Prospective study of potentially virulent strains of Helicobacter pylori and coronary heart disease in middle-aged men

Background-Studies are needed to test claims that potentially virulent stra ins of Helicobacter pylori are more strongly related to coronary heart dise ase (CHD) than are other strains. Methods and Results-We measured serum Ige antibodies to mixed H pylori anti gens and separately to the virulence-associated H pylori antigen CagA (cyto toxin-associated gene product A) in 505 CHD cases and in 1025 age-matched c ontrols "nested" in a prospective study of 7735 British men (mean duration of follow-up in controls, 16 years). Of the 505 cases, 401 (79%) were serop ositive for H pylori antibodies compared with 740 (72%) of the 1025 control s, yielding an odds ratio for CHD of 1.55 (95% CI 1.19 to 2.03), which fell to 1.30 (95% CI 0.88 to 1.90) after adjustments were made for standard vas cular risk factors and indicators of socioeconomic status. Of the CHD cases , 240 (48%) were seropositive for IgG antibodies to CagA compared with 450 (44%) of the controls. When CagA-seropositive individuals were compared wit h H pylori-seronegative individuals, the odds ratio for CHD was 1.42 (95% C I 1.06 to 1.91), which fell to 1.10 (95% CI 0.71 to 1.71) after adjustments . In an analysis restricted to the 1141 (75%) H pylori-seropositive partici pants, the odds ratio for CHD was 1.0 (95% CI 0.78 to 1.29) in CagA-seropos itive men. No strong associations were observed between H pylori seropositi vity and blood lipids, blood pressure, markers of systemic inflammation, or plasma homocysteine. Conclusions-H pylori infection is not strongly related to the incidence of CHD in late middle-aged men, and CagA-positive strains appear to be no more strongly related to the disease than other strains. However, further studi es are required to confirm or refute the existence of any moderate associat ions, particularly at younger ages.