Alcohol Consumption and Arterial Stiffness: A Longitudinal Study of Pulse Wave Velocity in the Whitehall II Cohort

Arterial stiffness occurs where the vessel wall lacks elasticity. It is known to be independently associated with both cardiovascular morbidity and mortality, such that it can act as a surrogate end point for studies of cardiovascular disease. Pulse wave velocity (PWV) is an index of this stiffness and has been described as its 'gold standard' measurement.

A number of other clinical factors have been found to show meaningful association with PWV, including heart rate and mean arterial pressure. These findings have highlighted the need for studies of new potential determinants of PWV to account for the potentially confounding influence of these known factors. Additional demographic and lifestyle characteristics have also been shown to act as moderators of PWV. In particular, research has demonstrated that PWV increases with age, and this stiffness is consequently deemed an indicator of vascular ageing.

Alcohol intake is another lifestyle characteristic that has been considered as a potential factor in the loss of arterial elasticity. Evidence to date suggests that a J-shaped association may exist between such intake and PWV, but this work has mostly relied on cross-sectional data or looked at short-term intake patterns only. By adopting a longitudinal perspective, further insight may be garnered into this important epidemiological issue. Consequently, the new study herein proposed will address this research need and investigate how different patterns of alcohol consumption relate to arterial stiffness and to the progression of this stiffness over time. The primary objectives of this study are to (1) examine whether long-term patterns of alcohol consumption are independently associated with a baseline assessment of carotid-femoral PWV and (2) whether alcohol intake is likewise associated with longitudinal changes in this important cardiovascular marker.

Longitudinal alcohol exposure will be determined from reported consumption at phases 1 (1985-1988) through 9 (2007-2009) of the Whitehall II Cohort Study and categorised according to the latest UK recommendations on alcohol intake limits. These guidelines define moderate consumption as weekly ethanol intake volumes of 112g or under for both males and females. As alcohol consumption is recorded in UK units in the Whitehall II database, conversion will be performed using the standard ratio of 1 unit to 8 grams of ethanol prior to categorisation. The subsequent categorisation will draw distinctions between non-drinkers and former drinkers, as well as between moderate and heavy consumers. Those with unstable patterns of consumption will also be identified as there is emerging evidence that such consumers may have a different cardiovascular risk profile compared to consumers with more longitudinally consistent intake patterns.

Demographic and clinical characteristics will be investigated to provide context for the subsequent inferential analyses. As research has also suggested that participant sex can moderate the relationship between alcohol and PWV, this will be tested in the current analysis (through preliminary modelling that includes sex as part of an interaction term with level of alcohol consumption). If this moderation effect is replicated, then our core result reporting will be stratified according to sex.