Cigarette smoking is associated with chronic and acute endothelial dysfunction, and hence probably also elevated out-of-clinic blood pressure. In the present study, we investigated the association between cigarette smoking and masked hypertension defined as elevated out-of-clinic pressure but normal clinic pressure.Design and method:
Our study included male participants of the China Ambulatory and Home Blood Pressure Registry, who underwent clinic, 24-hour ambulatory and 7-day home BP monitoring. We classified smoking status as non-smoking (never smoked), past-smoking (previously smoked but stopped for at least 1 year) and current light (1–14 cigarettes/day) and heavy smoking (more than15 cigarettes/day). We defined masked hypertension as a normal clinic blood pressure (less than 140/90 mmHg) and an elevated 24-hour ambulatory (at least 130/80 mmHg) or home blood pressure (at least 135/85 mmHg).Results:
The 1782 male subjects had a mean age of 55.3 years and included 536 (30.1%) current smokers. The prevalence of masked hypertension on 24-hour ambulatory blood pressure measurement was 18.5%, 22.6%, 25.1% and 24.4% in non-smokers (n = 936), past smokers (n = 310), and current light (n = 473) and heavy smokers (n = 63), respectively (P = 0.03 for trend). After adjustment for confounders, current light and heavy smokers had a significantly (P < 0.03) higher risk of masked hypertension than non-smokers (odds ratio 1.47 [95% confidence interval, 1.02–2.11] and 1.67 [1.12–2.49], respectively). Similar trends were observed for masked hypertension on home BP measurement, although statistical significance was not achieved (P < 0.59 for light and heavy smokers versus non-smokers).Conclusions:
Cigarette smokers had elevated out-of-clinic blood pressure, and might have to be screened for masked hypertension.