Interest to Perform a Renal Biopsy Early in the Course of the Henoch-Schoenlein Nephritis

Henoch-Schönlein (HS) purpura is a common cause of renal glomerular injury in children. This condition is responsible for 10-15% of glomerulonephritis in children. The outcome is generally favorable, but up to 5% of patients develop kidney failure. The outcome of patients with kidney biopsy is less favorable with 7-50% of them progressing to chronic renal failure.

Prevalence of HS is difficult to determine from literature. Annual incidence is estimated at 6.1 / 100,000 children in the Netherlands and up to 20.4 / 100 000 children in the United Kingdom. The proportion of children with HS who develop renal disease is difficult to determine because the numbers reported in the literature are variable and depend greatly on the type of the reporting center, whether or not specialized in pediatric nephrology. Thus the proportion of renal disease varies from 20% to 100% of children with a HS.

The treatment of HS nephropathy (HSN) usually depends on the severity of histological lesions but histological classification is discussed and there is currently no consensus. Randomized studies are scarce and often do not allow to draw clear conclusions. A meta-analysis suggested a positive effect of corticosteroids on renal prognosis of severe forms but in this study the definition of renal disease was very heterogeneous. The only classification of the HSN recognized is from the International Study Group of Kidney Disease in Childhood (ISKDC) which is the following: grade I: minimal glomerula abnormalities, grade II: pure proliferation, grade III: crescents/ segmental lesions <50%,grade IV: crescents/ segmental lesions 50 to 75%, grade V: crescents/ segmental lesions > 75%, grade VI: pseudomesangiocapillary. However, this classification is questioned because it ignores other significant histological lesions such as interstitial fibrosis, tubular lesions, glomerular and interstitial inflammation, the appearance of crescents (segmental or totally encompassing the glomerulus, fibrous or cellular), segmental sclerosis, fibrosis and arteriolar appearance in immunofluorescence.

There is currently no consensus on the criteria indicating the initiation of corticosteroid therapy whether oral or intra venous bolus. Some patients with severe clinical and / or histological initial presentation can evolve to remission spontaneously while others who have more moderate initial symptoms will evolve later to kidney failure. The management is therefore heterogeneous. In France, some centers perform a kidney biopsy almost always before starting treatment (or in the days following the start of treatment), while in other centers's treatment decision is based on the biology resulting from the glomerular disease, kidney biopsy being performed possibly in a second time in case of failure of the initial treatment.

Principal objective of the study: assessment of the interest for the long term outcome of performing early a kidney biopsy (before the establishment of treatment or within 15 days after the start of treatment) in children with HSN compare to kidney biopsy performed later (depending on the response to initial therapy) or not performed.

Secondary objective: assessment of the impact of early kidney biopsy (before the establishment of treatment or within of 15 days after the start of treatment) on the initial treatment HSN : does it modify or not the treatment started right before it (decided on clinical and biological criteria).