Men 45 years or older who received pneumococcal vaccine were not less likely to have a heart attack or stroke compared to men who did not receive the vaccine, according to a study in the May 5 issue of JAMA.
Hung Fu Tseng, Ph.D., of Kaiser Permanente Southern Califor¬nia, Pasadena, and colleagues conducted a study to examine the association between vaccination with pneumococcal vaccine and the risk of developing acute heart attack and stroke in men, taking into account known and potentially important confounders (factors that can influence a study, leading to unexpected outcomes that improperly skew the results).
The study included Kaiser Permanente Northern and Southern California health plans, with 84,170 participants ages 45 to 69 years from the California Men's Health Study, who were recruited between Janu¬ary 2002 and December 2003, and followed up until December 31, 2007. The cohort was similar to the population of health plan members and men who responded to a gen¬eral health survey in California on important demographic and clinical characteristics. Demographic and detailed lifestyle characteristics were collected from surveys. Vaccination records were obtained from the Kaiser Immunization Tracking System.
During follow-up, there were 1,211 first myocardial infarctions (MIs; heart attack) in vaccinated persons (rate of 10.7 per 1000 person-years) compared with 1,494 first MI events in unvaccinated individuals (6.07 per 1000 person-years). For stroke, there were 651 events in vaccinated persons (5.3 per 1000 person-years) compared with 483 events in unvaccinated persons (1.9 per 1000 person-years). After analysis of the data, the researchers found no evidence for an association between pneumococcal vaccination and reduced risk of acute MI or stroke. "In addition, association was not observed either in the current smokers, men with his¬tory of diabetes, men with history of hy¬pertension, or men of the low-risk group."
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Mohammad Madjid, M.D., M.S., and Daniel M. Musher, M.D., of the Texas Heart Institute, St. Luke's Episcopal Hospital, and Bay¬lor College of Medicine, Houston, comment on the findings of this study.
"The study by Tseng et al is another important reminder of the complexities involved in evaluating observational stud¬ies examining the relationship between vaccine adminis¬tration and clinical outcomes, and the need for more robust study designs. Until rigorous data from clinical trials are available to determine whether pneumonia vaccine can prevent MI, physicians should strictly adhere to available guidelines for optimizing vaccination rates in recom¬mended target groups, because these rates are still far from optimal."
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