Chlamydia pneumoniae antibodies and high lipoprotein(a) levels do not predict ischemic cerebral infarctions. Results from a nested case-control study in Northern Sweden.

BACKGROUND AND PURPOSE An association between high lipoprotein(a) [Lp(a)] levels and positive Chlamydia pneumoniae IgG titers in coronary artery disease has been described. The possibility of predicting ischemic stroke by measurements of plasma Lp(a) and C pneumoniae antibodies was investigated. METHODS This incident case-control study included 101 case subjects (cases) who had suffered ischemic cerebral infarctions and 201 matched control subjects (controls). The study population was nested within the Västerbotten Intervention Program or the WHO MONICA project. Plasma samples were measured for C pneumoniae-specific IgG and IgA antibodies and Lp(a). RESULTS A significantly higher mean Lp(a) level was found in female cases than in female controls. However, plasma Lp(a) was unable to predict ischemic cerebral infarctions in either women or men. The proportion of individuals with positive C pneumoniae-specific IgG or IgA titers did not differ between cases and controls. Antibody titers were unable to predict a future stroke. The proportion of individuals with a positive C pneumoniae IgG titer in combination with a high Lp(a) level did not differ significantly between cases and controls. CONCLUSIONS These data suggest that there is no association between baseline plasma Lp(a) levels, presence of C pneumoniae antibodies, and future ischemic cerebral infarctions. Furthermore, no evidence of an interactive effect between high Lp(a) levels and C pneumoniae IgG titers was found. However, selection bias and a recent C pneumoniae epidemic may have influenced the results.