Table 3: Relationship between the results of ANCA testing and clinical diagnoses.

Diseases p-ANCA c-ANCA x-ANCA IIF (−)/ELISA (+) Anti-MPO (+) Anti-PR3 (+) Total (N) MPA N 45 4 6 6 46 10 61 % 73.8 6.6 9.8 9.8 75.4 16.4 WG N 6 34 1 5 4 40 46 % 13.0 73.9 2.2 10.9 8.7 87 CSS N 4 0 2 0 6 0 6 % 66.7 0.0 33.3 0.0 100 0.0 CTD N 97 2 31 2 9 1 132 % 73.5 1.5 23.5 1.5 6.8 0.7 GD N 67 10 40 0 1 8 117 % 57.3 8.5 34.2 0.0 17.9 7.7 Other vasculitides N 27 1 11 0 7 3 39 % 69.2 2.6 28.2 0.0 5.6 0.0 Infections N 23 1 12 0 2 0 36 % 63.9 2.8 33.3 0.0 5.6 0.0 ND N 23 1 9 0 0 0 33 % 69.7 3.0 27.3 0.0 0.0 0.0 Malignancies N 21 1 9 0 1 0 31 % 67.7 3.3 29.0 0.0 3.3 0.0 RD N 18 0 4 0 2 0 22 % 81.8 0.0 18.2 0.0 9.0 0.0 Medication N 10 0 5 0 0 0 15 % 66.7 0.0 33.3 0.0 0.0 0.0 Miscellaneous disorders N 5 2 6 1 0 1 14 % 35.7 14.3 42.9 7.1 0.0 7.1 Undefined diagnosis N 63 4 39 3 2 3 109 % 57.8 3.7 35.8 2.7 1.8 2.7

MPA: microscopic polyangiitis, WG: Wegener’s granulomatosis, CSS: Churg-Strauss syndrome, CTD: connective tissue diseases, GD: gastrointestinal diseases, ND: neurological diseases, RD: renal diseases.