Department of Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.
Department of Sociology, University of Calgary, Calgary, AB, Canada.
Int J Epidemiol. 2021 Nov 10;50(5):1498-1511. doi: 10.1093/ije/dyab067.
Compared with those with a higher socio-economic position (SEP), individuals with a lower SEP have higher cancer morbidity and mortality. However, the contribution of modifiable risk factors to these inequities is not known. This study aimed to quantify the mediating effects of modifiable risk factors to associations between SEP and cancer morbidity and mortality.
This study used a prospective observational cohort design. We combined eight cycles of the Canadian Community Health Survey (2000/2001-2011) as baseline data to identify a cohort of adults (≥35 years) without cancer at the time of survey administration (n = 309 800). The cohort was linked to the Discharge Abstract Database and the Canadian Mortality Database for cancer morbidity and mortality ascertainment. Individuals were followed from the date they completed the Canadian Community Health Survey until 31 March 2013. Dates of individual first hospitalizations for cancer and deaths due to cancer were captured during this time period. SEP was operationalized using a latent variable combining measures of education and household income. Self-reported modifiable risk factors, including smoking, excess alcohol consumption, low fruit-and-vegetable intake, physical inactivity and obesity, were considered as potential mediators. Generalized structural equation modelling was used to estimate the mediating effects of modifiable risk factors in associations between low SEP and cancer morbidity and mortality in the total population and stratified by sex.
Modifiable risk factors together explained 45.6% of associations between low SEP and overall cancer morbidity and mortality. Smoking was the most important mediator in the total population and for males, accounting for 15.5% and 40.2% of the total effect, respectively. For females, obesity was the most important mediator.
Modifiable risk factors are important mediators of socio-economic inequities in cancer morbidity and mortality. Nevertheless, more than half of the variance in these associations remained unexplained. Midstream interventions that target modifiable risk factors may help to alleviate inequities in cancer risk in the short term. However, ultimately, upstream interventions that target structural determinants of health are needed to reduce overall socio-economic inequities in cancer morbidity and mortality.
与社会经济地位较高的人群相比，社会经济地位较低的人群癌症发病率和死亡率更高。然而，可改变的风险因素对这些不公平现象的贡献尚不清楚。本研究旨在量化可改变的风险因素对社会经济地位与癌症发病率和死亡率之间关联的中介作用。
本研究采用前瞻性观察性队列设计。我们结合了加拿大社区健康调查的八个周期（2000/2001 年至 2011 年）作为基线数据，以确定一个在调查时没有癌症的成年人队列（≥35 岁）（n=309800）。该队列与出院摘要数据库和加拿大死亡率数据库相链接，以确定癌症发病率和死亡率。从完成加拿大社区健康调查之日起，对个体进行随访，直至 2013 年 3 月 31 日。在此期间，记录了个体首次因癌症住院和因癌症死亡的日期。社会经济地位通过结合教育和家庭收入衡量的潜在变量来运作。自我报告的可改变的风险因素，包括吸烟、过量饮酒、低水果和蔬菜摄入、身体活动不足和肥胖，被视为潜在的中介因素。广义结构方程模型用于估计可改变的风险因素在社会经济地位较低与癌症发病率和死亡率之间的关联中的中介作用，该模型在总人群和按性别分层的人群中进行了评估。
可改变的风险因素共同解释了低社会经济地位与整体癌症发病率和死亡率之间 45.6%的关联。在总人群和男性中，吸烟是最重要的中介因素，分别占总效应的 15.5%和 40.2%。对于女性，肥胖是最重要的中介因素。
可改变的风险因素是癌症发病率和死亡率社会经济不公平的重要中介因素。然而，这些关联的方差仍有一半以上无法解释。针对可改变的风险因素的中游干预措施可能有助于在短期内减轻癌症风险的不公平现象。然而，最终需要针对健康结构决定因素的上游干预措施来减少癌症发病率和死亡率方面的整体社会经济不公平现象。
