Impact of socioeconomic status and sibling number on the prevalence of infection: a cross-sectional study in a Japanese population.

infection is a significant risk factor for gastric cancer. The infection is acquired mainly in early childhood and is influenced by environmental factors, including socioeconomic status and sibling number. However, the impact of socioeconomic status and sibling number on infection has not been well studied in Japan. We conducted a cross-sectional study to evaluate the impact of socioeconomic status, represented by education level, and sibling number on the prevalence of infection among 3,423 non-cancer subjects who visited Aichi Cancer Center between 2005 and 2013. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) using a logistic regression model adjusted for potential confounding variables. Of the 3,423 subjects, 1,459 (42.6%) were -positive. The prevalence of infection linearly decreased with increasing socioeconomic status [ORs (95% CIs) of moderate and high socioeconomic status relative to low socioeconomic status of 0.67 (0.53-0.84) and 0.43 (0.34-0.54), respectively; trend=9.7×10]. In contrast, the prevalence of infection linearly increased with increasing sibling number [ORs (95% CIs) of SN 3-4 and ≥5 relative to sibling number ≤2 of 1.74 (1.47-2.06) and 2.54 (2.12-3.04), respectively; trend=1.2×10]. This study showed that socioeconomic status and sibling number were significantly associated with the prevalence of infection.