Background: Previous studies have documented the high frequency of thrombosis and fetal loss in patients with lupus nephritis and antiphospholipid (aPL) antibodies, but there is little information on the impact of aPL antibodies on the outcome of lupus nephritis. The aims of this study are to evaluate the prevalence of aPL antibodies in patients with lupus nephritis and assess their prognostic value for thrombosis and pregnancy morbidity and impact on long-term renal outcome.
Methods: One hundred eleven patients with lupus nephritis followed up for a mean of 173 +/- 100 months were tested regularly for immunoglobulin G (IgG) and IgM anticardiolipin antibodies and lupus anticoagulant.
Results: The overall prevalence of aPL antibodies was 26%. In follow-up, 79% of aPL antibody-positive patients experienced thrombotic events and/or fetal losses, and aPL antibodies were associated significantly with arterial or venous thrombosis (P = 0.00001), pregnancy morbidity (P = 0.045), thrombocytopenia (P = 0.0015), and persistent arterial hypertension (P = 0.028). aPL antibodies were significantly more frequent in patients with biopsy-proven membranous lupus nephritis (P = 0.01). A strong association between aPL antibodies and the development of chronic renal insufficiency in the long-term outcome also was found (P = 0.01). With multivariate analysis, aPL antibody positivity (P = 0.02), high plasma creatinine level at presentation (P = 0.01), and chronicity index (P = 0.00004) were independent predictors of chronic renal function deterioration.
Conclusion: Detection of aPL antibodies in patients with lupus nephritis is useful not only to identify patients at risk for vascular and obstetric manifestations, but also for their potential deleterious impact on renal outcome.