Outcome in glomerulonephritis due to systemic small vessel vasculitis: effect of functional status and non-vasculitic co-morbidity.

BACKGROUND: Previous studies in systemic vasculitis have defined a number of disease-specific factors including histological parameters and clinical vasculitis activity scores as outcome predictors. This study evaluates the previously neglected role of non-vasculitic factors in determining prognosis in this condition.
METHODS: We performed a retrospective study of all patients with a diagnosis of small vessel vasculitis (SVV) presenting with renal impairment to our service over a 12-year period.
RESULTS: Eighty-six patients were studied (median age 63.5 years, 64% male). Mean plasma creatinine at presentation was 533 micro M (6.3 mg/dl). Forty-seven patients (55%) required immediate dialysis, 21 (45%) recovered renal function on treatment. The presence of crescent fibrosis (P < 0.05) and interstitial fibrosis (P < 0.01) were significantly associated with a failure to recover renal function. There was a trend towards an increased relapse rate in those with a persistently positive ANCA result or a rising titre. Twelve month patient survival was 85.5% and 5-year survival was 63%. Factors independently associated with mortality were Karnofsky performance score at diagnosis (P < 0.00001), intensity of immunosuppressive treatment (P = 0.0007) and vasculitis classification (P = 0.009). Non-vasculitic co-morbidity was not independently associated with mortality. Patients who were, or became after treatment, dialysis-independent had a significant survival advantage (5-year survival 83 vs 42%, P = 0.001).
CONCLUSIONS: Non-vasculitic factors, particularly functional status as indicated by the Karnofsky performance score, play a major role in determining prognosis in SVV with renal involvement and should be an integral component of the decision making process when planning therapy, and in comparing outcomes between centres.