ABSTRACT
Objective:To explore the clinical and histopathologic features of lupus nephritis (LN) patients with positive antineutrophil cytoplasmic antibody (ANCA), so as to provide more theoretical basis to recognize and treat this disease.Methods:Clinical data of biopsy-proven LN patients with ANCA test in the First Affiliated Hospital of Sun Yat-sen University from November 1, 2002 to September 11, 2020 were collected and analyzed retrospectively. The difference of clinical data, laboratory examination, and pathological examination of renal biopsy between ANCA-positive group and ANCA-negative group. The clinicopathological characteristics between different ANCA serotypes were compared.Results:A total of 1 304 patients with LN confirmed by renal biopsy and ANCA test results were enrolled. Eighty ANCA-positive patients from 1 304 LN patients were screened. There are 55(68.8%) ANCA-positive LN patients with positive anti-myeloperoxidase antibodies (MPO). There were 14(17.5%) ANCA-positive LN patients with positive anti-proteinase 3 antibodies (PR3), and 11(13.8%) ANCA-positive patients with double positive antibodies of MPO and PR3. ANCA-positive LN patients had significantly higher serum creatinine [135.5(68.0, 361.8) μmol/L vs 88.0(64.0, 165.0) μmol/L, P=0.004] and blood urea nitrogen [12.35(6.35, 21.18) mmol/L vs 8.60 (5.50, 15.70) mmol/L, P=0.026] as well as lower estimated glomerular filtration rate [45.70(13.83, 84.10) ml·min -1·(1.73 m 2) -1 vs 66.75(38.43, 96.22) ml·min -1·(1.73 m 2) -1, P=0.001] than ANCA-negative patients (stratified sampling of 160 patients). ANCA-positive LN patients had higher chronicity index than ANCA-negative LN patients [3(2, 7) vs 2(0, 5), P=0.006]. There were statistically significant difference in hemoglobin, serum creatinine and estimated glomerular filtration rate among ANCA-positive group, ANCA-negative group, and MPO-ANCA and PR3-ANCA double positive group. MPO-ANCA and PR3-ANCA double positive LN patients had the lowest hemoglobin and estimated glomerular filtration rate, and highest serum creatinine among the three groups (all P<0.05). Conclusions:ANCA-positive LN patients have worse renal function and higher renal histological chronicity index than ANCA-negative LN patients, especially for patients with double positive MPO-ANCA and PR3-ANCA. More stringent monitoring and therapy may be needed in this subgroup of LN patients.