Area-level income disparities in colorectal screening in Canada: evidence to inform future surveillance.

A Blair,Geetanjali D Datta,L Gauvin,S Ouédraogo

doi:10.3747/co.26.4279

Abstract

Participation in colorectal screening remains low even in countries with universal health coverage. Area-level determinants of low screening participation in Canada remain poorly understood. We assessed the association between area-level income and two indicators of colorectal screening (having never been screened, having not been screened recently) by linking census-derived local area-level income data with self-reported screening data from urban-dwelling respondents to the Canadian Community Health Survey (50-75 years of age, cycles 2005 and 2007, n = 18,362) who reported no known risk factors for colorectal cancer. Generalized estimating equation Poisson models estimated the prevalence ratios and differences for having never been screened and having not been screened recently, adjusting for individual-level income, education, marital status, having a regular physician, age, and sex. About 53% of the study population had never been screened. Among individuals who had ever been screened, 35% had been screened recently. Adjusting for covariates, lower area-level income was associated with having never been screened [covariate-adjusted prevalence ratios: 1.24 for quartile 1; 95% confidence limits (cl): 1.16, 1.34; 1.25 for quartile 2; 95% cl: 1.15, 1.33; 1.15 for quartile 3; 95% cl: 1.08, 1.23]. Among individuals who had been screened in their lifetime, area-level income was not associated with having not been screened recently. Lower area-level income is associated with having never been screened for colorectal cancer even after adjusting for individual socioeconomic factors. Those findings highlight the potential importance of socioeconomic contexts for colorectal screening initiation and merit attention in both future research and surveillance efforts.

Highlights

Colorectal cancer is currently the 3rd most common cause of cancer death in Canada, and yet only 20% to 30% of average-risk adults are up-to-date on colorectal screening—either by stool test in the preceding 2 years or by endoscopic testing in the preceding 5 or 10 years[1,2]
Lower area-level income is associated with having never been screened for colorectal cancer even after adjusting for individual socioeconomic factors. Those findings highlight the potential importance of socioeconomic contexts for colorectal screening initiation and merit attention in both future research and surveillance efforts
That screening participation rate is much lower than the rate observed for breast cancer (63% participation) or cervical cancer (79% participation) despite Canada’s universal health care coverage[3]

Summary

Introduction

Colorectal cancer is currently the 3rd most common cause of cancer death in Canada, and yet only 20% to 30% of average-risk adults (that is, Canadians with no known familial or medical risk factors) are up-to-date on colorectal screening—either by stool test in the preceding 2 years or by endoscopic testing in the preceding 5 or 10 years (sigmoidoscopies and colonoscopies, respectively)[1,2]. In trying to understand the factors that operate to keep population-level colorectal screening participation so low, extant Canadian literature has identified several determinants, including social and demographic factors such as age, marital status, visible minority or immigration status, educational attainment, household income, and area of residence (rural vs urban)[4,5]; health service–related factors such as having access to a regular physician or primary care service and receiving a screening recommendation e128. Canadian studies have yet to examine the independent association of community- and local area–level factors with participation in colorectal cancer screening, as has been done in other countries[10,11,12,13]. Given limitations in data availability, those studies did not examine associations independent of individual-level confounding factors such as income. Participation in colorectal screening remains low even in countries with universal health coverage. Area-level determinants of low screening participation in Canada remain poorly understood

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Discussion

Conclusion