Problems of classification of Henoch Schonlein purpura: an Indian perspective

A 2-year prospective study was carried out in which 71 patients with primary cutaneous vasculitis were classified using the American College of Rheumatology (ACR) classification and the Chapel Hill Consensus Conference (CHCC) recommendations for Henoch Schonlein purpura (HSP). The sensitivity of the ACR criteria was 64.8% and that of the CHCC definition 31%. When the ACR criteria were combined with results of direct immunofluorescence (DIF) the sensitivity was 78.9%. The concordance between the two systems was low as only 12 patients fulfilled criteria for both classifications. Although the ACR criteria were found to be more useful in the classification of HSP our data suggest that they need to be modified to include adults with disease. The age at onset of disease was higher than that in the west. Seventy per cent of patients identified by either classification were > 20 years of age. The prevalence of gut involvement, microhaematuria and proteinuria was < 25% in both groups. The sensitivity of histopathology on the other hand was 80.4% and was not influenced by the duration of the lesion. The DIF test was a useful adjunct to histopathology if it was done within 48 h as the yield of a positive test was significantly higher in this group as compared to the patients who had the test done later.