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

Abstract

Aims: To examine associations between Chlamydiapneumoniae IgA titres and incident coronary heart disease, and to compare them with associations previously reported between C pneunoniae 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 the 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 (χ29=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. © 2001 The European Society of Cardiology.