Abnormal urinalysis on day 7 in patients with IgA vasculitis (Henoch–Schönlein purpura)

Rare progression to renal failure imposes a burden on children with IgA vasculitis (Henoch-Schönlein purpura, HSP). An abnormal urinalysis on day 7 (7d-UA) may be a surrogate marker for persistent nephritis, but this has not been established. We retrospectively analyzed the risk factors for persistent nephritis in a cohort of 138 children. Of 35 children with abnormal 7d-UA, 24 (69%) had an abnormal urinalysis 6 months after the diagnosis of HSP, which was significantly more than 6 of 103 children (6%) with normal 7d-UA (P < 0.0001). The negative predictive values for normal urinalysis and negative proteinuria 6 months after diagnosis were 0.94 (95% confidence interval [CI], 0.90-0.97) and 0.98 (95% CI, 0.95-0.99), respectively. When children with abnormal urinalysis 6 months after diagnosis were compared with those without, the following factors were significantly associated: age at diagnosis, abnormal urinalysis at diagnosis, abnormal 7d-UA, complement C3, steroid treatment, and presence of abdominal pain. However, multivariate analysis revealed that abnormal 7d-UA was the only significant risk factor for abnormal urinalysis 6 months after diagnosis (odds ratio 54.3, 95% CI 15.3-275, P = 1.89 × 10-6). Abnormal 7d-UA may be an independent risk factor for persistent nephritis, but this should be confirmed in a prospective study.