Cumulative rate of relapse of lupus nephritis after successful treatment with cyclophosphamide

Abstract

Objective: To determine the cumulative rate of relapse of lupus nephritis that has been treated successfully with cyclophosphamide (CYC), and to estimate the association between time to relapse and demographic, clinical, laboratory, and treatment variables.

Methods: This was an observational study of 48 systemic lupus erythematosus (SLE) patients who were treated successfully with CYC between 1979 and 1993 and followed up thereafter at 3 university hospitals. Demographic and clinical variables, laboratory data during the first month of nephritis, and therapy-related variables were recorded from charts. Renal biopsy specimens were retrieved and analyzed by a pathologist. Relapse of nephritis was the outcome of interest. Descriptive analysis of patients who did and those who did not have a relapse was performed by chi-square test, Fisher's exact test, and Wilcoxon 2-sample test. The cumulative rate of relapse was computed using the actuarial method. Univariate comparisons of time to relapse were computed by log-rank test. Proportional hazards modeling was used to assess the combined effect of patient characteristics that have been hypothesized to be prognostic factors.

Results: Nephritis relapsed in 11 patients. Previous hematologic disorder, arthritis or arthralgia, and the use of CYC in oral form were more frequent in patients who had a relapse. The cumulative rate of relapse was 25% and 46% at 5 years and 10 years, respectively. A significant univariate difference in time to relapse was found when patients were stratified by time from diagnosis to initiation of CYC treatment (< or = 5 months versus > 5 months; P = 0.02). By multivariate analysis, age < 29 years at nephritis onset (relative risk [RR] 6.29, 95% confidence interval [95% CI] 1.13-34.94, P = 0.03) and delay of > 5 months from onset of nephritis to initiation of CYC therapy (RR 3.66, 95% CI 1.06-12.63, P = 0.04) were independently associated with time to relapse.

Conclusion: A selected population of SLE patients may have long-term remission of renal disease following successful CYC therapy. Patients in whom CYC treatment is delayed or who are young at the time of nephritis onset are at increased risk of relapse.