Letters to the Editor Re: "heart Rate Variability from Short Electrographic Recordings Predicts Mortality from All Causes in Middle-aged and Elderly Men: the Zutphen

I read with interest the analysis of the heart rate variability and mortality in the Zutphen Study (1). One potentially confounding factor which was not addressed is alcohol consumption. Alcohol has been traditionally associated with smoking and increased mortality as a result of a number of causes, including cancer. It is known that heart rate variability is affected by alcohol (2). Chronic alcohol consumption decreases heart rate variability; this decreased heart rate variability returns to normal after a number of days of abstinence (3). Because of this, alcohol induced decreased heart rate variability could be an important confounding factor, accounting for the apparent association of cancer with heart rate variability in this study.