1990 Criteria for the Classification of Giant Cell (Temporal) Arteritis - Tree Format

GCA subsets

7. Age ≥50 at disease onset and tenderness or decreased temporal artery pulsation

5. Age ≥50 at disease onset and artery biopsy showing mononuclear cell or granulomatous inflammation, with clinically
    normal temporal arteries

3. Age ≥50 at disease onset, claudication, normal temporal arteries and negative biopsy

Non-GCA

1. Vasculitis, with normal temporal arteries, no claudication, and negative biopsy

2. Vasculitis, age <50 at disease onset, claudication, normal temporal arteries, and biopsy without specified findings

4. Vasculitis, age <50 at disease onset, clinically normal temporal arteries, and biopsy with specified findings

6. Vasculitis, with abnormal temporal arteries, age <50 at disease onset

* The subset numbers also appear below the subset boxes in Figure 1. Missing data rules: If temporal artery findings are not available, substitute scalp tenderness; if biopsy findings are not available, substitute headache; if other findings are not available, the vasculitis cannot be classified. The classification tree yields a sensitivity of 95.3% and a specificity of 90.7%. See Table 4 for definitions of criteria.