Original Article
Cardiovascular Risk Factors in Tobacco-chewers: A Controlled Study
BK Gupta, A Kaushik, RB Panwar, VS Chaddha, KC Nayak, VB Singh, R Gupta, S Raja

Abstract

Background : Influence of habitual tobacco chewing on cardiovascular risk has not been well studied. To determine prevalence of major cardiovascular risk factors in subjects who habitually chew tobacco we performed a controlled study.

Methods : A population based case-control study was performed in Bikaner in North-western India where the prevalence of tobacco-chewing is high. Successive 200 subjects who agreed to participate in the evaluation and had a history of isolated tobacco-chewing (range 10-60 years) were enrolled (Group III). The prevalence of major coronary risk factors- obesity, truncal obesity, hypertension, fasting hyperglycemia, and lipid levels were estimated using current guidelines. Electrocardiogram was also performed in all subjects. Chest radiography and treadmill stress test was done in subjects when indicated by symptoms. 200 age- and gender-matched controls who did not use tobacco in any form (Group I) and 200 subjects who had history of smoking bidis or cigarettes for more than 10 years (range 10-55 years) (Group II) were also evaluated.

Results :
The body-mass index and obesity were lowest in smoker group. Tobacco chewers had a significantly higher (p<0.001) systolic blood pressure (BP), diastolic BP, resting heart rate, total cholesterol, LDL cholesterol and triglycerides as compared to controls and was similar to smoker group. There was a significantly greater (p<0.01) prevalence of hypertension, hypercholesterolemia, hypertriglyceridemia, radiographic cardiomegaly and positive stress test in Group III as compared to controls. Prevalence of these risk factors was similar among Group II and Group III subjects. HDL cholesterol levels were the lowest in tobacco-chewing group (44.3+8.1 mg/dl) as compared to the Group I (48.4+7.8) and Group II (47.4+7.5) (p<0.001).

Conclusions : There is a significantly greater prevalence of multiple cardiovascular risk factors obesity, resting tachycardia, hypertension, high total and LDL cholesterol, and low HDL cholesterol, and electrocardiographic changes in tobacco users, chewing or smoking, as compared to tobacco non-users. Chewing tobacco is associated with similar cardiovascular risk as smoking. ©

INTRODUCTION
According to the World Health Report (2002) tobacco is the most important preventable cause of overall mortality as well as cardiovascular mortality worldwide.1 While cigarette smokers are found worldwide smokeless tobacco use is restricted to certain geographic areas.2 Tobacco use is widely prevalent in India and many developed countries. Multiple studies have reported that all forms of tobacco use (smoked, smokeless and other forms) is highly prevalent in youth and adult and in both men and women in India.3 Tobacco chewing is a unique habit of Indian subcontinent and is consumed in form of pan, gutka, mawa, khaini, mainpuri, etc. Because of its easy availability tobacco chewing is rapidly increasing and affecting all age groups, genders and has become a major public and social health concern. It is roughly estimated that about 5 to 10 million people are tobacco-laced pan masala addicts in India.4
Cigarette smoking is a major risk factor for coronary heart disease and ischaemic stroke, lung cancer, chronic obstructive lung disease and premature morbidity and mortality.5 In India smoking has been correlated with increased mortality from pulmonary tuberculosis.6 Nicotine is one of the important substances present in tobacco and has direct toxic effects on cardiovascular system.5,7 Tobacco chewing is well known to increase risk of oral and gastrointestinal cancers but whether it increases the risk of cardiovascular diseases is not well studied.4 To study the cardiovascular risk factor profile in subjects chronically exposed to chewing tobacco and to compare the risk factors in smokers and control subjects we performed a study.
METHODS
The study was approved by the institutional ethics committee and was conducted in the department of medicine, SP Medical College and Associated Group of Hospitals, Bikaner, Rajasthan. Fifteen health check-up camps were organised in the city of Bikaner in years 2001 and 2002 to evaluate cardiovascular risk factors in community. Preliminary talks were held with local community leaders who were explained the aims, objectives and methodology of the study. Volunteers who agreed to use of chewing tobacco and non-smokers, smokers who did not chew tobacco and non-tobacco users were invited for participation in the study.
Successive subjects who consumed tobacco in chewable form (gutka, paan, khaini, are the most popular forms in this region) for more than 10 years were included in the study. These subjects did not use smoke and were not suffering from any major illness. The prevalence of risk factors in these subjects was compared with smokers of more than 10 years (cigarette or bidis) who did not consume chewable tobacco (n=200), and healthy controls (n=200). Exclusion criteria were subjects with history of alcohol intake, ingestion of recreational drugs or any drug with cardiovascular effects. Patients with known diabetes mellitus, renal disease, hepatic disease or endocrinal disorder were also excluded from the study.
After taking consent the subjects were advised to report to the camp site after 8 hours fasting and abstaining from tobacco use in any form. All the subjects were evaluated with detailed history, complete general and cardiovascular physical examination, and fasting blood sample for glucose, urea, creatinine, cholesterol, triglycerides, high density lipoprotein (HDL) cholesterol and low density lipoprotein (LDL) cholesterol. Electrocardiogram was also performed in all subjects.
Chest radiography and treadmill stress test was done in subjects when indicated by symptoms.
Cardiovascular risk factors were compared in 200 successive subjects who agreed to consume chewing tobacco and not smoking for more than 10 years (Group III), with 200 subjects who did not chew tobacco but smoked tobacco in any form (Group II), and 200 subjects who did not consume tobacco in any form (Group I).
Statistical analysis: Numerical variables are reported as mean + 1 SD and ordinal variables in percent. Unpaired t-test or chi-square test were used to compare two groups while analysis of variance and chi-square tests were used to compare multiple groups. P value less than 0.05 was considered significant.
RESULTS
The baseline demographic variables are shown in Table 1. The groups were matched for age and gender distribution. Among smoker Group II, the average consumption of cigarette/bidis per day was 18.5/day (range 10-40/day) and mean duration of smoking was 23.4 years (range 10-55 years). In Group III subjects, the average consumption of tobacco was 5.7 g/day (range 3-20 g) and mean duration of tobacco use was 21.1 years (range 10-60 years). There were no significant differences in the socioeconomic status and educational status of the subjects. The prevalence of leisure-time physical activity was lower in smokers and tobacco chewers although this was not statistically significant. Significantly greater tobacco using subjects agreed to family history of tobacco use. Although no subject presented with any symptom, upon direct questioning many subjects agreed to symptoms of chest pain (17%, 32.5%, 39%), breathlessness (2.5%, 15%, 13.5%), abdominal pain (0.5%, 1%, 5%), backache (1%, 4%, 3%), headache (1.5%, 2%, 5%), palpitations (1.5%, 5%, 6%) and recurrent stomatitis (0%, 1%, 6%). As compared to control subjects in Group I, in Group II and Group III subjects the symptoms of chest pain (34 vs. 63 vs. 78, p<0.01), breathlessness (5 vs. 30 vs 27, p<0.01), headache (3 vs. 4 vs. 10, p<0.05) and palpitations (3 vs. 10 vs. 12, p<0.05) were significantly greater.
The mean body-mass index (BMI) was significantly lower in smokers (22.1+4.4 kg/m2) as compared to controls (24.6+6.9) and tobacco chewers (24.4+4.2) (Table 2). The waist-hip ratio was similar in all the three groups and there was no difference in the prevalence of truncal obesity. Mean systolic BP and diastolic BP were the lowest in control subjects and were significantly greater and identical in Groups II and III. Systolic BP was 129.0+14.7 mm Hg in Group I, 133.5+14.1 in Group II and 131.5+17.1 in Group III and diastolic BP was 82.4+10.7, 85.4+7.7 and 87.0+9.8 mm Hg respectively (p<0.01 on within group and inter-group comparison). Prevalence of systolic as well as diastolic hypertension was also significantly greater in Group II and III subjects as compared to controls. Resting tachycardia was also significantly greater in Group II and III subjects (Table 2).
Biochemical variables are shown in Table 3. There was no significant difference in mean fasting blood glucose levels. Mean levels of total cholesterol, LDL cholesterol and triglycerides were significantly greater and not significantly different in Group II and Group III subjects as compared to controls (p<0.001). Levels of HDL cholesterol were not significantly different. Prevalence of hypercholesterolemia and hypertriglyceridemia was also significantly greater in tobacco consuming groups. Prevalence of abnormal electrocardiograms as well as coronary heart disease diagnosed by Rose-questionnaire angina or ECG changes (Q-waves, ST segment changes, T-wave changes) was also greater in Group II and III subjects as compared to controls. Radiographic cardiomegaly was seen more frequently in Group II and Group III although the numbers of subjects where radiographs were obtained was small. Treadmill stress test using standard Bruce protocol was performed in 44 subjects in Group I, 67 subjects in Group II and 62 subjects in Group III. As compared to control Group I (6 subjects, 13.6%), the treadmill stress test was indicative of ischemic response (ST depression >1.0 mm in > 2 leads) in a significantly greater proportion of subjects in Group II (20 subjects, 29.8%) and Group III (15 subjects, 24.2%) (p<0.01).
Statistical comparison of various parameters shows greater prevalence of various cardiovascular risk factors in tobacco users, smokers or chewers as compared to tobacco non-users but the comparison between tobacco chewers and smoker was found to be insignificant statistically except in HDL where we found significantly low values of HDL in tobacco chewers as compared to smokers (p<0.003) (Table 4).
DISCUSSION
The habit of chewing tobacco is increasing because of its free availability, cheaper cost and increasing education about well established hazards of smoking. Studies have confirmed that use of smokeless tobacco is as harmful as smoked tobacco.7 Chewing tobacco could result in significantly greater deleterious cardiovascular effects due to a larger overall exposure owing to prolonged absorption.8,9
Gajalakshmi et al6 performed a large case-control study in Chennai recently and reported that tobacco is a major risk factor for mortality. Gupta et al performed10 a prospective cohort study of tobacco use and mortality in Mumbai and found similar results. Our study shows that tobacco-chewers are at a high risk of mortality from cardiovascular diseases due to greater prevalence of multiple cardiovascular risk factors.
In the present study it is observed that tobacco chewing as well as smoking was more prevalent among the lower socioeconomic status subjects (Table 1). There was also a greater incidence of family history of tobacco use among these groups. This is similar to previous Indian studies.11,12 The BMI in smokers was significantly lower as compared to tobacco chewers and non-smokers. This could be due to the fact that chewing tobacco does not interfere with eating as much as smoking does and the subjects that chew tobacco may have different eating habits. We have not inquired dietary details of the study subjects and cannot comment on this aspect. Systolic as well as diastolic BP was greater in tobacco consuming groups although the diastolic BP was significantly greater in tobacco chewers. This could be due to a more prolonged absorption of tobacco when chewed accompanied with more prolonged vascoconstriction. Greater sodium content of smokeless tobacco may also be a contributing factor. Greater hypertension and mean BP levels among cigarette and bidi smokers has been reported from India and association of non-smoked tobacco with hypertension is recognized.13,14 Both smokers as well as tobacco chewers have a higher total and LDL cholesterol and triglyceride levels as compared to controls. Dietary factors to explain this difference need further studies. The higher levels of cholesterol and triglycerides in tobacco chewers may be attributed to tobacco induced stimulation on metabolism of free fatty acids in peripheral tissue.5 Similar findings have been reported earlier.15
The World Health Report (2003)16 concludes that consumption of tobacco products are the worldÊs leading preventable cause of death, responsible for about 5 million deaths a years mostly in poor countries and poor populations. The toll will double in 20 years unless available and effective interventions are urgently and widely adopted.
Removal of major risk factors such as tobacco could increase healthy life expectancy in every region of the world and would reduce the differences between different regions.17 20 major risk factors for ill-health and death contribute globally to 47% of premature deaths and 39% of total disease burden in the year 2000.18 Removal of these risk factors which includes tobacco addiction would increase global healthy life expectancy by 9.3 years (17%) ranging from 4.4% (6%) in the developed countries and 16.1 years (43%) in developing countries of Africa.
We also found a significantly greater prevalence of multiple cardiovascular risk factors obesity, resting tachycardia, hypertension, high total and LDL cholesterol, and low HDL cholesterol, and electrocardiographic changes in tobacco users, chewing or smoking as compared to tobacco non-users. Chewing tobacco is associated with similar cardiovascular risk as that of smoking. Tobacco use in any form should be the major area of concern in India and elsewhere.

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