Table 1.

Classification criteria for IgA vasculitis ^¶.

ACR Classification Criteria * (Mills et al., 1990) Ref. [38]	EULAR/PRINTO/PRES Classification Criteria * (Ozen et al., 2010) Ref. [39]
Two or more of the following: - age ≤ 20 years 1 - palpable purpura (not related to thrombocytopenia) 2 - acute abdominal pain: generally diffuse and worsens with Meals 3 - skin biopsy showing granulocytes inside small arteriolar or venular walls Sensitivity 87.1%; specificity 87.7%	MANDATORY: Purpura or petechiae with lower limb predominance 2 AND One or more of the following 4 criteria: - abdominal pain (diffuse with acute onset) 3 - arthritis or arthralgia (of acute onset) 4 - kidney involvement (proteinuria and/or hematuria) 5 - leucocytoclastic vasculitis with predominant IgA deposits or proliferative GMN with predominant IgA deposits Sensitivity 100%; specificity 87%

¹ Onset of the first symptoms at the age of 20 or less. ² Usually located on the buttocks, legs, or feet, but may also appear in other areas. ³ Often crampy in nature and may be associated with gastrointestinal manifestations such as nausea or vomiting. ⁴ Joint pain (arthralgia) or swelling (arthritis), commonly affecting the knees and ankles. ⁵ May include hematuria, proteinuria, or renal failure, as evidenced by laboratory tests. * The criteria were used primarily for children, but may also apply to adults. ^¶ This table has been modified from Hočevar et al. ref. [40]. GMN: glomerulonephritis.