Histological and clinical predictors of early and late renal outcome in ANCA-associated vasculitis.
BACKGROUND
Renal involvement remains a major determinant in antineutrophil cytoplasmic autoantibody-associated small vessel vasculitis (AASV). While some patients may develop persistent renal damage, others have a favourable outcome.


METHODS
To identify patients at risk for poor renal outcome, we evaluated 95 renal biopsies (67 initial biopsies and 28 repeat biopsies) of 67 patients with AASV for the presence and extent of active (AI) and chronic (CI) lesions, retrospectively. AI, CI, levels of proteinuria and dose of cyclophosphamide (CYC) were related to renal outcome.


RESULTS
Recovery of renal function in patients initially dialysis dependent was associated with a lower CI compared with patients who remained on dialysis (P<0.001), while AI did not differ significantly. In these patients, age <65 years revealed a positive predictive value of 85% for renal function recovery. Patients initially requiring dialysis exhibited a higher AI and CI compared with those who did not. Renal function in long-term follow-up correlated with CI and the amount of proteinuria. This relationship increased with time, exhibiting at 4 years a correlation coefficient of 0.607 for CI (P<0.01) and of 0.775 for proteinuria (P<0.001). Follow-up biopsies showed a more pronounced CI compared with initial biopsies (P<0.001). None of the investigated initial parameters was predictive for renal relapse. However, there was a relationship between dose and duration of CYC and time to relapse. Compared with the initial biopsy, repeat biopsies of eight patients with a creeping serum creatinine in clinical remission showed a decrease of AI (P<0.001) while CI increased rapidly. These patients also had less initial CYC (NS).


CONCLUSIONS
These data suggest that in AASV, evaluation of renal histopathology is helpful in predicting early and late renal outcome. Chronicity and proteinuria were the best determinants of poor renal prognosis. Activity may regress under therapy, while chronicity may progress despite treatment. The amount of CYC seems to influence the occurrence of early relapses and renal survival.
Neumann
Irmgard
I
Department of Nephrology, Wilhelminenspital, Vienna, Austria. irmgard.neumann@nep.wil.magwien.gv.at
Kain
Renate
R
Regele
Heinz
H
Soleiman
Afschin
A
Kandutsch
Sandra
S
Meisl
Franz Thomas
FT
D000293:Adolescent; D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000276:immunology*; D001707:Biopsy, Needle; D003131:Combined Modality Therapy; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005500:Follow-Up Studies; D005921:Glomerulonephritis / Q000276:immunology / Q000473:pathology* / Q000628:therapy; D006801:Humans; D007150:Immunohistochemistry; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D006435:Renal Dialysis / Q000379:methods; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D016896:Treatment Outcome; D014657:Vasculitis / Q000276:immunology / Q000473:pathology* / Q000628:therapy
D000305:Adrenal Cortex Hormones; D019268:Antibodies, Antineutrophil Cytoplasmic