Coffee Drinking Is Longitudinally Associated With Increased Risk of Hypertension in Young Individuals With Elevated Sympatho-Adrenergic Activity.

Objective: The relationship between coffee consumption and risk of hypertension in humans has been inconclusive. This may be due to individual characteristics that can confer susceptibility to develop hypertension in some individuals. The objective of this study was to determine whether sympatho-adrenergic tone modifies the association between caffeinated coffee intake and risk of hypertension in subjects screened for stage 1 hypertension. Design and method: HARVEST is a prospective longitudinal study of people aged 18 to 45 years screened for stage 1 hypertension. 640 of the 1204 subjects enrolled were included in the sympatho-adrenergic sub-study. During 24-hour ambulatory BP monitoring, urine was collected for 24-hour Norepinephrine and Epinephrine assessment. Catecholamines were measured by high-performance liquid chromatography and normalized by 24-hour creatinine output (mcg/g). High and low sympatho-adrenergic activity was identified according to whether catecholamine level was above or below the median. Results: Among the participants, 27.2% were coffee abstainers, 63.7% were moderate coffee drinkers (1-3 cups/day) and 9.1% were heavy drinkers (>3 cups/day). During a 19-year follow-up, 80.9% of the participants developed established hypertension. The risk of hypertension associated with coffee intake greatly differed according to sympatho-adrenergic activity. In a 2x2 Cochran Mantel-Haenszel sub-table the coffee-related odds ratios for hypertension were much higher among the participants with high sympatho-adrenergic tone than in those with low sympatho-adrenergic tone (p=0.0006 for Norepinephrine and =0.0001 for Epinephrine). In a multivariable Cox analysis, including several confounders and other risk factors, coffee consumption was a significant predictor of hypertension only among the participants with high sympatho-adrenergic tone (for Norepinephrine, HR, 1.52 (95%CI, 1.12-2.05) in moderate drinkers, and 2.60 (1.57-4.28) in heavy drinkers; for Epinephrine, 1.34 (0.97-1.85) in moderate drinkers and 1.83, 1.11-3.04 in heavy drinkers) while no increase in risk was found in those with low sympatho-adrenergic tone (all p=n.s.). Conclusions: The present data indicate that coffee intake is associated with increased risk of hypertension only among individuals with elevated sympatho-adrenergic activity. This finding can explain the inconsistency of existing data on the relationship between chronic coffee consumption and development of hypertension as this association is present only in predisposed individuals.