HSN in adults is a serious relapsing disease, causing renal failure as frequently as in small-vessel ANCA-positive vasculitides. Prognosis and risks differed in this series from those in other countries, including a higher risk of ESRF than in previous series. Distinct groups developed either ESRF, or remitted. The absence of clear benefit suggests that corticosteroids should be reserved for patients with serious disease, and that cytotoxics may not be merited for those at high risk of renal failure.

Similarities between SVD PACNS and microscopic polyarteritis suggest the former may represent a limited form of the latter. MVD PACNS has a distinctly more benign relapse pattern than its multisystem counterpart polyarteritis nodosa. Acute-phase serology was useful in designating inflammatory processes at presentation of patients presenting with encephalopathy caused by SVD only, but were unhelpful in defining relapses in this form of PACNS, the definition of which in all cases rested on clinical assessment and MR scanning. Direct cerebral angiography was not diagnostic in any case of SVD PACNS; positive brain biopsy is diagnostically unequivocal, but the total clinical syndrome with imaging may establish a diagnosis with highest probability. In MVD PACNS, angiography with MR scan proved diagnostic. We suggest an algorithm for a rational, minimally invasive approach to investigation. In PACNS, SVD and MVD are important variants, and decisions about therapy should incorporate these distinctions.

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ABSTRACT. In a single-center, multiple-referral source study, 38 patients with progressive IgA nephropathy and controlled hypertension were randomized to treatment with prednisolone and cytotoxic agents, to therapy with low-dose cyclophosphamide then azathioprine, and to control groups. The follow-up period lasted 2 to 6 yr. Renal survival, as assessed by Kaplan-Meier analysis annually to 5 yr, showed significant preservation of function from 3 yr in the treatment group and 82, 82, 72, and 72% for 2, 3, 4, and 5 yr, respectively, compared with 68, 47, 26, and 6% in controls. Rate of loss of renal function, evaluated objectively by least-squares analyses of reciprocal serum creatinine, was reduced—and in one-third of the patients, arrested—during immunosuppressive treatment. Proteinuria, present in all patients at the time of entry into the trial, was reduced by treatment from 12 mo, compared with pretreatment levels or controls; erythrocyturia was reduced from 6 mo. Histologic activity and chronicity indexes were determined in renal biopsies performed at trial entry. Multivariate analysis demonstrated that mesangial cell proliferation and matrix scores were highest in those patients with more rapidly progressive disease. No morphologic variable or residual renal function predicted response to immunosuppressive therapy at entry. Mean arterial pressures did not differ significantly between treatment and control groups. There was thus no explanation other than treatment for the improved outcome in patients who received immunosuppressive therapy. Morbidity attributable to treatment or to renal failure occurred in both groups; an audit showed that benefits of therapy outweighed expected or minor side effects of drugs in this population at risk of end-stage renal failure. Patients selected for moderately progressive IgA nephropathy benefit from treatment with prednisolone and cytotoxic agents; results are consistent with modulation of systemic immune response or nephritic injury, thus explaining improved outcome, and indicate that this therapy has an acceptably low risk of side effects.

We have measured complement activation markers, C3dg and C5b-9 in plasma and urine from patients with idiopathic membranous nephropathy and IgA nephropathy. There was no significant difference in levels of plasma C5b-9 between the patient groups. However, high plasma concentrations of C3dg were associated significantly with IgA nephropathy with 45% of patients having levels over 25 U/ml (P less than 0.001). High concentrations of urinary C3dg and C5b-9 were associated significantly with membranous nephropathy (43% and 43% of the patient group, respectively) compared to patients with IgA nephropathy (10% and 0%, respectively, P less than 0.001). In a retrospective analysis of 31 patients with membranous nephropathy, 66% of patients with high initial urinary C5b-9 showed an unstable clinical course compared to 18% of patients with initially absent or low C5b-9 (P less than 0.001). We suggest that high urinary C5b-9 identifies those patients with a membranous lesion which retains an active immunological component contributing to the pathology of progressive glomerular damage.