Race moderates the relationship between obesity and colorectal cancer screening in women

Objective To determine if the relationship between obesity and usage of colorectal cancer (CRC) screening in women varies when stratifying by race. Methods Using nationally representative data from the 2005 National Health Interview Survey, we examined the relationship between obesity and CRC screening for white and African-American women aged 50 and older. Screening usage variables indicated if a woman was up-to-date for any CRC screening test, colonoscopy, or FOBT. We used multivariable logistic regression models that included interaction terms to determine if race moderates the obesity-screening relationship. We also calculated adjusted up-to-date colonoscopy rates using direct standardization to model covariates. Results The relationship between obesity and screening differed by race for any CRC screening test (P = 0.04 for interaction) and for colonoscopy (P = 0.01 for interaction), but not for FOBT. Obese white women had a lower adjusted colonoscopy rate (30.2%, 95% CI 25.9-34.8) than non-obese white women (39.1%, 95% CI 36.1-42.2). Obese African-American women, on the other hand, had a higher adjusted colonoscopy rate (41.2%, 95% CI 31.6-51.4) than their non-obese counterparts (35.6%, 95% CI 28.3-43.6). Overall, adjusted colonoscopy rates were lowest among obese white women. Conclusions Obesity is associated with lower CRC screening rates in white, but not African-American women.