Table 1:

Diagnosis codes used to define the study population

Variables used to define the study population	ICD-9 codes used
Codes for acute hypertension
Primary malignant hypertension	401.0
Secondary malignant hypertension	405.01 and 405.09
Malignant hypertensive heart or kidney disease	402.00, 402.01, 403.00, 403.01, 404.00, 404.01, 404.02, 404.03
Codes for end-organ damage
Retinal hemorrhage	362.81
Papilledema with increase intracranial pressure	377.01
Acute on unspecified (not chronic) heart failure	428.0, 428.1, 428.20, 428.21, 428.23, 428.30, 428.31, 428.33, 428.40, 428.41, 428.43, 428.9
Acute myocardial infarction	410.x, 410.xx
Ruptured aortic aneurysm or aortic dissection	414.12, 443.21, 443.22, 443.23, 443.24, 443.29, 441.x
Subarachnoid hemorrhage	430.x
Intracerebral hemorrhage	431.x
Hypertensive encephalopathy	437.2
Non-traumatic extradural hemorrhage	432.x
Cerebral thrombosis	434.x
Transient cerebral ischemia	435.x
Other cerebrovascular disease	436.x