Pitfalls in recommending evidence-based guidelines for a protean disease like Henoch–Schönlein purpura nephritis

Abstract

The long-term prognosis of Henoch–Schonlein purpura nephritis (HSPN) depends on the severity of initial clinical symptoms and histological features [1, 2]. The risk of evolution into a chronic kidney disease (CKD) may be as high as 50, 40 and 15 % for the combination of onset with nephrotic and nephritic syndrome, nephrotic syndrome, nephritic syndrome and/or heavy non-nephrotic proteinuria, respectively [1]. The International Study of Kidney Disease in Children (ISKDC) classified the risk of progression on the basis of the histology severity mainly according to the extent of crescent formations. Combining three studies with a follow-up of about 6 years [3–5], Haas [2] demonstrated that 25 % of children biopsied for HSPN had severe outcomes (persistently active renal disease and/or worsened stages of CKD, including endstage renal failure), in correlation with the ISKDC grades of renal pathology damage. These data indicate that children with HSPN have to be carefully followed, since some cases can have a catastrophic evolution. However, the therapeutic choice can be challenging because—apart from mild renal clinical symptoms and histological lesions that almost always are associated with good long-term outcome, and the association of nephrotic and nephritic syndrome with high histological grade [1–6] that most frequently leads to CKD—the long-term prognosis cannot predicted with certainty at disease onset. More importantly, there is a paucity of evidence-based (EB) data to guide treatment decisions for HSPN. Doctors are therefore confronted with the dilemma of undertreatment and increased risk of CKD or over-treatment and the risk of unnecessary side effects. Recently, the Kidney Disease Improving Global Outcome (KDIGO) initiative published guidelines on the treatment of HSPN [7]. In view of the lack of EB data for HSPN treatment and similarities between HSPN and primary immunoglobulin A nephropathy (IgAN), the KDIGO guidelines resorted to data regarding the treatment of the two diseases in similar clinical conditions. The aims of the present paper are: