Table 2 .

Algorithms to ascertain atherosclerotic vascular disease cases and controls.

	ICD-9-CM codes to ascertain cases	ICD-9-CM codes to rule out controls
Carotid artery stenosis	433.1, 433.10, 433.11 – Occlusion and stenosis of carotid artery	433.xx – occlusion and stenosis of precerebral arteries
Abdominal aortic aneurysm	441.3-4, 441.6-7 – abdominal and thoracoabdominal aneurysm	441.xx – aortic aneurysm and dissection
Peripheral arterial disease	440.21–24 – atherosclerotic limb with claudication, rest pain, ulcer or gangrene	440.20–24, 440.0, 440.4, 443.9 – atherosclerotic extremity, peripheral vascular disease
Vascular procedures
Carotid stenting or endarterectomy	ICD-9-CM codes: 38.12 and 00.62; CPT-4: 35,301 and 0075 T
Abdominal aortic aneurysm repair	Open vascular repair: ICD-9-CM codes: 38.44, 39.52, 38.34, 38.64, 38.4, 38.6; CPT-4 codes: 33,877; Endovascular repair: CPT-4 codes: 34,800-05:
Lower extremity revascularization or surgery	Open vascular bypass: ICD-9-CM codes: 38.08, 38.18, 38.48, 38.48, 39.25; Angioplasty with or without stenting: ICD-9-CM codes: 39.50, 39.90; CPT-4 codes: 73,725, 75,635, 75,716; Major amputation: ICD-9-CM codes: 84.13–84.17

CPT-4: current procedural terminology codes version 4; ICD-9-CM: international classification disease codes version 9-CM.