ALCOHOL INTAKE AND BLOOD-PRESSURE - THE IMPORTANCE OF TIME ELAPSED SINCE LAST DRINK

Background A positive association of chronic exposure to alcoholic bev erages with blood pressure and the prevalence of hypertension has been described in epidemiological surveys, but the influence of time elaps ed since last ingestion in this setting was not demonstrated. Design A cross-sectional, population-based survey. Methods In total 1089 adult s from Porto Alegre, randomly selected from a population-based, multi- stage probability sample, were interviewed at home. The average daily alcohol intake of each subject was calculated taking into account the concentration of ethanol in the beverages (distilled or fermented beve rages), and the time elapsed between the last ingestion of ethanol and the moment of blood pressure determination. Standardized sitting bloo d pressure and anthropometric parameters were collected. The magnitude and shape of the associations were analyzed considering blood pressur e as a continuous variable and the prevalence of arbitrarily defined h ypertension. Simple and multiple linear regression models, including m odels to identify nonlinear associations, with quadratic and cubic ter ms of the amount of alcohol consumed, were employed. Blood pressure me ans were compared by analysis of variance and analysis of covariance. The association between hypertension and exposure to ethanol was analy zed through logistic regression models, controlling for various potent ial confounders. Results Positive nonlinear associations of the amount of alcohol consumed with blood pressure and the prevalence of hyperte nsion (greater than or equal to 160/95 mmHg) were found, independent o f age, years of education, smoking, and use of oral contraceptive and antihypertensive drugs. The consumption of 30 g/day ethanol was associ ated with increases of 1.5 and 2.3 mmHg in diastolic and systolic bloo d pressures, respectively, far men, and 2.1 and 3.2 mmHg, respectively , for women. The prevalence of hypertension was higher among those ing esting more than 30 g/day (odds ratio = 2.9, P< 0.01). The time elapse d between the last ingestion and blood pressure measurement was indepe ndently associated with the prevalence of hypertension. Men with last consumption of alcohol 13-23 h prior to measurement had odds of being hypertensive 2.6 (confidence interval 1.3-5.0) greater than did subjec ts who had consumed alcoholic beverages 24 h and more before the blood pressure determination. For men, systolic and diastolic blood pressur es were lower during the first 3 h after ingestion and increased after ward. Frequency of consumption and type of beverage consumed were not independently associated with level of blood pressure. Conclusion A ti me-dependent association between alcohol consumption and effects on bl ood pressure, demonstrated in experimental studies, was found for free -living individuals selected at random. (C) 1998 Rapid Science Ltd.