
 cardiovascular diseases ( cvds ) account for nearly a third of all deaths worldwide .
the key intervention in cvds is to identify risk factors early and initiate therapy to control them .
hence , diagnosis of hypertension and appropriate treatment to optimize bp are important public health goals worldwide .
all groups of professional drivers especially those carrying passengers are at excess risk of htn , myocardial infarction , and hemorrhagic stroke [ 26 ] .
traffic congestion , exposure to vehicle exhausts , constant whole body vibration , poor condition of roads , poor town planning and traffic regulation , over speeding due to competition between buses , and carelessness of pedestrians contribute to their misery . besides , most of the drivers are in the habit of eating main meals from hotels and consuming snacks ( often oily and fried ) and fast food items between trips .
no study has been published regarding the prevalence of htn or special risk factors among professional bus drivers in india . in this context
, we aimed to estimate the prevalence of htn and to identify its risk factors among male occupational bus drivers of kozhikode , a city in kerala , south india .
this cross - sectional study was carried out in the corporation bus stand , kozhikode , one of the busiest bus stands in kerala .
the approximate prevalence of htn among males in kerala as determined in previous studies is 35% [ 79 ] .
but we decided to study all male bus drivers enlisted in the corporation bus stand giving consent to participate in the study .
those who reported violent physical exercise , smoking , tobacco chewing , or drinking tea or coffee within thirty minutes prior to bp measurement were excluded .
information about their medical history , lifestyle , and occupation was obtained by personal interview using a pretested semistructured questionnaire .
bp was measured manually using a mercury column sphygmomanometer and stethoscope by the auscultatory method .
two readings were taken one before and one after the interview , and the two were at least 15 minutes apart .
patients with bp in prehypertensive and hypertensive range were asked to report one week later and another set of readings was obtained for confirmation .
we measured the subjects ' height and weight , from which the body mass index ( bmi ) was calculated .
the weight was measured ( closest to 1  kg ) using a beam type weighing scale .
height was measured ( nearest to 1  cm ) with the subject in an erect position against a vertical surface .
hypertensives were referred for medical care and prehypertensives were advised lifestyle modification and bp monitoring .
htn was defined as systolic bp of 140  mm  hg and/or diastolic bp of 90  mm  hg or current pharmacological treatment for htn .
pre - htn was defined as systolic bp 120139  mm  hg and/or diastolic bp 8089  mm  hg .
isolated systolic htn was defined as systolic bp 140  mm  hg in presence of a normal diastolic bp .
aware  of htn status if he reported a diagnosis of htn made by a medical practitioner .
 treatment for htn  was defined as regular use of a prescription medication for htn .
 control of htn with treatment  was defined as sbp and dbp less than 140  mm  hg and 90  mm  hg , respectively , in a subject on regular antihypertensive therapy .
never smoked  was assigned to subjects who never smoked cigarettes or beedis and  current smokers  to those who smoked at any time during past one year .
quit smokers  were those who had quit smoking at least one year before the study . the smoking habit was quantified in pack - years ( number of packets of cigarettes smoked per day multiplied by the duration of smoking in years assuming that each packet contains 20 cigarettes ) . based on alcohol use
( <3 days per week ) , or  takes alcohol on most days  ( 3 days per week ) . ethical clearance for the study
mean age of the population was 36.52  8.38 ( sd ) years ( range 2160 years ) .
mean number of family members each subject supported was 4.93  1.71 ( range 211 ) .
mean number of children per married couple was 1.89  1.03 ( range 06 ) .
mean number of years for which the study subjects were in the job of bus driving was 14.6  8.27 years ( range 138 ) . on most days they worked for a mean duration of 11.56  1.87 hours ( range 516 ) .
the mean sbp and dbp of the study population were 126.66  13.74  mm  hg ( range 100 to 172 ) and 83.66    10.18  mm  hg ( range 60 to 110 ) , respectively .
the mean sbp was 122.19  12.53  mm  hg and 130.25  13.65  mm  hg , respectively , for subjects with age up to 35 years and subjects older than 35 years .
similar values for dbp were 80.45  9.75  mm  hg and 86.25  9.83  mm  hg , respectively .
the mean bmi of the study population was 22.77  2.97  kg / m ( range 16.14 to 34.15 ) .
the systolic and diastolic bps of study subjects increased with age ( for sbp , r = 0.306 , p < .01 ; for dbp , r = 0.289 , p < .01 )
. the mean values of sbp and dbp were significantly higher in subjects older than 35 years ( for sbp , t = 4.12 , p 0.000 ; for dbp , t = 3.94 , p 0.000 ) .
when the bps of the subjects were classified according to jnc7 criteria , 16.8% ( 30/179 ) ( 95% ci = 11.222.3 ) had normal bp , 41.9% ( 75/179 ) ( 95% ci = 34.649.7 ) had prehypertension , and 41.3% ( 74/179 ) ( 95% ci = 34.149.2 ) had htn .
isolated systolic htn was seen in 6.70% ( 12/179 ) ( 95% ci = 3.410.6 ) individuals .
the distribution of the jnc7 categories and isolated systolic htn in each age group is shown in table 2 .
the association between htn and various presumed sociodemographic , medical , personal , behavioral , occupational , and dietary risks factors is shown in tables 3 , 4 , and 5 .
proportion of the study population belonging to each category of bmi and their distribution according to jnc7 categories of bp are shown in table 6 .
taking the cut - off point for high bmi to be 25  kg / m , hypertension was associated with high bmi ( chi - square = 5.451 ; p = 0.02 ) . however , on assuming the cutoff point to be 23  kg / m , the level of significance increased ( chi - square = 8.656 ; p = 0.003 ) .
there was significant association between longer duration of employment as bus driver and hypertensive status .
hypertensives were employed for a mean duration of 16.4  8.22 years , while nonhypertensives were employed for 13.40  8.10 years ( student 's t - test .
t = 2.48 , p = 0.014 ) . in the study population , 7.26% ( 13/179 ) ( 95% ci = 3.4611.06 ) were self - reported diabetic patients among whom 61.54% ( 8/13 ) ( 95%
the mean values of systolic ( 134.08  18.55  mm  hg ) and diastolic ( 87.54  12.49 ) bps were higher in diabetics compared to the remainder . however , no statistically significant association could be discerned between htn and diabetes mellitus .
age > 35 years , being married , supporting more than 4 family members , taking main meals from restaurants on most working days , eating egg on most days , bmi  23  kg / m , and longer duration of employment as bus driver were strongly associated with htn on bivariate analysis .
binary logistic regression was done with these risk factors and current smoking and being diabetic as independent variables ( due to strong epidemiological association with htn in previous studies ) as independent variables and htn as dependant variable .
age > 35 years ( p = 0.015 ) , bmi  23  kg / m ( p = 0.007 ) , supporting more than four family members ( p = 0.011 ) , and taking main meals from restaurants on most working days ( p = 0.017 ) were independently associated with htn .
out of 74 hypertensive individuals , 12.16% ( 9/74 ) ( 95% ci = 4.7219.6 ) were aware of their hypertensive status , while only 4.05% ( 3/74 ) ( 95% ci = 0.008.54 ) were treated and only 1.35% ( 1/74 ) ( 95% ci = 0.003.98 ) had bp adequately controlled .
no significant association was found between awareness about htn and educational qualification ( chi - square-0.033 , p = 1.000 ) .
through our study we aimed to report the prevalence and special risk factors of htn among occupational bus drivers , a particularly vulnerable group .
the only other study on transit vehicle operators in india deals with htn among autorickshaw drivers of nagpur among whom the reported prevalence was 35.14% .
only two studies have been published from south asia on htn in drivers . in one study ,
23% of bus drivers were found to be hypertensive compared to 15.85% of the normal population .
another study conducted by saleekul et al . in bangkok observed the prevalence of diastolic htn to be 17.5% against 7.7% of controls . but
professional drivers especially those carrying passengers were found to be at an increased risk of stroke , attributed to htn and stress .
the overall prevalence of htn in the study group is much higher than the reported pooled prevalence of about 1620% in india [ 1719 ] . in the general population also
, the prevalence of htn is higher in kerala compared to the rest of india .
this has been attributed in previous studies to an advanced state of epidemiological transition existing in kerala [ 79 ] .
reported a htn prevalence of about 30% among males aged 3059 years in kumarakom , a relatively rural area in kerala .
another study conducted in chemmaruthy , varkala , a rural area , gives htn prevalence of 31.2% among males 2059 years old .
a third study reports a prevalence of 56.3% among urban males aged 4060 years which is comparable to our finding of 54.5% in the same age group .
this shows that prevalence of htn among bus drivers is higher than the rural population in kerala but similar to that observed in urban population of comparable age .
the near urban prevalence of htn in them could be due to the drivers acquiring life style risk factors seen in urban population .
this may be due to the habits associated with the job . among subjects with age
up to 35 years , 21 ( 26.3% ) were hypertensive , which is also high .
the genetic predisposition among indians for acquiring cardiovascular risk factors early in life , coupled with the unhealthy lifestyle , could be the cause of high htn prevalence in the young [ 20 , 21 ] .
jnc7 suggests that poor sbp control is one factor responsible for the unacceptably low rates of overall bp control .
the proportion of prehypertensives in a middle aged urban population of thiruvananthapuram was about 36% .
the study from kumarakom reported pre - htn rate of 48.3% , while only 15.3% had normal bp . in our study , only 16.8% of the study population had normal bp .
the same has been proven in a recent study conducted among residents of rural kerala .
the responsibility of supporting more than four family members was found to be associated with htn . supporting a larger family
the possibility of drivers working overtime to meet their financial needs was considered , but average work hours among the two groups were same .
probably , having to support a large family caused a degree of mental stress and anxiety which contributed to the risk of htn .
the association of htn with dietary sodium intake and fat content and protective role of fruits and vegetables is known .
most of the bus drivers leave their home early in the morning to start work .
there may be practical difficulties in preparing tiffin early in the morning . in spite of a person carrying tiffin
, he may not get adequate time , space , or other facilities to enjoy his homely meal , during a short stoppage in a long trip . to circumvent this problem ,
most drivers are forced to take meals from restaurants , whose food often contains excess salt , oil ( the same oil may be used repeatedly for deep frying which is harmful ) , spices , and other additives to make it more palatable .
there was significant association between prevalence of htn and being overweight ( bmi  25  kg / m ) .
it is seen that morbidity and mortality due to cvds in indians are higher in people with lower bmi when compared to western population .
so , some have advocated a cutoff point of 23  kg / m for normal bmi among indian population . in the current study , when the cutoff point for high bmi was made 23  kg / m , the significance levels increased .
some of the studies have reported duration of employment as a risk factor [ 6 , 12 ] .
many studies have attributed the higher prevalence of htn among bus drivers to job stress especially while working in heavy traffic ( a  work barrier  which causes risky behavior or needs extra effort ) , factors in the occupational environment , erratic work hours , sedentary lifestyle , and a sense of underpayment [ 2 , 46 , 15 ] .
there are also studies that say that there is no association between stress and htn , while some others report inverse association between self - reported stress and htn [ 19 , 23 ] . in our study
, we explored this aspect with self - reported traits like getting irritated often , frequently involving in heated exchanges , rash driving , previous involvement in accidents , and subjective feeling of adequate sleep and exercise .
explanations that have been given for this inconsistent association between stress and htn include adverse situations making a person angry which facilitates development of htn and htn altering perception of the degree of stress .
. however , we could not find any association between the two in the present study .
in addition , our study population was relatively young , about 70% being below 40 years . around middle age , many bus drivers tend to leave the vocation . in the young
, type 2 diabetes is asymptomatic and often goes undiagnosed unless blood sugar is estimated .
our study relied entirely on subjects ' self - reporting of diabetes if previously detected .
61.54% of diabetics were having htn in our study , a figure comparable to the kumarakom study . we observed that diabetics have higher mean values of systolic and diastolic bps .
we analyzed the relation between htn and ( a ) smoking status ( current smokers versus nonsmokers and quit smokers ) as well as ( b ) degree of exposure estimated as pack - years of smoking .
it may be possible to clarify the relation by studying a larger sample of the population .
consumption of fish on most days was found to be protective against development of htn in one study , likely explanation being the higher content of polyunsaturated-3-fatty acids in fish .
this could be because , majority of the population under study are habitual fish eaters .
( 96% ) , so that the protective effect could not reveal itself for lack of contrast .
the levels of awareness , treatment , and adequate control of bp are poor in india compared to the west . in the study from rural kerala , 20.6% of men were aware of their hypertensive status , 16.4% were treated , and 4.6% had their bp controlled .
these figures were 33.7% , 22.8% , and 8% , respectively , among urban males of kerala .
awareness about htn ( 12.1% ) among bus drivers is lower than the above values .
the proportion of hypertensives receiving treatment and having their bp reduced to target levels is very low .
this low level of awareness , treatment , and optimal control of bp is unacceptable considering the high literacy level of kerala .
poor awareness about htn may reflect ( a ) lack of frequent contact with the health system ,
( b ) deficits in routine clinical examination on patients , or ( c ) a lower degree of overall awareness about cvds , risk factors , and prevention .
one of our limitations was not measuring the abdominal circumference which correlates better with htn than bmi .
employing a questionnaire which will objectively assess the driving habits and compare the stress levels with other occupations will provide more insight into the factors contributing to htn .
similar studies should be conducted on a larger scale at multiple centers and involving more refined techniques and expertise to yield better results .
to conclude , the prevalence of htn among male bus drivers of kerala is very high . a close - to - urban unhealthy lifestyle acquired as part of their job lies at the heart of the problem .
they are at risk of developing coronary artery disease , stroke , and chronic kidney disease in future .
this will cause significant mortality and morbidity , reduce economic and social participation , and burden their family as well as the nation 's health system .
all occupational drivers should be screened for lifestyle diseases at entry into the vocation and then periodically .
those at risk should be rehabilitated to protect their own health and to ensure the safety of passengers .
the study underscores the pressing demand for targeted educational interventions , regular health checkups , and appropriate lifestyle modifications among bus drivers .
 
 background . 
 hypertension is a leading cause of morbidity and mortality worldwide . 
 we aimed to evaluate the prevalence of hypertension in a population of male bus drivers in north kerala , india . 
 methods . 
 the study population included male bus drivers of corporation bus stand kozhikode , kerala . 
 blood pressure , height , and weight of subjects were measured , and relevance was obtained using a structured questionnaire . results . 
 age varied from 21 to 60 years ( mean 36.5  8.4 ) . among 179 bus drivers studied , 16.8% ( 30/179 ) had normal bp , 41.9% ( 75/179 ) had prehypertension , and 41.3% ( 74/179 ) had hypertension . 
 isolated systolic htn was seen in 6.70% ( 12/179 ) individuals . 
 out of 74 hypertensives , 9 ( 12.1% ) were aware of their hypertension , while 3 ( 4.0% ) were medicated and only 1 ( 1.3% ) had bp adequately controlled . 
 age > 35 years ( p = 0.015 ) , bmi  23  kg / m2 ( p = 0.007 ) , supporting more than four family members ( p = 0.011 ) , and taking main meals from restaurants on most working days ( p = 0.017 ) were independently associated with htn in binary logistic regression . 
 conclusion . 
 prevalence of hypertension was high among bus drivers . 
 age > 35 years , elevated bmi , supporting a large family , and dietary habits associated with the job showed significant association with hypertension . 
 primary and secondary prevention strategies need to be emphasized in this occupational group . 
1. Introduction
2. Methods
3. Results
4. Discussion