Pathological severity determines the renal recovery for anti-myeloperoxidase antibody-associated vasculitis requiring dialysis at disease onset: a retrospective study

Abstract

Background: Many patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) need dialysis at disease onset due to severe kidney injury. Determining whether they can become dialysis independent is an important clinical assessment.

Methods: Forty kidney biopsy-proved myeloperoxidase (MPO)-ANCA associated AAV patients who required dialysis at disease onset were enrolled. Relationships between laboratory and pathological characteristics and prognoses were analyzed.

Results: Twenty-five patients obtained dialysis independence within 3 months, while the other 15 patients remained dialysis dependent. No sclerotic class was identified among the 40 patients. Only two biopsies exhibited focal class diagnoses and both these patients recovered their renal function. The renal recovery rate of the 20 patients with mixed class was significantly lower than that of the 18 patients with crescentic class (40.0% vs. 83.3%, p = 0.006). Receiver operating characteristics (ROC) curves showed fibrous crescent+global glomerulosclerosis greater than 32.6% was a strong predictor of dialysis dependence with a sensitivity of 93.3% and specificity of 88.0%. When the percentage of fibrous crescent+global glomerulosclerosis exceeded 47.9%, dialysis independence was not possible. Correlation analysis indicated that platelet counts were negatively correlated with the percentage of fibrous crescent+global glomerulosclerosis (R = -0.448, p = 0.004). Most patients with increased platelets (84.62%) obtained renal recovery. Compared with methylprednisolone pulse therapy, plasma exchange accelerated renal recovery (29.4 ± 15.6 vs. 41.4 ± 11.7 days, p = 0.039).

Conclusions: For MPO-ANCA AAV who required dialysis at disease onset, crescentic and mixed classes accounted for the majority of patients in our cohort. The renal outcome of mixed class patients was worse than that of crescentic class. A high proportion of fibrous crescent+global glomerulosclerosis is a predictor of dialysis dependence. Increased platelet count is associated with active and reversible renal lesions.

Keywords: Antineutrophil cytoplasmic antibody; Dialysis; Histopathologic classification; Myeloperoxidase; Renal biopsy.

Fig. 1

Patients selection flowchart. A total of 244 patients with AAV were diagnosed. Only 7 patients were PR3-ANCA positive and were excluded. Among 237 patients with MPO-ANCA, 217 patients had kidney injury, but 102 patients did not receive kidney biopsy. Patients without kidney biopsy and patients who died before obtaining dialysis independence within 3 months were also excluded. At last, 40 patients were included in this study

Fig. 2

Kidney prognosis of patients with different histopathologic classification. a The renal recovery rate of patients with focal, crescentic or mixed class. b The estimated glomerular filtration rate (eGFR) at admission, 3 months after therapy and 1 year after therapy of patients with focal, crescentic or mixed class. c Comparison of the combined end point (Death and ESRD) among patients with different histopathologic classification. The longest follow-up time was 36 months

Fig. 3

Receiver operating characteristic (ROC) curves of different histopathologic indexes including the percentages of: normal glomeruli (a), cellular crescent (b), fibrous crescent (c), global glomerulosclerosis (d) and fibrous crescent+global glomerulosclerosis (e). Area under the curve (AUC) was calculated to distinguish patients with renal recovery from patients remaining on dialysis

Fig. 4

Relationship between platelet counts and histopathologic indexes and relationship between platelet counts and prognosis. a Correlation between platelet counts and the percentages of fibrous crescent+global glomerulosclerosis. b Comparison of the difference of histopathologic classification between patients with normal and increased platelets. Increased platelets were diagnosed when platelets were more than the upper limit 300 × 10⁹/L. c Comparison of the proportions of patients with fibrous crescent+global glomerulosclerosis more than cut-off value (32.6%) between patients with normal and increased platelets. d Comparison of the proportions of renal recovery within 3 months between patients with normal and increased platelets