(A) Sensitivity and specificity values seen in the 827 patients with HSP versus the other forms of childhood vasculitides (c-PAN 150, c-WG 60, c-TA 87). (A) Sensitivity and specificity values seen in the 827 patients with HSP versus the other forms of childhood vasculitides (c-PAN 150, c-WG 60, c-TA 87). (B) Sensitivity and specificity values seen in the 150 patients with c-PAN versus the other forms of childhood vasculitides (HSP 827, c-WG 60, c-TA 87). c-PAN, childhood polyarteritis nodosa; c-TA, c-Takayasu arteritis; c-WG, Wegener granulomatosis; HSP, Henoch–Schönlein purpura. Seza Ozen et al. Ann Rheum Dis 2010;69:798-806 ©2010 by BMJ Publishing Group Ltd and European League Against Rheumatism