Pneumococcal vaccination and risk of myocardial infarction.
BACKGROUND
Based on promising results from laboratory studies, we hypothesized that pneumococcal vaccination would protect patients from myocardial infarction.


METHODS
We conducted a hospital-based case-control study that included patients considered to be at risk of myocardial infarction. We used health databases to obtain hospital diagnoses and vaccination status. We compared patients who had been admitted for treatment of myocardial infarction with patients admitted to a surgical department in the same hospital for a reason other than myocardial infarction between 1997 and 2003.


RESULTS
We found a total of 43 209 patients who were at risk; of these, we matched 999 cases and 3996 controls according to age, sex and year of hospital admission. Cases were less likely than controls to have been vaccinated (adjusted odds ratio [OR] 0.53, 95% confidence interval [CI] 0.40-0.70). This putative protective role of the vaccine was not observed for patients who had received the vaccine up to 1 year before myocardial infarction (adjusted OR 0.85, 95% CI 0.54-1.33). In contrast, if vaccination had occurred 2 years or more before the hospital admission, the association was stronger (adjusted OR 0.33, 95% CI 0.20-0.46).


CONCLUSIONS
Pneumococcal vaccination was associated with a decrease of more than 50% in the rate myocardial infarction 2 years after exposure. If confirmed, this association should generate interest in exploring the putative mechanisms and may offer another reason to promote pneumococcal vaccination.
Department of Medicine, Université de Sherbrooke, Sherbrooke, Que.
François
F
Lamontagne
Marie-Pierre
MP
Garant
Jean-Christophe
JC
Carvalho
Luc
L
Lanthier
Marek
M
Smieja
Danielle
D
Pilon
D017677:Age Distribution; D000368:Aged; D016022:Case-Control Studies; D016001:Confidence Intervals; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology* / Q000517:prevention & control; D016017:Odds Ratio; D022242:Pneumococcal Vaccines / Q000008:administration & dosage*; D011018:Pneumonia, Pneumococcal / Q000453:epidemiology / Q000517:prevention & control*; D011336:Probability; D012016:Reference Values; D012042:Registries; D018570:Risk Assessment; D017678:Sex Distribution; D015996:Survival Rate; D014611:Vaccination / Q000379:methods*
D022242:Pneumococcal Vaccines