Time to lupus nephritis: impact of gender and ethnicity

Objective

There is a paucity of literature regarding the time to development of nephritis among SLE patients. Our goal was to define this important parameter for a large multi-ethnic cohort, with an emphasis on the impact of gender and ethnicity.

Methods

779 SLE patients with disease satisfying the ACR criteria were classified as non-nephritis or definite nephritis patients based on questionnaire and comprehensive medical record review. Patients classified with definite nephritis fulfilled the criteria of proteinuria (> 0.5 g per 24 hrs), active sediment, or renal biopsy consistent with SLE. 716 (92%) were female. The ethnic distribution was: Caucasian 453 (58.2%), Hispanic 123 (15.8%), Asian 97 (12.4%), African American 75 (9.6%), and other 36 (4.6%). The annual rates of developing nephritis among different gender and ethnic subgroups were derived using Kaplan-Meier estimates.

Results

The table shows gender and ethnicity based Kaplan-Meier estimates of the proportion of patients with nephritis at designated time intervals. The curves are significantly different for males vs. females and Caucasians vs. non-Caucasians based on the log-rank test. The curves for Hispanic, Asian and African American subgroups did not differ significantly.

Table 1

Conclusions

These results are a significant contribution to the data regarding time to development of nephritis in SLE, and emphasize the important influence gender and ethnicity.