CUMULATIVE RATE OF RELAPSE OF LUPUS NEPHRITIS AFTER SUCCESSFUL TREATMENT WITH CYCLOPHOSPHAMIDE

Objective. To determine the cumulative rate of relapse of lupus nephri tis that has been treated successfully with cyclophosphamide (CYC), an d to estimate the association between time to relapse and demographic, clinical, laboratory, and treatment variables. Methods. This was an o bservational study of 48 systemic lupus erythematosus (SLE) patients w ho were treated successfully with CYC between 1979 and 1993 and follow ed up thereafter at 3 university hospitals, Demographic and clinical v ariables, laboratory data during the first month of nephritis, and the rapy-related variables were recorded from charts, Renal biopsy specime ns 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 compari sons of time to relapse were computed by log-rank test, Proportional h azards modeling was used to assess the combined effect of patient char acteristics that have been hypothesized to be prognostic factors. Resu lts. Nephritis relapsed in 11 patients, Previous hematologic disorder, arthritis or arthralgia, and tbe use of CYC in oral form were more fr equent in patients who had a relapse, The cumulative rate of relapse w as 25% and 46% at 5 years and 10 years, respectively, A significant un ivariate difference in time to relapse was found when patients were st ratified by time from diagnosis to initiation of CYC treatment (less t han or equal to 5 months versus >5 months; P = 0.02), By multivariate analysis, age <29 years at nephritis onset (relative risk [RR] 6.29, 9 5% 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 t o 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 tim e of nephritis onset are at increased risk of relapse.