Low DASH score ups CVD mortality risk in adults with genetic predisposition to smoking

Adults with a genetic susceptibility to smoking are at increased risk of dying due to a cardiovascular disease (CVD), suggest the results of the Singapore Chinese Health Study.

Furthermore, CVD mortality associated with genetically determined smoking is significantly higher among individuals with lower Dietary Approaches to Stop Hypertension (DASH) scores.

“Understanding the genetic predisposition to CVD may help to improve clinical intervention strategies,” the researchers said. “Lifestyle factors, such as diet, may differ among ethnic groups and may, in turn, modify individuals’ risks to diseases.”

Researchers from the Huazhong University of Science and Technology, China, and the National University of Singapore, Singapore, examined the genetic predisposition to ever smoking in relation to CVD mortality and assessed whether such an association could be modified by dietary intake.

Chinese adults (n=23,760) without cancer and CVD at recruitment (1993‒1998) were included in the analysis. The researchers calculated the weighted genetic risk score (wGRS) to define the genetically determined regular smoking behaviour (never or ever) and assessed the relationship between the wGRS and CVD mortality using multivariable-adjusted Cox regression models. Finally, they conducted a 1-sample Mendelian randomization analysis for ever smoking and CVD mortality.

A total of 2,301 CVD deaths occurred over a mean follow-up of 22.6 years. A significant association was found between a genetic predisposition to ever smoking and CVD mortality (adjusted hazard ratio, 1.07, 95 percent confidence interval [CI], 1.03‒1.12). [Am J Clin Nutr 2022;116:386-393]

The Mendelian randomization analysis, however, showed no causal relationship between ever smoking and CVD mortality (odds ratio [OR], 1.13, 95 percent CI, 0.87‒1.45).

Moreover, the DASH score had a significant impact on the association between the smoking wGRS and CVD mortality. The association between a genetic predisposition to smoking and CVD mortality only persisted among individuals with a low DASH score (p_interaction=0.004).

“A genetic predisposition to smoking was associated with CVD mortality in the Chinese population,” the researchers said. “In addition, we detected a significant interaction showing higher CVD mortality related to genetically determined smoking among those with lower DASH scores.”

In a recent study evaluating the CVD risk factors and outcomes of any alcohol consumption or smoking, genetically predicted alcohol intake increased high-density lipoprotein cholesterol, reduced triglycerides, and elevated blood pressure, which could influence CVD risk. In addition, smoking was found to be a risk factor for several CVDs even after adjusting for alcohol. [PLoS Med 2020;17:e1003410]

Specifically, smoking was associated with CVD outcomes such as myocardial infarction (OR, 1.84, 95 percent CI, 1.43‒2.37), coronary heart disease (OR, 1.64, 95 percent CI, 1.28‒2.09), heart failure (OR, 1.61, 95 percent CI, 1.32‒1.95), and large artery atherosclerosis (OR, 2.4, 95 percent CI, 1.41‒4.07).

“While future studies incorporating alcohol consumption patterns are necessary, our data suggest causal inference between alcohol, smoking, and CVD risk, further supporting that lifestyle modifications might be able to reduce overall CVD risk,” the authors said.