Antiphospholipid syndrome nephropathy (APSN) in patients with lupus nephritis: a retrospective clinical and renal pathology study

Data about clinical-laboratory features and outcome of antiphospholipid syndrome nephropathy (APSN) in the course of lupus nephritis (LN) are scarce. To determine prevalence, clinical correlations and outcome of APSN in patients with LN, retrospective analysis of renal specimens and review of medical records from 48 LN patients were performed. APSN was found in 12/48 (25 %) of LN. Positivity for lupus anticoagulant (LAC) and double antiphospholipids positivity [LAC plus anticardiolipin (aCL)] were significantly more frequent in APSN-LN (p = 0.02 and p = 0.01, respectively) than in LN, while single aCL positivity was not. Overt antiphospholipid syndrome appeared more frequent in patients with APSN-LN (p = 0.05). There were no statistically significant differences between APSN-LN and LN in the proportion of each World Health Organization class of LN (with the exception of a trend toward fewer Class III LN in APS-LN) and in the systemic lupus erythematosus (SLE) disease duration and severity. At the time of renal biopsy, patients with APSN-LN had median serum creatinine levels significantly higher than patients with LN [1.45 (0.6-6.6) vs. 1.00 (0.7-3.0), p = 0.02]. Double antiphospholipid positivity was the only variable significantly associated with APSN-LN at multivariate regression analysis (OR 8, 95 % CI 1.7-37, p = 0,008). APSN-LN and LN did not differ significantly as regards the rate of complete (25 vs. 19.4 %, p = 0.72) and partial treatment response (25 vs. 29 %, p = 0.82) at 6 months and the progression to end-stage renal disease after a median follow-up of 8.1 ± 3.6 years (16.6 vs. 13.8 %, p = 0.82). APSN was demonstrated in a quart of LN, appeared to be independent from underlying LN class and SLE severity, and did not seem to confer a worse prognosis to LN. The findings of higher creatinine and more interstitial fibrosis in APSN should be confirmed in future prospective larger studies.