OP0285 ANTIPHOSPHOLIPID SYNDROME NEPHROPATHY IS ASSOCIATED WITH SEVERE CLINICAL SUBSETS AND TRIPLE aPL POSITIVITY. A SINGLE-CENTER RETROSPECTIVE STUDY
Authors: A. Hoxha, N. Perin, M. Lovisotto, A. Calligaro, T. Del Ross, M. Favaro, M. Tonello, M. Zerbinati, A. Doria, P. Simioni
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Anti-phospholipid syndrome (APS) might involve both arterial and venous kidney vasculature, leading to various clinical manifestations, which can lead to end-stage kidney disease. However, the prevalence of renal involvement in antiphospholipid antibody syndrome and its clinical and autoantibody features are poorly understood. <h3>Objectives:</h3> To identify predictor risk factors associated with APS nephropathy, we assess the frequency of nephropathy in antiphospholipid syndrome (APS) and evaluate the association with different laboratory and clinical APS subsets. <h3>Methods:</h3> We conducted a retrospective single-center cohort study. The medical records of 274 patients, 231 (84.3%) female and 43 (15.7%) males with a mean (±SD) age at diagnosis of 37.8 (±11.5) years, followed from 1990 to 2021, were reviewed. An ad hoc electronic data capture was set up to register the study cohort's demographic, laboratory, and clinical characteristics. All the diagnoses of APS made before the Sydney Consensus Conference were revised, and the patients who did not fulfill APS classification criteria were excluded. Renal involvement was defined as the presence of renal insufficiency (serum creatinine 1.4 mg/dl) and/or of urinary abnormalities (proteinuria 0.3 g/d with or without microscopic hematuria on two separate occasions, in the absence of urinary infection and or the presence of renal biopsy showing histopathologic lesions compatible with APS. <h3>Results:</h3> Both thrombosis and pregnancy morbidity (TOAPS) were found in 38 (13.9%) patients, a history of thrombosis alone (TAPS) was present in 140 (51.1%) and 96 (35%) had pregnancy morbidity alone (OAPS). A single, double, or triple antiphospholipid antibodies (aPL) positivity was recorded, respectively in, 82 (29.9%), 78 (28.5%), and 114 (41.6%) of the patients. Following a mean (±SD) follow-up of 208.4 (±91.7) months, a total of 36 (13.1%) APS nephropathy was recorded. APS nephropathy was found in 36/274 (13.1%) of primary APS patients; in 18/36 (50%) residual chronic renal failure and in 4/36 (11.1%) need renal transplantation. The prevalence of APS nephropathy was significantly higher in TOAPS and TAPS compared to OAPS, respectively p=0.0002 and p=0.0012, while there was no difference between TOAPS and TAPS. Moreover, patients with microangiopathy involvement presented a significantly higher rate of APS nephropathy than those without microangiopathy manifestations (45.5% vs 2.9%, p&lt;0.0001). Furthermore, triple aPL positivity was significantly associated with APS nephropathy compared to single and double aPL positivity, respectively p&lt;0.0001 and p&lt;0.001. At the same time, there was no significance between single and double aPL positivity. <h3>Conclusion:</h3> Overall, our data showed that APS nephropathy was associated with high morbidity. Higher risk clinical and/or autoantibody APS profiles, such as thrombosis and triple aPL positivity, could predict APS nephropathy. This is important when approaching APS patients and tailoring the treatment. These findings should be considered when counseling APS patients and help guide clinicians' therapeutic decisions. <h3>REFERENCES:</h3> [1] De Simone E, Sciascia S, Fenoglio R, Oddone V, Barreca A, Roccatello D. Antiphospholipid Syndrome and Kidney Involvement. Kidney Blood Press Res. 2023;48(1):666-677. doi: 10.1159/000529229. <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> <b>None declared.</b>