Classification Tree for the Diagnosis of Wegener's Granulomatosis

Wegener's Granulomatosis (WG) can be diagnosed using a classification tree approach.

top level	second level	third level	fourth level	diagnosis
granulomatous inflammation present on biopsy (or hemoptysis if no biopsy data)	nasal or oral inflammation present			WG
	nasal or oral inflammation absent	abnormal chest radiograph		WG
		normal chest radiograph		non-WG
granulomatous inflammation absent on biopsy (or no hemoptysis if no biopsy data)	nasal or oral inflammation present	abnormal chest radiograph		WG
		normal chest radiograph	abnormal urine sediment	WG
			normal urine sediment	non-WG
	nasal or oral inflammation absent			non-WG

where:

• The criteria are the same as for the traditional format.

• Hemoptysis present during the illness can be used if biopsy data is not available

Patient Subsets	Findings
WG patients	absence of granulomatous inflammation on biopsy; nasal or oral inflammation present; abnormal chest radiograph
	absence of granulomatous inflammation on biopsy; nasal or oral inflammation present; normal chest radiograph; abnormal urine sediment
	granulomatous inflammation on biopsy; nasal or oral inflammation present
	granulomatous inflammation on biopsy; absence of nasal or oral inflammation; abnormal chest radiograph
non-WG patients	absence of granulomatous inflammation; absence of nasal or oral inflammation
	absence of granulomatous inflammation; nasal or oral inflammation present; normal chest radiograph; normal urinary sediment
	granulomatous inflammation on biopsy; absence of nasal or oral inflammation; normal chest radiograph

Performance:

• The sensitivity is 87.1% and specificity is 93.6%

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