The role of access to a regular primary care physician in mediating immigration-based disparities in colorectal screening: Application of multiple mediation methods

Abstract

Background: Colorectal cancer screening participation is income, rurality, age, sex, marital status, education, and expo-lower among recent immigrants than among Canadian-sure to a provincially organized colorectal screening program. born individuals. We assessed whether this screening dis-Results: The prevalence of never having been screened was parity is mediated by access to regular primary care physi-71% and 57% in visible minority and white recent immi-cians (PCP). grants, respectively, and 46% in white Canadian-born respon-Methods: Pooling years 2003 to 2014 of the Canadian dents. If all had regular PCPs, there would be no reduction in Community Health Survey, lifetime screening in respondents the screening inequality between white recent immigrants and aged 50 to 75 years of age who immigrated in the previous 10 Canadian-born (null PE), and the inequality between visible years (n ¼ 1,067) was compared with Canadian-born respon-minority immigrants and white Canadian-born may increase dents (N ¼ 102,366). Regression- and inverse probability by 6% to 13%. weighting-based methods were used to estimate the total effect Conclusions: Ensuring all have regular PCPs may lead to (TE) and controlled direct effect (CDE) of recent immigration greater screening gains among Canadian-born than recent on never having received either a stool- or endoscopic-based immigrants. screening test. The proportion of the TE that would be elim-Impact: Improving access to PCPs may increase colorectal inated if all had a PCP was computed using these estimates screening overall, but not reduce immigration-based dispa-[proportion eliminated (PE) ¼ (TE CDE)/(TE 1)]. Anal-rities screening. Alternative interventions to reduce this dis-yses were stratified by visible minority status and adjusted for parity should be explored.