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Chlamydia Pneumoniae a Risk Factor for Stroke: Presented at AAN

By Charlene Laino

HONOLULU, HI -- April 7, 2003 --- Chlamydia pneumoniae infection may be a modifiable risk factor for ischaemic stroke, say researchers who found that patients who have serologic evidence of infection with C. pneumoniae are more likely to suffer a stroke than those who have no evidence of infection.

Mitchell S. Elkind, MD, assistant professor of neurology at the Neurology Institute of Columbia University in New York City, United States, presented study results here on April 2^nd at the 55^th Annual Meeting of American Academy of Neurology.

Dr. Elkind said he undertook the study because C. pneumoniae infection has been associated with cardiovascular disease in multiple epidemiologic studies, but the data on its association with ischaemic stroke are limited.

The population-based case-control study enrolled 218 residents of northern Manhattan over age 54 years old, who had experienced their first ischaemic stroke. Three hundred and thirty seven controls were found through random-digit dialing, and matched to cases by age, sex and race-ethnicity.

The researchers measured titers of IgG, IgA, and IgM antibodies specific for C. pneumoniae using microimmunofluorescence, with titers >/=1:16 were prespecified as being positive, Dr. Elkind said.

Just over half (51%) of the 218 cases, whose mean age was 72, were women; 57.1% were Hispanic, 25.4% black, and 17.5% white, he reported. C. pneumoniae IgG titers were elevated in 64.5% of cases and 54.6% of controls, and IgA titers were elevated in 44.4% of cases and 35.3% of controls.

After adjusting for hypertension, diabetes, elevated cholesterol, atrial fibrillation and current smoking, patients with high IgG levels were 60% more likely to have had a stroke than those with normal levels, and individuals with elevated IgA titers were 50% more likely to have had a stroke, Dr. Elkind said.

The results were similar for men and women, the study found.

To confirm their findings, the researchers repeated the analysis using a higher cutoff for a positive IgG titer (>/=1:64), and found that 47.7% of cases and 39.6% of controls had elevated titers. Again, those with elevated levels were 70% more likely to have had an ischaemic stroke than those with normal levels, Dr. Elkind said.

Pointing out that the association between elevated C. pneumoniae titers and ischaemic stroke appears to be independent of traditional stroke risk factors, the researchers concluded that prospective studies are warranted.


[Study title: Antibodies to Chlamydia Pneumoniae Are Associated with Risk of Ischemic Stroke. Abstract: S33.003]

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