- High alcohol intake is associated with coronary plaque burden among Chinese men.
- There was no evidence for a causal protective effect of moderate drinking on atherosclerosis.
Self-reported and genotype-predicted mean alcohol intake are associated with a higher burden of carotid plaque among a cohort of Chinese men, but not carotid intima-media thickness, researchers reported.
In a study of more than 22,000 Chinese adults with biobank data, the researchers also found that the genetic associations were not observed for women — among whom few drank alcohol regularly — suggesting the genetic associations in men were potentially due to the causal effects of alcohol consumption.
“Conventional epidemiological studies have consistently reported a lower risk of CVD associated with moderate alcohol consumption compared with not drinking; however, the causality of these associations in uncertain and the biases of reverse causality and residual confounding often affect conventional observational studies of alcohol intake,” Iona Y. Millwood, DPhil, senior epidemiologist and research lecturer from the Medical Research Council (MRC) Population Health Research Unit at the University of Oxford, U.K., and colleagues wrote in the study background. “Recent large-scale conventional and genetic studies suggest there is no safe drinking threshold for CVD risk, but the evidence differs across CVD types. Moreover, the associations of alcohol use with subclinical carotid arterial injury and atherosclerosis remain controversial, with both positive and J-shaped associations reported in cross-sectional studies in mainly Western populations.”
Self-reported drinking, genetic data
Millwood and colleagues analyzed data from 22,384 adults from the China Kadoorie Biobank, a prospective cohort that recruited participants aged 30 to 79 years at baseline from five urban and five rural areas of China from 2004 to 2008 (38% men). Participants self-reported alcohol use at baseline and at resurvey (2013-2014; mean age, 60 years) and also underwent carotid artery ultrasound measurements and genotyping data for aldehyde dehydrogenase type 2 (ALDH2) rs671 and alcohol dehydrogenase 1B (ADH1B) rs1229984.
Researchers categorized participants by baseline alcohol drinking status: ex-drinkers, nondrinkers, occasional drinkers and current drinkers. Current drinkers were grouped according to baseline reported alcohol intake in grams per week and by sex: less than 140 g, 140 g to 279 g, 280 g to 419 g and more than 420 g per week for men, and less than 70 g and more than 70 g per week for women.
Researchers assessed associations of carotid intima-media thickness, any carotid plaque and total plaque burden with self-reported and genotype-predicted mean alcohol intake.
The findings were published in Atherosclerosis.
At baseline, 34.2% of men and 2.1% of women reported regular alcohol drinking, with rates of 29% and 2% at resurvey, respectively. For men, mean alcohol intake among current drinkers ranged from 180 g per week to 427 g per week.
At resurvey, the mean carotid intima0media thickness was 0.7 mm for men and 0.64 mm for women and 39.1% and 26.5% of men and women had carotid plaque, respectively.
Researchers found that, for men, risk for coronary plaque increased with self-reported alcohol intake among current drinkers, with an OR of 1.42 (95% CI, 1.14-1.76) per 280 g per week of alcohol consumed. The findings were directionally consistent with genotype-predicted mean alcohol intake, with an OR of 1.21 (95% CI, 0.99-1.49).
Higher alcohol intake among men was also associated with higher carotid plaque burden in conventional analyses, with each 280 g per week of usual alcohol intake associated with a 0.19 mm higher carotid plaque burden (95% CI, 0.1-0.28) in conventional analyses and a 0.09 mm higher carotid plaque burden (95% CI, 0.02-0.17) in genetic analyses. There were no clear associations observed between alcohol intake and carotid intima-media thickness in conventional or genetic analyses.
No genetic associations for women
Researchers did not observe dose-response associations of usual alcohol intake with carotid measurements for women.
“Among women, very few drank alcohol and there were no associations of the genetic instruments with any of the three carotid measurements, suggesting that the genetic associations for carotid plaque burden among men were likely to be chiefly due to alcohol intake rather than pleiotropic genotypic effects,” the researchers wrote.
The researchers noted that CV risk factors, such as age, smoking, systolic BP and lipid levels might confound or mediate the observed associations of alcohol intake with subclinical atherosclerosis.
“We found that the association of alcohol with carotid plaque attenuated after adjusting for systolic BP and was stronger in men with higher systolic BP levels, and became slightly stronger with adjustment for LDL,” the researchers wrote. “These findings suggest that systolic BP and plasma lipid levels may potentially play a role in mediating or modifying the relationship between alcohol intake and subclinical atherosclerosis.”