Abstract
Since eradication of Helicobacter pylori (H. pylori) is thought to be a preventive measure against stomach cancer, several studies have examined factors associated with the infection. This paper reports the association of the infection with lifestyle factors observed in a hospital-based case-control study. Cases were 140 anti-H. pylori IgG antibody-positive outpatients (75 males and 65 females). Controls were 52 antibody-negative outpatients (22 males and 30 females). Both groups had undergone gastroscopy at Aichi Cancer Center Hospital between February 1995 and February 1997, and lifestyle data collected on the first visit were linked to calculate odds ratios. A strong association was observed with smoking among males; age-adjusted odds ratio (OR) = 7.85, 95% confidence interval (CI), 2.03-30.4. Rice breakfast (OR = 3.74; 95% CI, 1.30-10.8) and soybean paste soup (every day vs. occasionally, OR = 5.24; 95% CI, 1.80-15.2) were also associated with antibody positivity in males, but not in females. In females, pickled Chinese cabbage (> or = 1/week vs. < or = 3/month, OR = 2.82; 95% CI, 1.06-7.48) and lettuce (> or = 1/week vs. < or = 3/month, OR = 2.90; 95% CI, 1.09-7.76) were significantly associated with positivity. Multivariate analysis gave similar estimates for the above factors. Although the association between smoking and H. pylori infection has not been detected in past studies of a general population, except one recent one, this study on outpatients suggested a possible association. Smoking may work as a cofactor disturbing incidental eradication of H. pylori by antibacterial agents administered for other reasons.