Immigration and adherence to cervical cancer screening: a provincewide longitudinal matched cohort study using multistate transitional models

Objective — Previous studies highlighting inequities in cancer screening between immigrants and non-immigrants have been methodologically limited. This longitudinal matched cohort study used a multistate modelling framework to examine associations between immigration status and cervical cancer screening adherence.

Methods — A 1:1 matched cohort of women aged 25 and older from 1992-2014 who were residing in Ontario was examined. For each woman, the proportion of time spent being non-adherent was determined. Disparities in cervical screening adherence, and specifically the association between immigration status and the rate of becoming adherent, were investigated with a three-state transitional model. The model was adjusted for individual- and physician-level characteristics, which were updated annually and incorporated as time-varying covariates.

Results — The matched cohort consisted of 1 156 720 immigrant and non-immigrant women. The median proportion of time spent non-adherent was 38.9% for immigrants and 24.7% for non-immigrants. The rate of becoming adherent among immigrants was lower than that among non-immigrants, after accounting for individual- and physician-level characteristics (relative rate 0.933; 95% CI 0.928-0.937). Other characteristics such as socioeconomic status, immigrant region of origin, presence of primary physician, and physician's sex were found to be significantly associated with cervical screening adherence.

Conclusion — This study assessed the association between immigration status and adherence to cervical cancer screening. The insights from this work can be used to target groups of women vulnerable to underscreening and to minimize their time spent non-adherent to cancer screening. The methodology serves as a useful framework for examining adherence to other types of cancer screening.