Effect of untreated hypertension on hemorrhagic stroke.
OBJECTIVE
Stroke is the third leading cause of death and the leading cause of disability in the United States. Intracerebral hemorrhage and subarachnoid hemorrhage represent approximately 20% of all stroke cases and have a mortality rate of 40% to 50%. Hypertension is an important risk factor for these subtypes of stroke. We sought to determine whether untreated hypertension carries a different risk from treated hypertension for hemorrhagic stroke.


METHODS
Cases of hemorrhagic stroke in the greater Cincinnati region were identified by screening all area hospital emergency rooms, radiology reports, and International Classification of Diseases 9 codes. Medical records were reviewed for risk factors and medication use. Cases of hemorrhagic stroke were approached for enrollment into the genetic sampling and interview arm. If subjects agreed, the case was matched by age, race, and gender to population-based controls.


RESULTS
Between May 1997 and December 2002, we recruited 549 cases of hemorrhagic stroke, of which 322 were intracerebral hemorrhage and 227 were subarachnoid hemorrhage. Untreated hypertension was found to be a significant risk factor for hemorrhagic stroke (odds ratio [OR]=3.5 [2.3 to 5.2]; P<0.0001) as was treated hypertension (OR=1.4 [1.0 to 1.9]; P=0.03). Insurance status of "self-pay" or Medicaid was a significant risk factor for untreated hypertension (OR=2.7 [1.6 to 4.4]). We estimate that 17% to 28% of hemorrhagic strokes among hypertensive patients would have been prevented if they had been on hypertension treatment.


CONCLUSIONS
Untreated hypertension is highly prevalent and an important risk factor for hemorrhagic stroke. We estimate that among hypertensive subjects, approximately one fourth of hemorrhagic strokes would be prevented if all hypertensive subjects received treatment.
Woo
Daniel
D
University of Cincinnati College of Medicine, 231 Albert Sabin Way, ML 0525, Cincinnati, OH 45267-0525, USA. Daniel.woo@uc.edu
Haverbusch
Mary
M
Sekar
Padmini
P
Kissela
Brett
B
Khoury
Jane
J
Schneider
Alexander
A
Kleindorfer
Dawn
D
Szaflarski
Jerzy
J
Pancioli
Arthur
A
Jauch
Edward
E
Moomaw
Charles
C
Sauerbeck
Laura
L
Gebel
James
J
Broderick
Joseph
J
D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000188:drug therapy; D020299:Intracranial Hemorrhage, Hypertensive / Q000453:epidemiology*; D008297:Male; D012307:Risk Factors; D020521:Stroke / Q000453:epidemiology / Q000209:etiology; D013345:Subarachnoid Hemorrhage / Q000453:epidemiology