Li-Yuan Xie, Xian-Ying Qiu, Hao-Miao Zhang, Chen-Xi Cai, Di Zhang, Peng-Cheng Xu, Jun-Ya Jia
For ANCA-positive SLE patients, renal injury may be caused by LN, LN combined with AAGN, or even isolated AAGN. So renal biopsy plays a crucial role in guiding the accurate choice of therapeutic strategy. Further studies are required owing to the heterogeneity of case sources.
BACKGROUND: Antineutrophil cytoplasmic antibody (ANCA) positivity is not uncommon in patients with systemic lupus erythematosus (SLE), however, the diagnosis of concurrent SLE and ANCA-associated vasculitis (AAV) is challenging because SLE tends to mask the clinical manifestations of AAV. Since the kidney is the most frequently affected organ in AAV, we consider that SLE patients with concurrent renal biopsy-proven AAGN warrant the greatest clinical attention.
METHODS: We enrolled two patients with newly diagnosed SLE and renal biopsy-proven AAV glomerulonephritis (AAGN). After a literature search, another 57 similar patients were identified. Then the clinical characteristics of these patients were analyzed.
RESULTS: Including the two newly reported patients, a total of 51 female and 8 male patients were included. Compared with patients with AAGN alone, patients with combined lupus nephritis (LN) and AAGN had higher SLEDAI scores [14.00 (10.00-18.00) vs. 5.00 (2.50-12.50), P = 0.028], and the 24-h urinary protein level tended to be higher in the LN + AAGN group [3.10 (1.70, 6.69) g/d vs. 1.66 (0.88, 2.15) g/d, p = 0.066]. Patients with elevated C-reactive protein (CRP) levels had lower SLEDAI scores (P = 0.021), higher leukocyte counts (P = 0.005). Patients with elevated leukocyte counts had the lowest proteinuria levels (P = 0.029) but the highest incidence of pulmonary hemorrhage (P = 0.016) compared to those with normal or decreased counts. Low complement 4 and high proteinuria levels were associated with high SLEDAI scores (P = 0.041 and P = 0.027, respectively). Patients who progressed to end-stage renal disease had a higher mortality than those who achieved renal remission (P < 0.001). Renal prognosis did not differ between LN + AAGN and AAGN alone groups (23.1% vs. 25.0%, p = 1.000). The mortality rate was 23.1% in the LN + AAGN group and 5.0% in the AAGN alone group (P = 0.166).
CONCLUSION: For ANCA-positive SLE patients, renal injury may be caused by LN, LN combined with AAGN, or even isolated AAGN. So renal biopsy plays a crucial role in guiding the accurate choice of therapeutic strategy. Further studies are required owing to the heterogeneity of case sources.