Objective: To evaluate the prevalence, clinical associations, and outcome of antiphospholipid syndrome (APS) nephropathy in patients with systemic lupus erythematosus (SLE) and antiphospholipid antibodies (aPL) and in SLE patients without aPL.
Methods: Kidney biopsy specimens obtained from 81 patients with aPL (18 of whom had APS) and 70 patients without aPL were retrospectively examined for the presence of APS nephropathy. Clinical and serologic data obtained at the time of kidney biopsy and during a mean followup of 7 years were recorded. In cases for which serial kidney biopsy specimens were available, the evolution of APS nephropathy was examined.
Results: APS nephropathy existed in 39.5% of patients with aPL, compared with only 4.3% of patients without aPL. APS nephropathy was associated with both lupus anticoagulant and anticardiolipin antibodies. Among aPL-positive SLE patients, APS nephropathy was found in two-thirds of those with APS and in one-third of those without APS. A strong association between APS nephropathy and the presence of arterial thrombosis and livedo reticularis was noted. Patients with APS nephropathy had a higher frequency of hypertension and elevated serum creatinine levels at the time of kidney biopsy but did not have a higher frequency of renal insufficiency, end-stage renal disease, or death at the end of followup. Serial kidney biopsy specimens were available from 11 patients and showed progression of APS nephropathy lesions. During followup, manifestations of APS (especially arterial thromboses) developed more frequently in the SLE/non-APS patients with APS nephropathy than in those without APS nephropathy.
Conclusion: Among patients with SLE, APS nephropathy occurs almost exclusively in those with aPL, suggesting an important role of aPL in the pathogenesis of APS nephropathy. Patients with APS nephropathy develop hypertension, raised serum creatinine levels, and progression of histologic lesions, all of which are associated with a poor renal outcome. Manifestations of APS also tend to develop in these patients. APS nephropathy should be included in the APS classification criteria, and the use of appropriate anticoagulant therapy should be tested.