A population-based study for difference in contribution of type 2 diabetes mellitus to cardiovascular outcomes in adult cancer survivors and general population without history of cancer
Authors: Kim K , Oh S , Lee J , Hong Y S 
Published: October 2021

Abstract

Background/Introduction
Type 2 diabetes mellitus (T2DM) is a well-established risk factor for cardiovascular disease (CVD). However, evidence is scarce on the difference in burden of T2DM as a cardiovascular risk factor in adult cancer survivors compared to the general population without history of cancer. This evidence gap needs to be addressed as increased risk for CVD in adult cancer survivors compared to the general population has been consistently reported from observational studies.

Purpose
To investigate the association of T2DM with CVD in adult cancer survivors and general population without history of cancer and compare the magnitude of associations for each population using propensity score-matched analyses

Methods
For this population-based cohort study, we used the National Health Insurance Service-National Sample Cohort (NHIS-NSC) established in the Republic of Korea (2002–2015) to identity adult cancer survivors who were aged 18 years or older and survived more than 12 months after the first-ever cancer diagnosis and general population without history of cancer matched for age and sex in a 1:1 ratio. In both cohorts, those with history of CVD prior to the index date were excluded. We used Cox proportional hazards model to compute hazard ratios (HR) and 95% confidence intervals (95% CI) for incident CVD in those with T2DM compared to those without T2DM in both adult cancer survivors and the general population after adjusting for shared confounding factors (income status, cigarette smoking, alcohol consumption, physical inactivity, body mass index, blood pressure, lipid abnormalities, family history of CVD, and aspirin use). Furthermore, we used Q statistic to compare the magnitude of association between T2DM and CVD in this matched cohort.

Results
The overall age and sex matched cohort in the NHIS-NSC comprised of 5,163 adult cancer survivors and the equivalent number of participants categorized as general population without history of cancer. The adjusted HR for CVD among adult cancer survivors with T2DM, as compared to without T2DM was 2.27 (95% CI: 1.25–4.11). Similarly, T2DM was associated with an increased risk of CVD in the general population without cancer (HR=1.88; 95% CI: 1.03–3.42). However, no strong statistical evidence was found for difference in contribution of T2DM to CVD risk between adult cancer survivors and general population without history of cancer (Pheterogeneity = 0.662).

Conclusions
In this population-based cohort study, T2DM was associated with an increased risk for CVD in both adult cancer survivors and those without history of cancer. Difference in magnitude of T2DM-CVD associations between adult cancer survivors and the general population without history of cancer was not substantial from a statistical standpoint. However, adult cancer survivor with T2DM may still need additional clinical attention for CVD prevention compared to those without history of cancer.

Funding Acknowledgement
Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Cancer Center (Republic of Korea)