Racial Differences in CagA Sero-prevalence in a Consortium of Adult Cohorts in the United States.

Background: Prevalence of () infection, the main risk factor for gastric cancer, has been decreasing in the United States; however, there remains a substantial racial disparity. Moreover, the time-trends for prevalence of CagA-positive infection, the most virulent form, are unknown in the U.S.

Population: We sought to assess prevalence of CagA-positive infection over time by race in the United States.

Methods: We utilized multiplex serology to quantify antibody responses to antigens in 4,476 participants across five cohorts that sampled adults from 1985 to 2009. Using log-binomial regression models, we calculated prevalence ratios and 95% confidence intervals for the association between -CagA sero-prevalence and birth year by race.

Results: African Americans were three times more likely to be -CagA sero-positive than Whites. After adjustment, -CagA sero-prevalence was lower with increasing birth year among Whites ( = 0.001), but remained stable for African Americans. When stratified by sex and education separately, the decline in -CagA sero-positivity among Whites remained only for females ( < 0.001) and was independent of educational attainment. Among African Americans, there was no difference by sex; furthermore, sero-prevalence increased with increasing birth year among those with a high school education or less ( = 0.006).

Conclusions: Among individuals in the United States born from the 1920s to 1960s, -CagA sero-prevalence has declined among Whites, but not among African Americans.

Impact: Our findings suggest a widening racial disparity in the prevalence of the most virulent form of , the main cause of gastric cancer.