Is there an association between Helicobacter pylori infection and coronary heart disease?

In addition to gastroduodenal diseases, Helicobacter pylori infection has been associated with extradigestive diseases, including coronary heart disease. Different studies have failed to demonstrate a clear association. The aim of this work was to carry out a meta-analysis of these studies' results, with a special emphasis on heterogeneity. A MEDLINE search of all studies published in English from 1994 to 1998 was conducted. Five criteria for eligibility of studies were defined. The quality of each study was assessed on a five-point scale adapted from studies by the Quebec Task Force. The final results are reported based on a fixed-effects model. Pooled odd ratios were calculated for subgroups of studies (defined on quality of adjustment, on confounding factors, and on the type of control population). Sixty-nine articles and abstracts fulfilling the defined criteria were analyzed. They were all case-control or cross-sectional studies. H. pylori diagnosis was carried out by serology, urea breath test or both; coronary heart disease was diagnosed mainly by coronary angiography. The total sample size was 6603. The quality score varied from 4 to 10. The pooled odds ratios of the 24 articles included in the model was 1.55 (95% confidence interval (CI): 1.38-1.74). It ranged from 1.07 to 2.34 when the quality of adjustment for confounding factors was considered and from 1.25 to 1.99 when the type of control group was considered. In any case there was significant heterogeneity (p < 0.001). The present study demonstrated a possible weak association but the high degree of heterogeneity in the studies impedes a clear demonstration.