Abstainers and Coronary Heart Disease: Are Unknown Risk Factors to Blame?

Epidemiological studies have found that coronary heart disease (CHD) is much less common in light drinkers than in abstainers. To examine whether unknown risk factors might explain this finding, researchers in Finland compared 1161 life-long abstainers with 27,311 light drinkers (those who drank <6 drinks per week). Analyses were adjusted for potential confounders (e.g., sex, age, income).

• Of the 16 potential CHD risk factors examined, only low body mass index (BMI) and low leisure-time physical activity were more prevalent among abstainers than among light drinkers (odds ratio [OR] 1.3 for BMI <20 versus 20–24.9; OR 1.3 for the lowest amount of exercise versus the highest amount).
• Five of the risk factors (smoking, insomnia, anxiety, low reward for work effort, and adverse life events) were less prevalent among abstainers (ORs ranging from 0.2 to 0.8).

Comments:

To exclude alcohol use as the reason for less CHD in light drinkers, an unknown risk factor would have to be much more prevalent in abstainers than in light drinkers. None of the 16 CHD risk factors examined in this study met this criterion. Nonetheless, the possibility of a multifactorial or other unknown explanation remains possible.

It should be noted that these findings differ from those of a recent American study, probably because nondrinkers in this Finnish cohort were lifetime abstainers rather than previous drinkers who may have quit due to poor health. Given the abundance of observational studies on moderate drinking, only a well-designed randomized controlled trial could provide more definitive evidence.

Peter D. Friedmann, MD, MPH

Reference:

Poikolainen K, Vahtera J, Virtanen M, et al. Alcohol and coronary heart disease risk–is there an unknown confounder? Addiction. 2005;100(8):1150–1157.