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Risk of Recurrent Stroke
Compared with data on risk factors
for an initial stroke, information on risk factors for recurrent
ischemic stroke is limited, and the reported rates of stroke
recurrence vary. This may be due to methodological differences
in analysis or differences in age, gender, or coexistent morbidities
among the cohorts studied.
The Lehigh Valley Recurrent Stroke Study examined
the frequency of a second stroke after an initial ischemic
stroke in terms of five widely recognized risk factors (hypertension,
myocardial infarction, cardiac arrhythmia, diabetes mellitus,
and transient ischemic attacks). 621 patients with an
acute ischemic stroke were followed prospectively first at
4 months after onset and then at approximately 6-month intervals
until death, recurrence of stroke, or the end of the study
(48 months). Multifactorial regression analysis was
conducted using the risk factor status at enrollment and adjusted
for age and sex.
Men comprised 52% of the cohort. The average
age at initial stroke onset was 70±11 years for women.
Multiple risk factors were present in 57% of these patients:
hypertension in 59%, cardiac arrhythmia in 47% (of which 16%
had atrial fibrillation), diabetes mellitus in 30%, myocardial
infarction in 25%, and TIA in 18%.
By the end of the study, 12% of the patients
had a second stroke, 21% died, 4% moved out of the study areas,
and 10% refused further follow-up.
Each selected risk factor was tested individually
for its influence on the likelihood of stroke recurrence.
Only history of hypertension and atria fibrillation by ECG
were associated with increased risk of second stroke independently
and significantly (p=0.01 and p=0.04, respectively).
However, when the treatment of diabetes mellitus was considered,
diabetic patients treated with insulin had higher cumulative
stroke recurrence rates than diabetic patients not requiring
insulin or than non-diabetic patients.
Ischemic stroke patients with a history of hypertension
at the time of initial stroke had a 1.9-fold (95% CI=1.18
to 3.24) higher risk of subsequent stroke compared with those
who were the same age and gender but had no history of hypertension.
Patients with atrial fibrillation at baseline had 1.8-fold
(95% CI=1.04 to 3.06) higher risk compared with those without
atrial fibrillation. Patients with both hypertension
and atrial fibrillation at baseline had 3.5-fold higher risk
of recurrent stroke compared with patients of the same age
and gender without either of these risk factors.
The investigators concluded that: (1) This type
of study could be used to examine additional risk factors
(e.g., lipid profile, insulin concentration, smoking) for
their effect on risk of stroke recurrence, and (2) control
of risk factors need to be evaluated for an effect on reducing
risk. With regard to the latter, they noted that unpublished
data based on the present cohort suggested that control of
hypertension reduced risk of stroke recurrence to a level
close to that of non-hypertensive patients.
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Stroke Education
