MPO and microscopic polyangiitis: The area under curve (AUC) was determined for PR3-ANCA employing 90 sera of patients with GPA as positive criterion at 0.896 (95% confidence interval [CI]: 0.864–0.923) and for MPO-ANCA using 28 patients with MPA as positive criterion at 0.934 (95% CI: 0.904–0.957); p<0.0001, respectively.