazard ratio [HR] 1.17, 95 confidence interval [95% CI] 1.01-1.36), serum creatinine level (HR 1.06, 95% CI 1.04-1.07), proteinuria (HR 2.44, 95% CI 1.25-4.76), the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (HR 1.44, 95% CI 1.16-1.80), and corticosteroid dose (HR 1.01, 95% CI 1.00-1.02) were associated with renal deterioration. Significant predictors of ESRD were baseline proteinuria (HR 6.24, 95% CI 1.96-19.88) and serum creatinine level (HR 1.15, 95% CI 1.08-1.22). The total cholesterol level was correlated with death (HR 1.20, 95% CI 1.11-1.29), retaining statistical significance for renal death (HR 1.33, 95% CI 1.20-1.47) but not for nonrenal death (HR 1.12, 95% CI 0.99-1.25).

Conclusion: Those results indicate that an elevated serum total cholesterol level in a first-available sample obtained at an SLE clinic is associated with adverse renal outcomes and mortality.