Chlamydia pneumoniae IgA titres and coronary heart disease - Prospective study and meta-analysis

Aims To examine associations between Chlamydia pneumoniae IgA titres and incident coronary heart disease, and to compare them with associations previously reported between C pneumoniae IgG titres and coronary heart disease. Methods and Results We measured serum concentrations of C. pneumoniae IgA antibodies in 502 coronary heart disease cases and in 1005 age- and town-matched controls 'nested' in a community-based prospective study of 5661 British men (mean follow-up in controls, 16 years), and conducted a meta-analysis of published prospective studies to place our findings in context. Two hundred and twenty-one (44%) of (lie cases were in the top third of C. pneumoniae IgA titres compared with 336 (33%) of the controls, yielding an odds ratio for coronary heart disease of 1.84 (95% confidence interval 1.40 2.43) which was largely unchanged after adjustment. In aggregate, the present study and nine previously reported prospective studies of C pneumoniae IgA titres involved 2283 cases, yielding a combined odds ratio for coronary heart disease of 1.25 (1.03-1.53), with no significant heterogeneity among the ten studies (chi(9)(2)=7.8; P>0.1). This combined odds ratio is compatible with that previously reported for C pneumoniae IgG titres and coronary heart disease (1.15, 0.97-1.36). Conclusion Neither C. pneumoniae IgA titres nor IgG titres are strongly predictive of coronary heart disease in the general population. (Ear Heart J, 2002; 23: 371-375, doi:10.1053/euhj.2001. (C) 2001 The European Society of Cardiology.