The leading cause of mortality in Malaysia is coronary heart disease (CHD). Several ... Key words: Cigarette smoking, male youth, cardiovascular risk factors.
Malaysian Journal of Public Health Medicine 2013, Vol. 13(1): 28-36
ORIGINAL ARTICLE CIGARETTE SMOKING AND CARDIOVASCULAR RISK FACTOR AMONG MALE YOUTH POPULATION Raihan K, Azmawati MN Department of Community Health, Universiti Kebangsaan Malaysia Medical Centre (UKMMC), Malaysia.
ABSTRACT The leading cause of mortality in Malaysia is coronary heart disease (CHD). Several cardiovascular (CVD) risk factors contribute to this problem and smoking is one of the main modifiable risk factor. Most of the patients started smoking early during youth period. This study aimed to determine the association and to predict the cigarette smoking and cardiovascular risk factors among the male youth. A cross sectional study was conducted by self-administered data sheets, physical examinations: blood pressure measurement and body mass index calculation, blood taking procedure for blood glucose, total cholesterol and HDL-C levels. The results showed that the glycemic status was significantly associated with smoking status (p=0.048) however, there was no significant association for smokers and risk of developing diabetes mellitus compared to non smokers although smokers had higher odd ratio (OR: 4.33; 95%CI: 0.900-20.811) (p=0.068). Interestingly, for daily exposure of smoking, those who smoke 5 cigarette and less was significantly associated with high systolic blood pressure (p = 0.036) and smoking showed protective trend against systolic hypertension (OR: 0.57; 95% CI: 0.266-1.230), however, it was not significant (p=0.152). In conclusion, smoking among youth and its association with the cardiovascular risk factor should be addressed tactfully and early screening should be promptly done among the smoking youth for early prevention. Key words: Cigarette smoking, male youth, cardiovascular risk factors.
INTRODUCTION Non-communicable diseases (NCDs) are the leading cause of mortality and morbidity globally1. In 2008, of the 57 million death occurred worldwide, 36 million were due to NCDs, namely cardiovascular diseases as the leading cause, followed by cancers, diabetes and chronic respiratory diseases1. Cardiovascular disease (CVD) as the major contributor towards this NCDs epidemic is of global health concern1. Similarly in Malaysia, in National Health and Morbidity Survey (2006), the leading cause of mortality in both genders is CVD2. Cigarette smoking is one of the leading causes of premature peripheral, coronary and cerebral artherosclerotic vascular diseases1. The risk of myocardial infarction is increasing in one to threefold among current smokers1.The pathophysiology of smoking explained this process in which cigarette smoking is positively associated with increased blood pressure in relation with its acute effects of vasoconstriction2. Higher prevalence of hypertension was reported among the smokers than in non smokers 3, however, no specific study on prevalence among youth smokers was done. Smoking also associated with higher serum cholesterol and lower concentrations of high density lipoprotein (HDLC) when compared with
non smokers3. The risk of developing type 2 diabetes mellitus among youth was 49% and higher among the male smokers compared to the male non smokers4. For youth that already had the type 1 diabetes mellitus, the risks of developing complications of diabetes was accelerated among the youth who smokes5. Thus, cardiovascular risk profile among youth who smokes is worse compared to non smoker and this will eventually exposed them to get the coronary heart disease earlier in their adulthood. Majority of the smokers started smoking during early adult years3. The earlier they start to smoke, the more likely they are to become regular smokers3. The prevalence of current smoking among youth in Thailand was 11.4 %, in South Korea (6.6 %) and Taiwan (6.5 %)6. With the prevalence of smoking among youth (21.5%), smoking is a major problem among youth in Malaysia1-3. In a recent survey by the Ministry of Youth and Sports (2004) on negative behaviours among 5,860 youth, 80% indicated that they had ever experienced smoking 7. From the Third National Health and Morbidity Survey conducted in 2006, the national prevalence of smoking among adults 18 years and above was 21.5%, male smoking rate was many fold higher (46.4%) than that of female (1.6%)3,8. A study revealed that smoking plays an important
Malaysian Journal of Public Health Medicine 2013, Vol. 13(1): 28-36 role in precipitating atherosclerosis in both males and females in terms of small low-density lipoprotein (LDL). It showed that there was a prominent decrease in LDL particle size in male youth due to presence of testosterone hormone which might contribute to higher cardiovascular risk in males’ children and adolescents9. Malaysian Global Youth Tobacco Survey conducted in 2003 found that one in three youth have ever smoked cigarettes, while a significantly higher rate was found in males (53.6%) than females13. Nonetheless, several studies pointed that males are at higher risk of cardiovascular events than females5-8. This justify the male adolescents were chosen in this study. The aim of this study is to determine the prevalence of smoking among male youth and to determine and predict the association between cigarette smoking and cardiovascular risk factors.
MATERIALS AND METHODOS This cross sectional study was conducted within the state of Selangor where it has nine districts. Hulu Langat district was chosen out of nine. In Hulu Langat there are seven sub-districts and five of them namely Ampang, Cheras, Kajang, Semenyih and Hulu Langat were selected. The number of traditional villages and housing estates for each district were required by using the list of residential units obtained from the Ampang Jaya Municipal Office (MPAJ), Kajang Municipal Office (MPKJ) and the Hulu Langat District Health Office. From this lists, by using Fisher random numbers, the housing area from each district was selected by stratified sampling. From the selected sampling, all males adolescents aged 19 to 24 years old were recruited to participate in this study. A sample of 251 male youth aged 19 to 24 years old were selected and this was in line with the sample size calculated with the Fleiss JL formulae by using rates of smoking among youth in Thailand of 26.7% which included the nonresponse samples. All males’ were included in this study since none of them met the exclusion criteria which were, having chronic illnesses such as ischaemic heart diseases, diabetes mellitus, dyslipidemia, other metabolic disorders and other cardiovascular related illnesses, those who took any medications that can alter the blood lipid levels or had received treatment for any type of dyslipidemia, and those having haemophiliac or blood disorders.
Each participant were informed and explained thoroughly regarding objectives of the study and the benefits to take part in the study during home visit. A standardized assisted and guided data sheets form was prepared with close questions for the main cardiovascular risk factors which included demographic data such as age and ethnicity, lifestyles such as smoking status (number of cigarettes per day and duration of smoking) and metabolic parameter such as blood glucose and lipid profile, systolic and diastolic blood pressure and body mass index calculation. Physical examination Weight and heights were measured without shoes and with light clothing, and body mass index was calculated as body weight (kg) divided by the square of height (m2). Blood pressure was measured three times using the appropriate sizes of cuffs and a standard sphygmomanometer, after the subject had been seated for at least 10 minutes. For analysis, the last two measurements were averaged. Biochemistry analysis A blood sample was drawn using rapid test for lipid and glucose. The blood collected was for random blood glucose, plasma total cholesterol (TC) and High Density Lipoprotein (HDL-C) cholesterol. Definition of variables “Current smoking” was defined as current use, at the time of the survey, of cigarettes smoking since other form of smoking (using pipes, cigars or chewing tobacco) was rare in youth population, ex-smoker was defined as a person already quit smoking for the past 6 months and non smoker was a person who never takes up smoking. ‘Number of cigarettes per day’ was defined as the number of cigarettes currently smoked per day (current exposure). The dependent variables were the cardiovascular risk factors; hypertension (systolic and diastolic), total cholesterol, HDL-C and diabetic status. In this study, based on World Health Organization/International Society of Hypertension 200710, systolic ≥ 140 mmHg and diastolic ≥ 90 mmHg was defined as high. The total cholesterol level and HDL-C level were defined according to National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP 2002)11, total cholesterol ≥5.2 mg/dL is classified as high and for HDL-C, if < 1.03 mg/dL is regarded as low level. As diabetic status, based on WHO guidelines stated for blood glucose level, ≥ 7.1 is classified as high glycemic status12. Body mass index (BMI) was defined
Malaysian Journal of Public Health Medicine 2013, Vol. 13(1): 28-36 according to World Health Organization 200412 and categorized into Underweight (< 18.5 kg/m2), Normal (18.50 – 24.99 kg/m2), Overweight (25.0 – 29.99 kg/m2) and Obese (≥ 30.00 kg/m2). Statistical analysis All analyses were conducted by using SPSS Version 19.0. Data were expressed as percentages. Comparisons between groups were analyzed using chi-squared test. Simple logistic models were used to assess the crude association of each variable. Ethics The protocol of this study was approved by research and ethics committee of National University of Malaysia Medical Centre (UKMMC). Consent form was obtained from the male youth respondent before they answered the
questionnaire procedure.
and
agreed
for
blood
taking
RESULTS Baseline characteristics Baseline characteristics of the 251 participants (male youth) are shown in Table 1. The prevalence of current smoker in this population was 46.6% (n = 118) and 47.8% of them was non smoker (n = 120). Majority of the smokers were Malay with 84.1% and the remaining was non Malay (15.9%) and most of them were in 19 to 21 years of age. Among the smokers, the average number of cigarettes smokes per day was 10 sticks. Two fifth of them was overweight and obese. Majority of them had normal systolic and diastolic blood pressure, normal glycemic status and total cholesterol level, however, half of them had low HDL-C level.
Malaysian Journal of Public Health Medicine 2013, Vol. 13(1): 28-36 Table1. Demography and cardiovascular risk factors characteristics among male youth Characteristics
Mean (SD)
Age 19-21 22-24
21.3(1.65)
Ethnicity Malay Chinese Indian BMI Underweight Normal Overweight Obese Blood Pressure Systolic BP Normal High
Number (%) n = 251
139(55.4) 112(44.6) 211(84.1) 26(10.4) 14(5.6)
22.8(5.09)
125.7(13.10)
Diastolic BP Normal High
76.4(10.21)
Glycaemic Status Normal High
4.2(1.66)
50(19.9) 123(49.0) 49(19.5) 29(11.6)
215(85.7) 36(14.3) 227(90.4) 24(9.6)
241(96.0) 10(4.0)
Smoking Status Current Smoker Non Smoker Ex Smoker
118(46.6) 120(47.8) 13(5.6)
No. of cigarettes per day
9.9(6.76)
Duration of smoking
5.2(3.82)
Total Cholesterol level (mmol/L) Normal Abnormal
4.0(1.24)
HDL-C level (mmol/L) Low Normal
1.5(0.50)
212(84.5) 39(15.5)
Association between smoking and cardiovascular risk factors Among the smokers, majority of them had high glycemic status (6.8%) compared to non smokers (1.7%) (p=0.048) (Table 2). And those who smoked had higher risk to develop systolic hypertension compared to non smoking (OR: 4.33; 95% CI: 0.900-20.811) (p = 0.068) (Table 4). In Table 3, majority of the low exposure (less than 5
132(52.6) 119(47.4) sticks per day) and high exposure (more than 6 sticks per day) smokers were having normal systolic blood pressure and those who smoke 5 and less cigarette per day was associated with high systolic blood pressure (p = 0.036). Smoking also showed protective trend against systolic hypertension compared to non smoking although it was not significant (OR: 0.57; 95% CI: 0.2661.230) (p = 0.152) (Table 4).
Malaysian Journal of Public Health Medicine 2013, Vol. 13(1): 28-36 Table 2. Association of smoking status and cardiovascular risk factors among male youth Cardiovascular risk factors Smoking
Systolic blood pressure High Normal
Diastolic blood pressure High Normal
Glycemic status
Total cholesterol
HDL-C level
Body Mass Index
High
Normal
Abn
Normal
Low
Nm
Un
Nm
Ovr
Ob
Yes (n, %) (n = 118)
13 (10.3)
7 (5.1)
9 (6.8)
109 (93.2)
17 (13.7)
101 (86.3)
66 (56.4)
52 (43.6)
24 (50.0)
59 (51.3)
24 (52.3)
13 (48.1)
No (n, %) (n = 120) X2 , p value
20 100 (16.7) (83.3) 2.09, 0.149
60 60 (50.0) (50.0) 0.98,0.323
24 56 (50.0) (48.7) 0.14, 0.987
21 (47.7)
14 (51.9)
Ovr
Ob
8 (30.8) 14 (15.6)
1 (3.8) 13 (14.4)
105 (89.7)
111 (94.9)
13 107 (10.8) (89.2) 2.62, 0.106
2 118 (1.7) (98.3) 3.02,0.048
20 100 (16.7) (83.3) 0.41,0.521
Un = underweight, Nm = Normal, Abn = Abnormal, Ovr = Overweight, Ob = Obese.
Table 3. Association of smoking status and cardiovascular risk factors among male youth Cardiovascular risk factors No. of cigarette smoking
Systolic blood pressure High Normal
Diastolic blood pressure High Normal
Glycemic status
Total cholesterol
HDL-C level
Body Mass Index
High
Abn
Low
Un
≤ 5 cigarettes per day (n = 26) ≥ 6 cigarettes per day (n = 92) X2 , p value
6 20 (23.1) (76.9) 6 86 (6.5) (96.7) *4.40, 0.036
3 23 (11.5) (88.5) 3 89 (3.3) (96.7) 1.42, 0.234
2 24 (7.7) (92.3) 5 87 (5.4) (94.6) 0.01,1.000
Normal
Normal
4 22 (15.4) (84.6) 12 80 (13.0) (87.0) 0.98, 0.323
Nm
14 12 (53.8) (46.2) 54 38 (58.4) (41.3) 0.01, 1.000
Nm
5 12 (19.2) (46.2) 19 44 (21.1) (48.9) 4.41,0.221
Un = underweight, Nm = Normal, Abn = Abnormal, Ovr = Overweight, Ob = Obese, * Yates corrections.
Table 4. Crude Odd Ratios and 95% confidence intervals for cardiovascular risk factors among male youth Cardiovascular risk factors p, 95% CI Smoking Yes No
Systolic hypertension 0.152 (0.266 - 1.230)
Diastolic hypertension 0.114 (0.163 - 1.213)
Diabetes mellitus
low HDL-C
Obesity
0.068 (0.900 - 20.811)
High Total cholesterol 0.522 (0.619 - 2.576)
0.323 (0.463 – 1.289)
0.764 (0.606 – 1.976)
0.57 1.0
0.45 1.0
4.33 1.0
1.26 1.0
0.77 1.0
1.10 1.0
Malaysian Journal of Public Health Medicine 2013, Vol. 13(1): 28-36 From table 4, although all the results were not significant, the crude odd ratio for smoking showed higher trend to become obese, diabetics and hypercholesterolemia. Whereas, the crude odd ratio for diastolic hypertension and low level of HDL-C had showed protective trend for those who smoke although the results was not significant. Majority of the male youth who smoked had at least 1 or more cardiovascular risk factors (refer Table 5). Table 5. Number of cardiovascular risk factors among smokers in male youth population Number of cardiovascular risk factors None 1 2 3 4 5 All 6
n (%) 29 (24.6) 47 (39.8) 22 (18.6) 19 (16.1) 1 (0.8) none none
DISCUSSION
Prevalence of current smoking, %
The increasing rate of the prevalence of NCD diseases and NCD risk factors in Malaysia is alarming. Focus on primary prevention and early identification of NCD risk factors are being emphasize especially among the younger age groups1. According to Global Youth Tobacco Survey (GYTS), changes in smoking behaviour in the young will affect mortality rates for several
decades13. Even though the full hazards of smoking take many decades to emerge, for those people who initiates smoking early in adolescence and continue throughout the middle age will affect the mortality rates and it is predicted that majority of the excess risk of death due to smoking in the middle and old age can be avoided by quitting before age 4014. The prevalence of smoking among male youth in this study was (46.6 %) comparable with two other recent studies on prevalence among male youth in Malaysia which was 46.7% and 41.2% with the same age groups15-16. Despite of all control and preventive measures taken by the government, such as ‘Stop Smoking’ campaign and enforcement of smoking laws, the prevalence still consistent and the trend of smoking among youth is alarming. The prevalence of smoker among Malay youth was higher than the non Malay (Figure 1) in this study. This prevalence was comparable with data from NHMS III for young adults who smoke are mostly Malay ethnic (10.9%) compared to others2. However, the lower smoking prevalence among non Malay should not promote complacency because this may not show the real situation since the participants in this study were majority from Malay ethnicity. A study among United States youths age 18-24 years of age also revealed that White American had higher prevalence of smoking (38.0%) compared to Mexican American and Black (5.7%)17.
50 45 40 35 30 25 20 15 10 5 0 19
20
21
22 Age,year
23
24
Figure 1. Prevalence of current smoking status among male youth age 19 -24 years
Malaysian Journal of Public Health Medicine 2013, Vol. 13(1): 28-36 Most of the smokers among the male youth in this study were having at least one or more cardiovascular risk factors (Table 5). These findings should provoke our health promotion team and also school health team to tackle this problem in order to prevent the acceleration of coronary heart disease in early adulthood. In a cross sectional study done among those healthy youth in Mexican, those youth who smoked had less favourable cardiometabolic risk profile than the non smoker18. In this study, a significant association between glycaemic status and smoking among male youth was revealed (p=0.048). Among those who smoked, 6.8 % of them had high blood glucose level compared to non smoker. However, there was no significant association for crude odd ratio between smoking and risk to develop diabetes mellitus compared to non smoking (OR: 4.33; 95% CI: 0.900-20.811) (p = 0.068). A study in United States shared the similar findings, among the youth who smoked, 27.0 % of them were having Type 1 Diabetes Mellitus and 37.3 percent of them was already develop type 2 Diabetes Mellitus19. Unfortunately, the data on youth in Malaysia for diabetic status is still in scarce. Smoking status and systolic blood pressure showed no significant association in this study, however, those who smoked 5 or less cigarettes per day was significantly associated with high systolic blood pressure (p=0.036). This result was contradict with the pathophysiology of smoking that showed smoking causes endothelial injury thus lead to vasoconstriction of the blood vessels and high cardiac output thus favours the development of hypertension21. A study done in Iran also revealed that prevalence of hypertension was higher among smoker than non smoker22. In study among youth in Canada clearly showed that those who smoke heavily (6 or more cigarettes per day) had higher mean of systolic blood pressure compared to those who smoked less20. In our study, the self administered data sheets was used and this may cause underreported data since most of the youth usually will not revealed that they are a smoker and the number they actually smoked especially when it was conducted in their house where their parents also present. In this study, there is a trend shown that the crude odd ratio for non smoker is about 2 times to get systolic hypertension (OR=1.75, CI: 0.8133.766) compared to smoker but the results was not significant. Interestingly, there were various studies since 1971 on the relation between
smoking and blood pressure but then they come into controversial results; some believe that smoking can increase blood pressure23, while some reported that blood pressure of smokers was lower than non smokers24. Recent study suggested that smoking cause vasomotor dysfunction as the result of reduction of nitrous oxide (NO) that responsible as a vasoregulatory molecule that would have hypotensive action24. Some study also postulated that the effects of chronic smoking with lower blood pressure was due to non nicotine substances in cigarette smoke which might affect on lowering blood pressure 23,24 . Nevertheless, the exact mechanism and pathophysiology of such effects in cigarette smoking are still not well understood. For obesity risk factor, in our study there was no significant association between smokers and risk to be obese than non smokers, however it showed higher risk trend in smoker (OR: 1.10; 95% CI: 0.606 – 1.976) (p = 0.764). Previous study also shown that smokers tend to indulge in unhealthy lifestyle such as lack of physical activity, poor fruit and vegetable consumption and increased in alcohol consumption thus lead to weight gain and obesity28. In one study by Nakamura25 those smokers who smoked more than 20 sticks per day had doubled risk to be obese compared to smoker that smoked less than 10 cigarettes per day. Similarly in our study, most of the smokers were overweight compared to non smokers and those who smoked 6 or more cigarette per day were more in overweight and obese compared with those who smoked less. For total cholesterol level, smoking had no significant association with the risks of developing higher cholesterol level compared to non smoker, although the crude odd ratio was higher for smokers (OR: 1.26; 95% CI: 0.619 – 2.576). This was inconsistent with the pathophysiology of smoking that it able to increase the LDL-C level, plasma triglycerides and VLDL level thus simultaneously lower the HDL-C level and proven by the Framingham study that showed cigarette smoking responsible for a drop of HDL-C level by 4mg/dl in men and 6 mg/dl in women26,27. Despite of this, there were several study among youth shown that there were not much increment of total cholesterol level and low HDL-C level among the youth since there were still short exposure of smoking28. The findings of this study will assist policy makers in strengthening NCD prevention among youth by providing evidence based data on pattern of smoking and most importantly the earliest age of
Malaysian Journal of Public Health Medicine 2013, Vol. 13(1): 28-36 smoking initiation among youth. By this data, policy makers can alert the regulator or legal enforcer to make amendment and strengthened the enforcement law regarding prohibition of smoking among youth. The prevention programme can be initiated earlier than previous since the smoking initiation age of male youth in Malaysia is as early as in primary school children. Although in the early stage to be significant establishment of diseases, the cardiovascular profile of the youth who smoke showed to be in the verge of normal range. They are the high risks group that can be “salvageable”. Youth is the most important phase which NCD risk behaviours develop and solidify and the longer they go unaddressed, the harder they are to change. The main limitation of this study is that important factors which may contribute to the cardiovascular risk factors among youth such as dietary habits, physical activity and genetics were not included. This study used a crosssectional design and thus, the temporal relationship between cigarette smoking and cardiovascular risk factors unable to be established. The usage of self reported health behaviours especially cigarette smoking status, number of cigarettes per day may have been under reported or the participants may deny their smoking behaviour. Another limitation of this study is that the data are from 2002 which is about 10 years ago and may not reflect the current smoking patterns among male youth. The measurement bias is explicitly in this study, the lipid profile and blood glucose were taken by rapid tests only and without the respondents being fasting at least 8 hours prior to the blood taking procedure. This may explained the non significant association between smoking and other cardiovascular risk factors such as total cholesterol and HDL-C level. Despite of the limitations, this study provides the prevalence of smoking among male youth which is worrying and need urgent actions and attentions. Smoking is an avoidable risk factor for the development of cardiovascular diseases. Since the escalation of cardiovascular risk factors enhanced by smoking, prevention of cigarette smoking in youth is the most essential.
baseline for further study, such as genetic factors among the youth that may be the strong predictive factor toward development of coronary heart diseases.
ACKNOWLEDGEMENT We gratefully acknowledge the Community Health Department of University Kebangsaan Malaysia for the health data and those who directly or indirectly involved in this study.
REFERENCES 1.
Ministry of Health Malaysia. National Strategic Plan for Non-Communicable Disease. Non Communicable Disease Section, Disease Control Division. First Edition, 2010.
2.
Palanisamy P, Govindaswamy B, Yagneswara R, Jawahar F. Cigarette smoking-effect of metabolic health risk: a review. Diabetes & Metabolic Syndrome: Clinical Research & Reviews 2009; 3(1): 120–7.
3.
Mahesar H, Mahesar SM, Khand FD, Khand A, Seehar GM. Effect of smoking on blood pressure of inhabitants of Hyderabad vicinity. Sindh University Respiratory Journal 2009; 41(3): 25-30.
4.
Ministry of Health Malaysia, Public Health Institute. The Third National Health and Morbidity Survey – Smoking, 2006.
5.
Beziaud F, Halimi JM, Lecomte P, Tichet J. Cigarette smoking and diabetes mellitus. Diabetes Metab 2004; 30 (2): 161–6.
6.
Lee J, Johnson C, Rice J, Warren CW, Chen T. Smoking beliefs and behavior among youth in South Korea, Taiwan, and Thailand. Int J Behav Med. 2012; 2(3): 115-28.
7.
International Union against Tuberculosis & Lung Disease Asia Pacific Region 1st Asia Pacific Regional Conference. Malaysian Smoking Cessation and Smoke Free Laws. Tobacco Control Unit & FCTC Secretariat Disease Control Division Ministry of Health Malaysia 2007. Available from: http://www.maptb.org.my/files/iuatld2007/ iuatld07presentations.htm (accessed 28 April 2012).
8.
Zarihah MZ. Adult smoking in Malaysia in the Third National Health and Morbidity Survey
CONCLUSION From this study, we can plan to target youth smoking as part of ongoing community – based intervention program especially in our health clinics. Furthermore, this study may act as a
Malaysian Journal of Public Health Medicine 2013, Vol. 13(1): 28-36 III Smoking. Kuala Lumpur: Ministry of Health Malaysia, 2007. 9.
Chaoyang L, Earl SF, Patrick E et al. Non– high-density lipoprotein cholesterol concentration is associated with the Metabolic Syndrome among US youth aged 12-19 Years. J Pediatr 2011; 15(8): 201-7.
10. World Health Organization/International Society of Hypertension Guidelines. Jour of Hypertensi 2007; 25(8): 1578-82. 11. NCEP Malaysia. NCEP Adult Treatment Panel III. National Cholesterol Education Program report, 2002. 12. WHO. Definition and diagnosis of diabetes mellitus and intermediate hyperglycemia. Report of a WHO/IDF Consultation, 2004. Geneva: World Health Organization, 2004. 13. Manimaran K. Global Youth Tobacco Survey (GYTS) Malaysia. Ministry of Health Malaysia Report, 2003. 14. Nyi Nyi N, Zulkifli A, Razlan M, Farique R, Haslan G, Mohd Hilmi AB. Factors Related to Smoking Habits of Male Adolescents. Tobacco Induced Diseases 2004; 2 (3): 133-40. 15. Redhwan A, Sami AR, Thekra HN, Robert C, Karim AJ. Prevalence of smoking and associated factors among Malaysian university students. Asian Pacific J Cancer Prev 2011; 12(1), 619-24. 16. Tawima S, Buppha S, Borland R, Maizurah O, Driezen P. Smoking behaviour among adolescents in Thailand and Malaysia. Southeast Asian J in Trop Med of Public Health 2011; 42(1): 218-24. 17. Marilyn AW, Thomas NR, Sundquist J, Helena CK. Ethnic variation in cardiovascular disease risk factors among children and young adults: findings from the Third National Health and Nutrition Examination Survey, 1988-1994. JAMA 1999; 28 (1): 1006-13. 18. Chiolero A, Wietlisbach V, Ruffieux C, Paccaud F, Cornuz J. Clustering of risk behaviors with cigarette consumption: a population-based survey. Prev Med 2006; 42(5): 348-53. 19. Kristi R, Angela DL, Anderson AM et al. Prevalence of tobacco use and association
between cardiometabolic risk factors and cigarette smoking in youth with type 1 or type 2 diabetes mellitus. The Journal of Pediatric 2011; 158 4): 594-601. 20. Ravi R, Anthony JG, Hanley, Phillip WC, Stewart BH, Bernard Z. Cigarette smoking and cardiovascular risks factors among aboriginal Canadian youths. CMAJ 2005; 173(8): 885-9. 21. Linsay G, Lee IM, Howard D, Sesso G, David B. Blood pressure in early adulthood, hypertension in middle age, and future cardiovascular disease mortality HAHS (Harvard Alumni Health Study). Journal of the American College of Cardiology 2011; 58 (23): 1233-6. 22. Abtahi F, Kianpour Z, Zibaeenezhad MJ et al. Correlation between cigarette smoking and blood pressure and pulse pressure among teachers residing in Shiraz, Southern Iran. Iran Cardiovascular Respiratory Journal 2011; 5(3): 97-102. 23. Magnus HF, Tom IL, Turid LH, Torstein V. Life style related to blood pressure and body weight in adolescence: Cross sectional data from the Young-HUNT study, Norway. BMC Public Health 2008; 8(7): 111-20. 24. John A. The pathophysiology of cigarette smoking and cardiovascular disease: an update. JACC 2004; 43(10): 1713-7. 25. Koshi N, Federica B, Lam TH, et al. Cigarette smoking, systolic blood pressure, and cardiovascular diseases in the Asia-Pacific region. Stroke 2008; 39(2):169-72. 26. Charles W, Nathan RJ, Armando P. Global Youth Tobacco Surveillance 2000—2007. Morbidity and Mortality Weekly Report 2008; 57(1): 1-21. 27. Garrison RJ, Kannel WB, Feinleib M, Castelli WP, McNamara PM, Padgett SJ. Cigarette smoking and HDL cholesterol: the Framingham Offspring Study. Atherosclerosis 1978; 30(5): 17-9. 28. Damiano B, Samuela C, Beatrice F et al. Effects of timing and extent of smoking, type of cigarettes, and concomitant risk factors on the association between smoking and subclinical atherosclerosis. Journal of the AHA 2009; 2(7): 18-23.
