Risk factors of renal involvement and significant proteinuria in patients with Henoch-Schönlein purpura (HSP) were retrospectively evaluated by univariate and multivariate analyses. The analysis was performed in 134 patients with HSP. Renal involvement was found in 65 patients (49%) and 97% of the renal involvement was found within 3 months of disease onset. Moderate or severe proteinuria was recognised in 25 patients. A univariate analysis revealed that an age of more than 4 years at the onset, severe abdominal pain with gastrointestinal bleeding, persistent purpura over a month, coagulation factor XIII activity < 80%, and treatment with factor XIII concentrate were associated with developing renal involvement. A multivariate analysis showed that severe abdominal symptoms, an age of more than 4 years, and persistent purpura increased the risk of renal involvement. Risk factors of moderate or severe proteinuria were also examined. The risk factors in a univariate analysis were severe abdominal symptoms, persistent purpura, decreased factor XIII activity, treatment with steroids, and treatment with factor XIII concentrate. Of those, persistent purpura, treatment with factor XIII concentrate, and factor XIII activity < 80% were associated with significant proteinuria in a multivariate analysis. Among the patients with severe abdominal symptoms, factor XIII activity was significantly decreased in patients with significant proteinuria compared to other patients without significant proteinuria.
Conclusion: Long-term prognosis of Henoch-Schönlein purpura is dependent on the severity of renal involvement. In those patients who have the risk factors of renal involvement, especially significant proteinuria, close attention should be paid to a urinalysis for at least 3 months from the onset of the disease.