Extrarenal disease activity in systemic lupus erythematosus is not suppressed by chronic renal insufficiency or renal replacement therapy.

OBJECTIVE: To assess whether chronic renal impairment (CRI) and/or renal replacement therapy (RRT) in systemic lupus erythematosus (SLE) are associated with reduced extrarenal SLE activity.
METHODS: This was a retrospective cohort analysis of patients with SLE who are followed at the University of Toronto Lupus Clinic. Patients with SLE were studied in 2 stages; chronic renal insufficiency (defined as a serum creatinine > 200 mumol/1 for > 6 months) and following the institution of dialysis therapy. Controls consisted of the next 2 age and sex matched patients in the clinic with a history of lupus nephritis who had not developed renal insufficiency. We assessed the flare rate (an increase in nonrenal SLEDAI > or = 1.0) for patients and controls in the first 12 months of followup at the clinic in each stage.
RESULTS: Twenty-one patients, 17 female and 4 male, were followed through 25 episodes of CRI or RRT as were 50 controls. In the CRI stage (n = 12), flares occurred in 8 (67%) within one year compared to 14 (58%) of 24 controls (p = NS). In the RRT stage (n = 13), flares occurred in 7 (54%) compared to 16 (62%) of 26 controls (p = NS). The magnitude as well as the characteristics of the flares did not differ between patients and controls in either stage.
CONCLUSION: Patients with SLE who develop CRI, or who receive RRT, continue to display evidence of ongoing extrarenal disease activity. Such patients require careful longterm followup for management of their extrarenal disease.