Incidence of colon cancer among Medicaid beneficiaries with and without HIV under comparable colorectal cancer screening patterns

Abstract Background People with HIV (PWH) in the US have a lower incidence of colon cancer compared to the general population. The lower incidence may be explained by differences in receipt of screening. Thus, we sought to estimate colon cancer incidence under scenarios where Medicaid beneficiaries, with and without HIV, followed the same screening protocols. Methods We used data from 1.5 million Medicaid beneficiaries enrolled in 14 US states, 2001-2015, who were aged 50-64; 72,747 beneficiaries had HIV. We estimated risk of colon cancer and death by age, censoring beneficiaries when they deviated from 3 screening protocols, which were based on Medicaid’s coverage policy for endoscopies during the time period: receive one endoscopy every (1) two, (2) four, and (3) 10 years. We used inverse probability weights to control for baseline and time-varying confounding and informative loss to follow-up. Analyses were run overall, by sex, and by race/ethnicity. Results PWH had a lower incidence of colon cancer than beneficiaries without HIV. Compared to beneficiaries without HIV, the risk difference at age 65 was -1.6% (95% CI: -2.3, -0.7) lower among PWH under the two-year protocol and -0.8% (95% CI: -1.3, -0.3) lower under the ten-year protocol. Results were consistent across subgroup and sensitivity analyses. Conclusions Our findings suggest that the lower risk of colon cancer that has been observed among PWH aged 50-64 compared to those without HIV is not due to differences in receipt of lower endoscopy.