Interactive effect of cigarettes and coffee on daytime systolic blood pressure in patients with mild essential hypertension

OBJECTIVE: To test the hypothesis that moderate smoking (fewer than 20 cigarettes/day) and coffee consumption have an interactive effect on ambulatory blood pressure. DESIGN: A case-control study. SETTING: Patients in the multicentre Hypertension Ambulatory Venetia Study, northeastern Italy. SUBJECTS: Six hundred and forty-three men and 244 women with borderline-to-mild status (non-smokers versus smokers) and their habitual consumption of coffee (0, 1-3, or 4+ cups/day). MAIN OUTCOME MEASURES: Office blood pressure, ambulatory blood pressure, urinary adrenaline and noradrenaline levels according to smoking status, coffee consumption and their interaction. RESULTS: In the men, daytime systolic blood pressure (SBP) was significantly higher in the smokers than in the non-smokers and in the coffee drinkers than in the others. Moreover, two-way analysis of covariance revealed a significant interaction between smoking status and coffee consumption: the daytime SBP in smokers who drank 4+ cups/day of coffee was 6.0 mmHg higher than that of non-smokers who abstained from coffee. Conversely, office blood pressure was lower in the smokers than in the non-smokers and was similar in the coffee drinkers and the others. Coffee consumption had a significant effect on urinary adrenaline. Similar results were obtained in the women. CONCLUSIONS: In contrast with what is shown by office blood pressure measurement, moderate smokers and coffee drinkers with mild hypertension have significantly higher daytime SBP levels than non-smokers and those who do not drink coffee. Cigarettes and coffee have an interactive effect on daytime SBP in young patients, with mild essential hypertension.