Driving environment in Iran increases blood pressure even in healthy taxi drivers

BACKGROUND : Nowadays, driving is an unseparated part of our new modern lifestyle; and we are exposed to this environment all the days for several hours whether as drivers or as riders. Many reports indicated that Iran is on the top rank of automobile-related morbidity and mortality among developed and even many developing countries that can be due to dangerous driving habits in Iran. We designed this study to find out if environment of driving have clinically important effects on blood pressure (BP) and how strong is the effect. We also examined if there were any predictors for the BP rises in driving time. METHODS : In a cross-sectional study, 31 healthy male taxi drivers were included through a multistage proportional sampling method in winter and spring 2007. They were referred to the clinic of hypertension in Shafa Hospital, Kerman. A trained nurse measured the BPs. She also did set up the Ambulatory Blood Pressure Monitor (ABPM) on the drivers’ left arms for BP recording every 30 minutes during the day. Based on the diurnal recorded BPs, the subjects were allocated into normotensive and hypertensive (systolic BP > 135 or diastolic BP > 85mmHg) groups. The difference among the clinic BPs and the driving BPs was examined by t-test in Stata version 8, followed by a multivariate analysis for exploring the main predictors for BP rises in driving time. RESULTS : Both mean systolic and mean diastolic BPs were significantly increased from 116.85 (SE 2.28) and 74.44 (SE 2.22) mmHg in clinic to 138.64 (SE 2.77) and 95.70 (SE 2.55) mmHg during driving, respectively (P = 0.0001). Pulse pressure remained constant (P = 0.87). The difference between clinic's and driving time measurements was higher in hypertensive group. Those with higher systolic blood pressures in clinic had more frequent and higher BP rises in driving time (P = 0.02). CONCLUSIONS : Driving increased BP averagely 20 mmHg especially in those with higher BP measurements. Drivers with higher baseline systolic BPs were more prone to higher BP rises in driving time. KEYWORDS : Driving, systolic blood pressure, diastolic blood pressure, hypertension, ambulatory blood pressure monitoring.