Among older men in an ethnically and socioeconomically diverse California population, those who received the pneumococcal vaccine did not have a lower risk of acute MI or stroke than did those who were unvaccinated, according to researchers.
Influenza vaccination has been shown to reduce the risk of MI, stroke, sudden cardiac death, cardiac hospitalization, and the need for revascularization, and similar results recently have been reported for vaccination against pneumococcus, said Hung Fu Tseng, Ph.D., of Kaiser Permanente Southern California, Pasadena, and his associates.
It is thought that respiratory infections, particularly influenza and pneumococcal pneumonia, can trigger an exaggerated inflammatory response that causes destabilization of atherosclerotic plaques, activation of the coagulation cascade, and vascular thrombosis.
To explore the possible protective effect of pneumococcal vaccine against MI and stroke, Dr. Tseng and his colleagues reviewed data collected as part of a cohort study of men's health, which involved 84,170 subjects enrolled in the Kaiser health plan who were aged 45–69 years at baseline in 2000 and who were followed through 2007.
There were 2,705 incident acute MIs and 1,134 incidents strokes.
The rate of MI was 10.7 per 1,000 person-years in men who received at least one pneumococcal vaccination, compared with 6.1 per 1,000 person-years in men who had not received any pneumococcal vaccinations. The rate of stroke was 5.3 per 1,000 person-years in vaccinated men and 1.9 per 1,000 person-year in unvaccinated men.
“With adjustment for the propensity score, we found no evidence for an association between pneumococcal vaccine and reduced risk of acute MI or stroke” in the general study population. Moreover, there also was no protective effect in important subgroups such as smokers, men with diabetes, men with hypertension, and men with low cardiovascular risk (JAMA 2010;303:1699–706).
These results contrast with the findings from a well publicized recent case-control study. Dr. Tseng's study was different in that it controlled for subjects' dietary habits, disease history, and lifestyle factors. His study also adjusted for the fact that older men who receive the pneumococcal vaccine are more likely to get vaccinated because they have chronic conditions that heighten their risk for MI and stroke, the researchers noted.
The California Cancer Research Program and Kaiser Permanente funded the study. Dr. Tseng and associates reported ties to Merck, maker of a pneumococcal vaccine, and GlaxoSmithKline.
In a study of older men that controlled for dietary habits, disease history, and lifestyle factors, pneumococcal vaccines did not show a protective effect against MI or stroke.
Source Pamela Moore/iStockphoto.com