Patients with CRC are predisposed to CVD due to shared risk factors and sequalae of cancer treatments. We aimed to assess if rural residence and low SES modify the risk of developing new-onset CVD in patients with CRC.
Patients diagnosed with stage I-III CRC without any baseline CVD in a large Canadian province from 2004 to 2017 were identified using the population-based registry. Postal codes were linked with Census data to determine rural residence as well as SES. Low income and low education were defined as <46,000 CAD/annum and a neighborhood population in which <80% attended high school. The presence of myocardial infarction, heart failure, arrythmia or cerebrovascular accident constituted as CVD.
We identified 12,170 eligible patients. The median age was 65 years and 43.7% were women. Stage I, II and III CRC were diagnosed in 30.2%, 31.4% and 38.5% patients. One-fourth of patients resided rurally, while 78.8% and 59.5% belonged to low income and low education neighborhoods. At a median follow-up of 62.2 months, 4,163 (34.2%) developed new-onset CVD, which was more common in patients from rural communities (36.8% vs 33.3%, P<.001), low income (35.7% vs 28.8%, P<.001) and low education (36.0% vs 31.6%, P<.001) neighborhoods. After adjusting for age, sex and treatment, low income (odds ratio [OR], 1.22; 95% confidence interval [CI], 1.10-1.37; P<.001) and low education (OR, 1.10; 95% CI, 1.01-1.20; P=.044) were associated with a higher likelihood of developing CVD, while rural residence was not. In a Cox regression model adjusting for measured confounders, low income (hazard ratio, 1.14; 95% CI, 1.03-1.25; P=.010) but not low education and rural residence predicted for worse overall.
In this large population-based study, patients from low SES neighborhoods were at an increased risk of developing new-onset CVD. However, the effect on survival was attenuated, likely reflecting access to universal healthcare in Canada. SES disparities in physical activity, diet, and other lifestyle modification strategies may explain the different risk profiles for CVD and should be the focus of public health efforts.
The authors.
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All authors have declared no conflicts of interest.