Comparison of renal disease severity and outcome in patients with primary antiphospholipid syndrome, antiphospholipid syndrome secondary to systemic lupus erythematosus (SLE) and SLE alone

Objective. To ascertain the clinical presentation, histopathology and outcome of renal involvement in patients with primary antiphospholipid syndrome (PAPS), antiphospholipid syndrome secondary to systemic lupus erythematosus (SAPS) and systemic lupus erythematosus alone. Method. A retrospective analysis was undertaken of 20 patients with PAPS, 25 patients with SAPS and 275 patients with systemic lupus erythematosus to ascertain the frequency and pattern of renal involvement. Results. Renal involvement was found most frequently in patients with SAPS, in whom it occurred in 68% of patients. Renal disease was equally common in patients with PAPS and systemic lupus erythematosus alone where it was seen in 30% of patients. Patients with systemic lupus erythematosus most frequently presented with nephrotic syndrome due to glomerulonephritis, whereas those with PAPS and SAPS were more likely to present with hypertension and reduced glomerular filtration rate. No patients with PAPS developed end‐stage renal failure compared with 5.9% of patients with SAPS and 16.9% of patients with systemic lupus erythematosus alone; 23.5% of patients with SAPS died compared with 15.7% of patients with systemic lupus erythematosus alone and no patients with PAPS. Conclusion. Renal involvement is a major feature of both PAPS and SAPS, where renal thrombosis frequently leads to reduced glomerular filtration rate and hypertension. One‐third of patients with systemic lupus erythematosus alone develop glomerulonephritis leading to renal disease which most commonly presents with nephrotic syndrome. Patients with PAPS were less likely to develop end‐stage renal failure or die during the follow‐up period.