ACR Criteria for the Classification of Hypersensitivity Vasculitis

Three of the following five criteria were required to meet American College of Rheumatology (ACR) classification criteria for hypersensitivity vasculitis:

1. Age at disease onset older than 16 years.
2. Medication at disease onset as a precipitating factor.
3. Palpable purpura.
4. Maculopapular rash.
5. Biopsy specimen showing granulocytes around an arteriole and venule.

These criteria have a reported sensitivity of 71% and a reported specificity of 83.9% for the classification of hypersensitivity vasculitis compared with other vasculitides.