Cigarette smoking and blood pressure in a worker population: a cross-sectional study

BACKGROUND: Cigarette smoking has been reported to cause an acute increase in blood pressure (BP). Nevertheless, many epidemiological studies have found lower average BP values in smokers than in non-smokers. The aim of this study was to evaluate the possible existence of a systematic difference in BP values between smokers and non-smokers in a worker population. METHODS: We studied 7109 employees of a metallurgical factory, all men, aged 18-60 years, 3237 non-smokers and 3872 smokers; of the latter, 816 smoked less than 10 cigarettes per day (light smokers), the others smoked 10 or more cigarettes per day. Clinical examination included measures of resting BP (by mercury sphygmomanometer), heart rate (HR) (by pulse palpation), body weight and height. Data were adjusted for age and body mass index (BMI). Four age groups (18-30, >30, >40 and >50 years) and 3 BMI groups (< 25, 25-30, >30) were considered. RESULTS: In smokers, the adjusted values of systolic BP (SBP) and HR (127.72 mmHg and 75.16 beats/min, respectively) were slightly but significantly higher than in non-smokers (127.1 mmHg, P < 0.05 and 72.64 beats/min, P < 0.001), whereas diastolic BP (DBP) was significantly lower (83.37 versus 84.31 mmHg, P < 0.001). Considering the amount of cigarettes smoked, the mean BP values of light smokers were not significantly different from those of subjects smoking 10 or more cigarettes per day, whereas HR mean values were significantly higher in the latter. The prevalence of hypertension (WHO criteria) was similar in smokers and non-smokers in each age group. CONCLUSIONS: Our data showed slightly but statistically higher SBP and HR, and lower DBP mean values in smokers than in non-smokers; however, the differences in BP, although significant from the statistical point of view, were not of actual clinical significance