[Impact of kidney biopsy on the management of patients in the rheumatology department: retrospective study].

BACKGROUND: Kidney involvement is a common manifestation of the systemic autoimmune rheumatic diseases. Kidney biopsy is the gold standard for the diagnosis of kidney diseases, however this method has not yet become the standard-of-care in rheumatology practice. AIM: To assess the diagnostic value of kidney biopsy in the management of patients of the rheumatology department. MATERIALS AND METHODS: In this retrospective observational study we analyzed the medical documentation including kidney morphology findings in the patients of the Department of Rheumatology at Tareev Clinic of Internal Diseases. All patients included in the research had signs of kidney involvement and had undergone needle biopsy of the kidney or re-evaluation of the kidney tissue received previously. RESULTS: From June 2016 to October 2021, 3110 patients were admitted to the rheumatology department. Among them 63 (2%) underwent kidney biopsy and were included in the study. Twenty (32%) were male. Mean age was 42.513.9 years. The most common preliminary diagnoses before kidney biopsy were ANCA-associated vasculitis (n=17), systemic lupus erythematosus (n=12), and AA-amyloidosis associated with inflammatory joint diseases (n=7). In 14 (27%) patients diagnosis was unspecified at the time of biopsy. Among 49 patients with established preliminary diagnosis morphological findings were in line 38 (78%) with the pre-liminary diagnosis. However, in 11 (22%) patients morphological findings resulted in the change of the diagnosis. In all 14 patients with unspecified condition kidney biopsy helped to establish clinical diagnosis. Ultrasound evaluation demonstrated hematoma formation in 18 (31%) patients, and among them two required blood component transfusions. CONCLUSION: Our study demonstrates significant value and safety of kidney biopsy in the patients with autoimmune rheumatic conditions. We suggest that kidney biopsy should be implemented in the management of this category of patients.

Relationship between serologic profile (ANCA type) and clinical features of renal involvement in ANCA-associated vasculitides.

AIM: To compare the frequency, clinical features and outcomes of renal involvement in ANCA-associated vasculitides (AAV) in patients with antibodies against proteinase-3 (pr3-ANCA) and myeloperoxidase (MPO-ANCA). MATERIALS AND METHODS: In our retrospective study we enrolled 264 patients, 94 males and 170 females, median age 53 [36; 62] years. Among them 157 were pr3-ANCA positive and 107 were MPO-ANCA positive. AAV was diagnosed according to ACR criteria and Chapel Hill consensus conference definition (2012). Median follow up was 44 [18; 93] months. We assessed baseline BVAS and VDI by the end of the follow up. Serum creatinine (sCr), estimated glomerular filtration rate (eGFR), hematuria and daily proteinuria were estimated. Diagnosis and stage of chronic kidney disease (CKD) and acute kidney injury (AKI) were established according to KDIGO guidelines (2012) and Scientific Society of Russian Nephrologists (2016). RESULTS: Renal involvement was present in 181 (68.6%) patients, and its frequency was similar in pr3-ANCA and MPO-ANCA subgroups. Patients with MPO-ANCA developed rapidly progressive glomerulonephritis and hypertension significantly more often than patients with pr3-ANCA: 50.7% vs 35.6% (p=0.049) and 46.1% vs 29.8% (p=0.029) respectively. At disease onset, median sCr was significantly higher and eGFR was significantly lower in patients with MPO-ANCA (p<0.05). 1-year and 5-year renal survival rates were similar in pr3-ANCA-positive (93.9% and 87.4% respectively) and MPO-ANCA positive patients (87.4% and 83.1% respectively). Median BVAS and VDI scores were significantly higher in pr3-ANCA subgroup. The number of patients who developed AAV relapse during 1-year follow up was also significantly higher in pr3-ANCA subgroup. The frequency of eye and ENT involvement was significantly higher in pr3-ANCA positive patients than in MPO-ANCA-positive patients. CONCLUSION: The frequency of extrarenal manifestations, clinical features of renal involvement and relapse rate are associated with AAV serotype.

Clinical features of kidney involvement in microscopic microscopic polyangiitis.

AIM: To evaluate clinical features and outcomes of renal involvement in patients with microscopic polyangiitis (MPA). MATERIALS AND METHODS: We enrolled 99 patients with MPA, diagnosed in accordance with the algorithm of the European Medicines Evaluation Agency (EMEA) and the Chapel Hill consensus conference definition (2012). Serum creatinine (sCr), estimated glomerular filtration rate (eGFR), hematuria and proteinuria were estimated. Frequency of rapidly progressive renal failure (a twofold increase in the sCr level in ≤3 months) was regarded as the clinical equivalent of rapidly progressive glomerulonephritis (RPGN). RESULTS: Renal involvement was present in 92 (92.9%) patients. RPGN developed in 51 (55,4%) patients. The most common features of kidney involvement were hematuria and subnephrotic proteinuria. Arterial hypertension was revealed in 32 (34.7%) patients and was associated with RPGN (p<0.004). End-stage renal disease (ESRD) developed in 11 (11.9%) patients. Despite effective induction therapy disease relapses occurred in 20 (21.1%) patients during the 1st year, including renal relapses in 12 (13.3%) cases. During 5-year follow up 34 (37.1%) patients developed disease relapses, including renal relapses in 22 (24.4%) patients. CONCLUSION: Renal involvement is one of the most common manifestations of MPA with a high frequency of RPGN. More than one third of patients develop disease relapses despite adequate therapy.