The relation between histopathological classification and renal outcome, ANCA subtype and treatment regimens in ANCA-associated vasculitis.

OBJECTIVES: ANCA-associated vasculitis (AAV) is associated with an increased risk of death and end stage renal disease (ESRD). The aim of this study was to examine the correlation between a histopathological classification and renal outcome and to describe the interaction with ANCA subtype and initial treatment. METHODS: Eighty-seven patients with AAV from 1999-2010 from two centres in Denmark were included in the study and had a 3 year follow-up. Data was collected retrospectively. The renal biopsies were reclassi ed into one of the following groups: crescentic, sclerotic, focal and mixed. RESULTS: Histopathologic groups were not associated with eGFR at three years. Age and baseline eGFR were independent prognostic for eGFR at three years. More patients in the crescentic group than in the mixed and focal groups developed ESRD (33%, 13% and 5% respectively). Patients reaching ESRD had few- er non-affected glomeruli (14 % vs. 34%, p=0.0014) and lower eGFR at baseline (7 vs. 21.7 ml/min/m(2), p<0.0001). At baseline MPO-ANCA positive patients were older, had more sclerotic glomeruli and had a lower eGFR after three years compared to PR3-ANCA positive patients. PR3-ANCA positive patients receiving plasma exchange (PE) improved eGFR more from baseline to three years than those not receiving PE (36 vs. 20 ml/min/m2, p=0.01). CONCLUSIONS: In our cohort most pa- tients in the crescentic group and fewer in the focal group reached ESRD. Age and baseline eGFR are prognostic of renal function after 3 years, as also in the PR3-ANCA positive subgroup initial treatment with PE.