Name of the candidate and address. Pabba lakshmi priya

“A STUDY TO FIND OUT CARDIOVASCULAR RISK IN INDIAN BUS DRIVERS BY MEASURING THEIR WAIST TO HEIGHT RATIO”

A variety of anthropometric indices have been used as a proxy for total fat or abdominal fat to assess risk for diseases, particularly cardiovascular diseases and diabetes. The most widely recognized is the Body mass index (BMI). Although this measure is correlated with total body fat, it does not distinguish fat from muscle or between different body fat distributions ¹

In the mid-20th century it was first observed that individuals with a central fat (android shape) distribution were at greater health risk than those with peripheral fat (gynoid shape) ^{2, 3.}It has only been accepted in the last two decades that health risks (predominantly CV and diabetes) can be determined as much by the relative distribution of the excess fat as by its total amount.

The use of imaging techniques such as computed tomography (CT) ⁴ and MRI ^{1, 5} indicated that the ‘unhealthy apple shape’ is associated with a preferential deposition of fat in the internal, visceral fat depots rather than the external, subcutaneous fat depots, this fat distribution being characteristic of the more ‘healthy pear shape ^4.

An attempt to assess relative fat distribution was made with the ratio of waist circumference (WC) to hip circumference. This was shown to be a good predictor of health risk and was popular for many years⁶. However, although very useful for risk assessment, waist-to-hip ratio is not helpful in practical risk management because both waist and hip can decrease with weight reduction and so the ratio sometimes changes very little.

It was not until the end of the last century (1995) that Waist circumference by

itself was proposed as an alternative proxy for central or abdominal obesity ⁷.

Waist circumference is strongly correlated with abdominal fat measures from

advanced imaging techniques, and thought to represent fat stored in visceral depots. However waist circumference may over- and under-evaluate risk for tall and short individuals with similar WC.

At about the same time, several researchers independently proposed the waist-to-height ratio (WHtR) as another proxy for central obesity, correcting the Waist circumference for the height of the individual ^8-12. Similar to Waist circumference, Waist to height has been strongly correlated with abdominal fat measured using imaging techniques ^1,36.

Other devices-such as measuring skinfold thickness, ¹³bio-impedance analysis⁴⁵ and near infra–red spectroscopy⁶¹—are available and relatively inexpensive, but they have not always been completely validated and their reliability and sensitivity in less than fully standardized conditions is questionable⁶².In the absence of a technological solution, therefore, the emphasis has been on anthropometric measures of body mass and body-fat distribution

If an anthropometric index is to be used in a public health context and be used for screening, it is invariably useful to invoke cut-off or boundary values. The correlation of Waist circumference for height offers the advantage that it is possible that a single Waist to height boundary value may be useful in different ethnic, age and sex groups ¹⁴, while WC requires population-specific boundary values ^15.

Research shows that the Waist to height, not BMI, is the most accurate assessment tool for health risk^{54, 55}. People with the most weight around their waists are at greatest risk of diseases such as heart disease and diabetes. The most dangerous

place to carry weight is in the abdomen. Fat in the abdomen, which is associated

with a larger waist, is metabolically active and produces various hormones that can cause harmful effects, such as type-2 diabetes, elevated blood pressure⁴⁶, and altered lipid (blood fat) levels⁵³.

The best advice is, since, as a mature adult, we can't change our height, we should take special care to keep our weight and especially our abdominal girth in a

Healthy range by eating nutritiously and exercising regularly. By all means, check

Our waist measurements frequently to measure our progress, and then adjust our eating habits accordingly. And, go for regular medical checkups and discuss our

Particular situation freely with our doctor. 

6.2NEED OF THE STUDY

The occupation of driving is associated with an increased risk of cardiovascular disease^{16, 17, 18}. Studies in recent decades have demonstrated that workers in the transportation industry are at greater risk of an incorrect diet and sedentary behavior ^19,20. Bus drivers particularly have higher mortality, morbidity, and absenteeism rates due to obesity ^21,22.

Changes have also been occurring in the type of occupation in which workers are engaged, with a move from high-activity to low-activity occupations²³. The clinical characterization of Professional bus drivers revealed a high frequency of cardiovascular risk factors, as obesity, Hypertension, hyperlipidemia, and hyperglycemia, as well as contributing functional Characteristics, such as a low-intensity activity, sedentary behavior, long duration in a sitting Position, and high-calorie diet, which lead to excessive weight gain and associated Co- morbidities²⁴.

The work shift is also a risk factor of chronic disease, including cardiovascular disease and metabolic disorders, due to the altered circadian rhythm, changes in

lifestyle, tension, and stress at work i.e. driving ^{25, 26,27}.

A study carried out in the United States involving more than 600 thousand workers found the highest prevalence of obesity to be among male employees who work in highway transportation services (31.7%) ²⁸. In other study, done on professional bus drivers the prevalence of overweight and obesity was even higher, as more than half of the population of drivers (57.5%) was characterized as overweight and approximately 20% was considered obese, totaling 77.5% of the

Sample²⁹. Similar results are reported in another study involving Brazilian truck

drivers, which found prevalence values of 47.8% and 16.2% for overweight and

obesity, respectively ³⁰.

Besides increasing cardiovascular risk, obesity in this group of individuals leads to an increase in health costs related to traffic accidents³¹. Obesity as a coronary heart disease risk factor has been implicated along with driver’s irregular eating habits, low levels of physical activity at work and at leisure ³².

Carbon monoxide, sulphur dioxide and nitrogen oxides present in vehicle fumes, have been confirmed in escalating Coronary heart Disease risk for bus drivers^47,48.

In a study 69% of bus drivers rated traffic, as a job stressor, to be a regular or major problem⁴⁹ .Not only has psychological strain been noted for general drivers in traffic congestion,⁵⁰ but physiological reactions in bus drivers have been also established⁵¹. Indeed, it is time pressure and impediments to the driver's primary task that makes congestion such a stressor especially where time urgency is apparent⁵³. Prolonged job strain is said to predict high levels of coronary heart diseases³³.

Abdominal circumference is a widely used measure for the distribution of fat, as it is indicative of the buildup of visceral adipose tissue or intra-abdominal fat, which, in some cases, may be more harmful than overweight and obesity in general ³⁴. According to the National Institutes of Health, the cutoff point for abdominal

circumference in the male gender is 102 cm ³⁵.

Waist to height is an important surrogate marker of the distribution of adiposity in the abdominal region in men³⁶. Accordingly, we propose that Waist to height is probably the most convenient and reliable clinical measure of abdominal fat compartments^37-38.

The present study is to measure their waist to height ratio to find out cardiovascular risk in Indian bus drivers who travel from medium to long distance in different work shifts. Bus drivers are provided with handouts which contains exercise programme for their risk factor modifications.

1) C. Bigert, P. Gustavsson, J. Hallqvist et al.,(2003) in their study on “Myocardial infarction among professional drivers Epidemiology'', They concluded that Professional drivers are at an increased risk of myocardial infarction but the underlying causes for this increased risk are uncertain.¹⁹

2) M. A. Winkleby, D. R. Ragland, et al.,(1988) in their study on “Excess risk of sickness and disease in bus drivers: a review and synthesis of epidemiological studies'', concluded that bus drivers have higher rates of mortality, morbidity, and absence due to illness when compared to employees from a wide range of other occupational groups.²²

3) C. Bigert, K. Klerdalet al,(1977-96) in their study on “Time trends in the incidence of Myocardial infarction among professional drivers in

Stockholm,” Occupational and Environmental Medicine (2004), stated on time trends in the incidence of first myocardial infarction (MI) among bus, taxi, and lorry drivers in Stockholm.¹⁷

4) P. D. Wang and R. S. Lin,(2001) “Coronary heart disease risk factors in urban bus drivers,” suggested that exposure to the occupation of driving a bus may carry an increased risk of CHD and that drivers who develop signs of cardiovascular illness should be transferred to non-driving occupations within the company.¹⁸ 

5) J. P. Després, B. J. Arsenault, et al, (2008).In their study on “Abdominal obesity: the cholesterol of the 21st century?” They suggested that exposure to the

occupation of driving a bus may carry an increased risk of coronary heart disease

and that drivers who develop signs of cardiovascular illness should be transferred to non-driving occupations within the company.²⁴

6) Hedberg G, Jacobsson K A, et al. (1993). In their study on "Risk indicators of

Ischemic heart disease among male professional drivers in Sweden". Their results showed that significantly more drivers than referents were overweight, smokers, and shift workers; were sedentary in their leisure time; and had a work situation characterized by high demands, low decision latitude, and low social support³²

7) Morris et al. 1953a, b, 1966; Heady et al. (1961).Study on "Coronary heart disease and physical activity of work". Morris and his employees found 80 cases of coronary heart disease (angina pectoris, myocardial infarction and immediate mortality from CHD) in 30,726 person-years for drivers, and 31 cases in 19,166 person-years for conductors. Statistical tests suggest that, the distribution of the various types of first presentation of coronary heart disease differs in the conductors of central buses from that of the drivers of central buses; likewise, the distribution of cases in the tram and trolleybus conductors differs from that in their drivers.^59,60

9) Michaels &Zoloth, (1991); Stern, Halperin, &McCammon, (1988) ,In their

study on "Mortality among Urban Bus Drivers", they said that Carbon monoxide,

sulphur dioxide and nitrogen oxides present in vehicle fumes, have been confirmed in escalating Coronary heart disease risk for bus drivers.⁴⁷

10) Björntorp P(1988) study on "The associations between obesity, adipose tissue distribution and disease", Concluded that obesity and abdominal distribution of adipose tissue constitute two separate entities with different pathogenesis, clinical consequences and probably treatment.⁶

11) Dalton M, Cameron AJ et al,(2003) study on “Waist circumference, waist-hip ratio and body mass index and their correlation with cardiovascular disease risk factors in Australian adults", They concluded that Waist circumference, BMI and WHR identified different proportions of the population, as measured by both prevalence of obesity and cardiovascular disease (CVD) risk factors. Whilst WHR had the strongest correlations with CVD risk factors before adjustment for age, the three obesity measures performed similarly after adjustment for age. Given the difficulty of using age-adjusted associations in the clinical setting, these results suggest that given appropriate cut-off points, WHR is the most useful measure of obesity to use to identify individuals with CVD risk factors.³⁹

12)S.D. Hsieh, H. Yoshinaga (1995) study on "Abdominal fat distribution and coronary heart disease risk factors in men- waist/height ratio as a simple and useful predictor ".They concluded that Waist/height ratio, an index of abdominal obesity, may be a better predictor of multiple CHD risk factors in men than waist/hip ratio in mass epidemiologic studies.⁹

13) J AtherosclerThromb,et al.( 2002),study on "Waist-to-height ratio is the best predictor of cardiovascular disease risk factors in Japanese schoolchildren". They concluded that W/Ht ratio is the best predictor of cardiovascular risk factors in

Japanese schoolchildren. They propose using W/Ht ratio for detecting cardiovascular disease risk in children.⁵⁷

14)Schneider HJ, KlotscheJ,et al, (2011) “Measuring abdominal obesity: effects of height on distribution of cardio-metabolic risk factors risk using waist circumference and waist-to-height ratio”. They found that short subjects have higher levels of risk factors and a 30% higher prevalence of the metabolic syndrome than tall subjects if grouped by WC but not if grouped by WHtR. These findings support our hypothesis that risk stratification by WC is biased by height. They suggested   that WHtR instead of WC should be implemented in obesity guidelines and in the definition of the metabolic syndrome.⁵⁴

15)Browning LM, Hsieh SD, Ashwell M (2010).In their study on, “A systematic review of waist-to-height ratio as a screening tool for the prediction of cardiovascular disease and diabetes: 0.5 could be a suitable global boundary

Value”. They concluded that waist to height ratio as a predictor of diabetes, CVDandrelated risk factors, and the usefulness of the global boundary value of 0.5, will encourage the use of this index.⁵⁸

• 
  To find out cardiovascular risk in Indian bus drivers by measuring their waist to height ratio.
  
• 
  To create awareness about importance of exercise in maintaining their health and cardiovascular fitness.
  

1. 
   STUDY DESIGN AND SETTING
   

1. 
   STUDY DESIGN:
   

2. 
   SOURCES OF DATA:
   

3. 
   PLACE OF STUDY:
   

2. 
   METHODOLOGY
   

1. 
   POPULATION:
   

2. 
   SELECTION CRITERIA:
   

• 
  All bus drivers engaged in active service.
  
• 
  Bus drivers who are willing to participate in the study.
  

• 
  Smokers and alcoholics.
  
• 
  Bus drivers associated with co-morbid condition and its medications.
  

• 
  300 subjects.
  

• 
  Permission for conducting the study from the KSRTC and APSRTC management Bangalore division will be obtained prior to the study.
  
• 
  Informed consent will be obtained from each subject for screening.
  
• 
  Height and waist will be measured using standardized units by measuring tape.
  
• 
  Driver’s health screening will be conducted at bus depot premises in liaison with the KSRTC and APSRTC management.
  

The Waist-to-Height ratio is determined by dividing the waist circumference by the height. Waist-to-Height ratios of 0.5^42-45or greater are indicative of intra-

abdominal fat for both men and women and are associated with a greater risk of cardiovascular disease and values above 0.6 indicate substantially increased risk ^41.

Waist to height is measured to find out their cardiovascular risk. It will be

Calculated by dividing the waist (in inch) by height (in inch).A value of 0.5 is

Considered as boundary cutoff value^42-44.

The following chart helps to determine if the Waist to height falls in a healthy range (these ratios are in percentages)^40.

Men:

• 
  Ratio less than 35: Abnormally Slim to Underweight
  
• 
  Ratio 35 to 43: Extremely slim
  
• 
  Ratio 43 to 46: Slender and Healthy
  
• 
  Ratio 46 to 53: Healthy, Normal, Attractive Weight
  
• 
  Ratio 53 to 58: Overweight
  
• 
  Ratio 58 to 63: Extremely Overweight/Obese
  
• 
  Ratio over 63: Highly Obese
  

• 
  Single time study
  
• 
  No follow up
  

• 
  Paper
  
• 
  Pen
  
• 
  Measuring Tape
  
• 
  Handouts
  

• 
  No, this study does not require any intervention.
  

Yes it has been obtained from my institution.

Ethical clearance form is attached as appendix (I).

The informed consent will be obtained prior to the study from each subject and is attached as appendix (II).

.

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