Predictors of incident proteinuria among patients with SLE

To identify fixed and time-varying predictors of incident proteinuria.

This analysis was based on patients who did not have a history of diabetes and who did not have a prior episode of renal involvement. We defined an incident case of proteinuria as two or more measures of urine protein to creatinine ratio (or 24-hour protein measure) greater than 0.5 in two visits separated by more than 30 days and less than 180 days. We estimated rates of incident proteinuria in subgroups of patients with lupus defined by time-invariant and time-varying predictors.

Among 895 patients included in the analysis, 840 (94%) were female, and 518 (58%) were Caucasian, 304 (34%) African-American, with mean age of 42 years at the start of follow-up. We observed 57 incident cases of proteinuria over a span of 4669 person-years of cohort follow-up. The overall rate of incident proteinuria was 12.2 per 1000 person-years. The rate was significantly lower among those of older age, and higher among those who were not Caucasian. In those with a very low C3 measure in a previous cohort visit, the rate was increased by a factor of 16.1 and in those with a very low C4 by 16.3. The rate among those prescribed hydroxychloroquine or ACE inhibitors/ARB was similar to those not on them.

Older patients with SLE are at low risk for developing proteinuria. There was not strong evidence that hydroxychloroquine or angiotensin-converting-enzyme (ACE) inhibitor reduced the risk of proteinuria. The highest rates of incident proteinuria were among those with recent low complement.