Background/Purpose: Renal disease is a critical concern of physicians counseling lupus patients regarding pregnancy. In patients without a history of kidney disease, does pregnancy increase the risk of first time involvement? In patients with previous renal disease, does pregnancy raise the likelihood of a renal flare? In both cases, prediction of outcome is challenging in a clinically stable patient with serologic activity (abnormal anti-dsDNA antibodies coupled with low complements). Accordingly, our objective was to assess serologic activity as a predictor of renal flares during pregnancy in patients with less than 1 gram of protein at enrollment in a large, prospective, multicenter, mutiethnic study.

Methods: The PROMISSE Study (Predictors of pRegnancy Outcome: BioMarkers In antiphospholipid antibody Syndrome and Systemic Lupus Erythematosus) prospectively evaluated 391 pregnant SLE patients. Exclusion criteria were multi-fetal pregnancy, prednisone >20mg/d, proteinuria >1gm/24hr, and creatinine >1.2mg.dL. A renal flare was defined by proteinuria increase of >500mg with or without hematuria and/or red blood cell casts. Of the 391 patients, 121 (31%) had preexisting renal disease as defined by ACR SLE criteria and/or a renal biopsy in 53 of whom 4% were Class I or II, 62% were Class III or IV, 13% were Class III/IV & V, and 21% were Class V. Overall at enrollment, 17% had only positive anti-dsDNA, 12% had only hypocomplementemia, 20% had both, and 51% were normal for both parameters.

Results: 16 renal flares occurred in 121 patients with previous renal disease. All had proteinuria, 5 (31%) had hematuria, and 1 (6%) had red blood cell casts. There were no differences between biopsy classes for patients with and without renal flares. Of the 29 patients with a history of renal disease and both anti-dsDNA and hypocomplementemia, 5 (17%) had a renal flare. In 44 patients with either serology alone, 7(16%) had renal flares. In 48 patients with neither serology, 4 (8%) had renal flares. 5 patients were treated with increased prednisone. 3 treated patients and 2 untreated patients developed pre-eclampsia. Other adverse pregnancy outcomes included 3 (19%) fetal/neonatal deaths and 2 (13%) with SGA <5^th %ile in the 16 patients with renal flares. In 270 patients with no history of kidney disease, only 3 renal flares occurred. Of the 50 patients with no history of renal disease and both anti-dsDNA and hypocomplementemia, 2 (4%) had new onset proteinuria; one was treated and developed pre-eclampsia. In 150 patients with neither serology, 1 had new onset proteinuria which was treated and had SGA <5^th %ile. None of 70 with either serology alone had renal flares.

Conclusion: These data provide evidence that clinical quiescence or stability at the time of conception favors good renal outcomes during pregnancy regardless of serologic activity. Increased proteinuria (not uniformly requiring prednisone) occurred in 13% of patients with previous renal disease and 1% of those without a history of kidney disease. Thus, in counseling women with lupus who are contemplating pregnancy, abnormal serology alone should not lead to advising against pregnancy even in patients with previous renal disease.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/abnormal-serologies-in-the-absence-of-clinical-activity-do-not-predict-new-or-recurrent-lupus-nephritis-during-pregnancy/