Eric Thervet MD. PhD.

Service de Néphrologie et Transplantation Rénale.
Hôpital Saint-Louis. Paris, France
eric.thervet@sls.ap-hop-paris.fr

Henoch-Schönlein purpura (HSP) is a leucocytoclastic vasculitis involving small vessels with the deposition of immune complexes containing immunoglobulin A (IgA). It is characterized by the association of skin, joint and gastrointestinal manifestations which may occur in successive episodes¹. In addition to these manifestations, renal involvement is common, and the long-term prognosis depends on its severity

HSP primarily affects children and its incidence is around 15 cases/100,000 children/year². It is less common in adults, approximatively 0.8 cases/100,000 adults/year. Although HSP has been extensively studied in children, much less is known about its natural history in adults.

Even though the prognosis is considered to be good, some severe forms can exist.

During the initial presentation, gastrointestinal, cardiac, pulmonary, neurological and ocular manifestations can be severe. However, the most important visceral manifestation is renal because of its short and long-term implications.

The incidence of adult visceral involvement is variable. Severe gastro-intestinal bleeding has been reported in up to 40 % responsible for bloody diarrhea. Other complications such as acute pancreatitis, enteropathy and colonic perforations can be observed. A cardiac involvement can be observed in 3,8 % of patients with pericarditis or myocardial infarct. Clinical pulmonary involvement is present in only 2 % of patients. However, the involvement is more frequent when looked systematically using CT scan or functional pulmonary test. Neurological involvement, in 1 % of patients, is responsible for cephalagia secondary to cerebral vasculitis or rare cerebral hemorraghe or infarct.

Renal involvement varies from 45 to 85% of cases, depending on the data for patients and of renal involvement definition³. Among the cases of glomerulonephritis, HSP is only responsible for 0.6 to 2% of adults nephropathies^{3, 4, 5}. The risk of progression to renal insufficiency, 15%^{6, 7, 8} in children, seems to be higher when a long follow-up is possible⁹ or in adults, in more than 30% ¹⁰.

We analyzed retrospectively 250 adults suffering from HSP, with biopsy proven renal involvement. Evidence of renal involvement was detected within a median period of 2 months after onset of the first clinical symptoms. Hypertension was frequent. Hematuria was present in more than 90% of patients such as proteinuria with nephritic syndrom in 30 % of patients. The most frequent lesion in renal biopsies was proliferative endocapillary glomerulonephritis with possible extracapillary glomerulonephritis was only present in 8% (Figure 1).

In this study, mortality rate was 26%. The most frequent cause of death was neoplasia (27% of deaths) not related to immunosuppressive treatment. The second cause of death was infection (16%), two third being attributable to immunosuppressive treatment. Death was secondary to HSP evolution in 11%, due, in particular, to severe digestive involvement. Regarding renal survival, 11% of patients developed end stage renal failure, 13% had severe renal failure, and 14%, moderate renal insufficiency (Figure 2). It is clear from our experience and others that long-term prognosis of HS purpura may be more severe than once described.

However, there is no consensus or randomized study existing to give guidelines regarding treatment.

Prognostic factors for severe renal impairment are the following. Clinical presentation, including purpura, arthritis and abdominal involvement, was not associated with a significant difference in renal function at the end of the follow up. Age over 50 years, the presence of renal failure at onset, proteinuria >1g/l and the presence of macroscopic hematuria, were strong predictors of severe renal failure. On renal biopsy, the glomerular classification, the number of global sclerotic glomeruli and the degree of interstitial fibrosis were also predictive of the renal outcome.

As to the efficacy of specific treatments, the results of pediatric therapeutic studies^11-13, even though none was prospective and randomized against placebo, were mostly positive. In adults, it is difficult to draw any conclusions from our study since their administration was frequently associated with both clinical and histologic risk factors for renal failure (Figure 3). On univariate analysis, steroids even seem to worsen the course of renal evolution. As in most previous retrospective studies of HSP nephropathy, the limitation of the present investigation was that the distribution of established renal risk factors was different in treated or not treated patients.

We recently initiated a large multicentric, randomised, prospective study to evaluate the efficacy and safety of steroid treatment, either alone or combined with cyclophosphamide in severe forms of Henoch-Schönlein purpura in adults^{14, 15}. This study will include patients with severe visceral involvement of HS purpura in adults including all the clinical forms described in the beginning of this manuscript. The primary end-point will be the control of the clinical acute disorder evaluated by the Birmingham Vasculitis Activity Score. The secondary end-points will be the presence of chronic damage including chronic renal failure. The results are awaited for the end of 2007.