Infection and risk of ischemic stroke: differences among stroke subtypes.
OBJECTIVE
Although prior studies have demonstrated that 25% to 35% of stroke patients have had a recent infection, the role of infection as a risk factor remains unclear. Our aim was to characterize the effect of infectious/inflammatory syndromes on stroke risk.


METHODS
Case-control and crossover analyses of 233 cases and 363 controls aged 21 to 89 years were performed. Cases were patients hospitalized with a first ischemic stroke at a Los Angeles, California, medical center. Controls were outpatients in the hypertension, diabetes, and general medical clinics. All subjects were administered a neurological examination, an infection/inflammation (I/I) examination, and an interview to elicit recent I/I history at baseline (within several days of stroke onset) and again approximately 2 months later. Three physicians classified subjects by the presence or absence of I/I within 1 month of the index dates, based on findings of the I/I examination, the interview report, and laboratory results.


RESULTS
Infections, either total or specific, were not found more frequently in cases than controls. However, patients with a recent respiratory tract infection suffered more often from large-vessel atherothromboembolic or cardioembolic stroke than did patients without infection (48% vs 24%, P=0.07). The age- and sex-adjusted relative risk estimate for these subtypes was 1.75 (95% CI, 0.86 to 3.55). The risk was notably high for those without stroke risk factors: 4.15 (95% CI, 1.22 to 14.1) for normotensives, 2.71 (95% CI, 1.04 to 7.06) for nondiabetics, and 1.74 (95% CI, 0.74 to 4.07) for nonsmokers. Patients with a recent respiratory infection also had a more severe neurological deficit on admission than those without infection (P=0.05).


CONCLUSIONS
Our results suggest that respiratory tract infection may act as a trigger and increase the risk of large-vessel and/or cardioembolic ischemic stroke, especially in those without vascular risk factors.
Paganini-Hill
A
A
Department of Preventive Medicine of the Keck School of Medicine of the University of Southern California, Los Angeles, USA. annliahi@usc.edu
Lozano
E
E
Fischberg
G
G
Perez Barreto
M
M
Rajamani
K
K
Ameriso
S F
SF
Heseltine
P N R
PN
Fisher
M
M
D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D002545:Brain Ischemia / Q000453:epidemiology; D016022:Case-Control Studies; D015984:Causality; D015897:Comorbidity; D018592:Cross-Over Studies; D003710:Demography; D005260:Female; D006801:Humans; D007239:Infections / Q000453:epidemiology*; D020766:Intracranial Embolism / Q000453:epidemiology; D020767:Intracranial Thrombosis / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012306:Risk; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D017678:Sex Distribution; D020521:Stroke / Q000145:classification* / Q000453:epidemiology*