Status of lipids and the frequency diseases of cardiovascular origin in smokers according to the length period of smoking and a number of cigarettes smoked daily

Cigarette smoking aff ects all phases of atherosclerosis from endothelial dysfunction to acute occlusive clinical events. Th e problem is, whether the length of the period of cigarette smoking has a more refl ection to the status of lipids and illnesses of cardiovascular system or the bigger number of smoked cigarettes in a shorter time-period? Th e observed sample has constituted of two groups of smokers, both gender, age  years old. Th e fi rst group consisted of  examinees divided in  subgroups according to a number of years they have been smoking. Th e second group consisted of  examinees, which was divided in  subgroups, according to average number of cigarettes smoked daily. Th e average values of serum cholesterol (. vs. .mmol/L), triglycerides (. vs. . mmol/L) and LDL-cholesterol (. vs. . mmol/L) were always higher in a group of smokers according to a number of daily smoked cigarettes. Average value of smoking consumption period was higher in a group of smokers according to the length of smoking consumption period than in a group of smokers according to a number of cigarettes smoked daily (. y vs. . y.). Hypertension ( vs. .), angina pectoris (. vs. .), CHD (. vs. .) and myocardial infarction ( vs. .) appeared much more in the group of smokers according to a number of cigarettes smoked daily. More refl ection to the status of lipids and illnesses of cardiovascular system has the bigger number of smoked cigarettes daily than the length of the period of cigarette smoking. ©  Association of Basic Medical Sciences of FBIH. All rights reserved


Introduction
Link between smoking and disturbance of lipid degradation has been found.It was also determined that smokers have higher levels of total cholesterol (TC), triglycerides (TG), atherogenic VLDL-C, low density lipoprotein cholesterol (LDL-C) with lower level of high density lipoprotein cholesterol (HDL-C), which normally does not happen in non-smokers [].High level of triglyceride combined with high level of LDL-C leads to acceleration atherosclerosis and increases the risk for heart attack and stroke [].Cigarette smoking has been shown to raise the level of LDL-C by as much as  [].Th e initial trigger for the development of atherosclerosis is probably damage to the endothelial cells layer lining the artery.Th is damage may be caused by smoking, viruses, chemicals and drugs.In the earliest stages, yellow fatty streaks developed in the blood vessels are caused by the deposition of fats in the wall of the artery.Th ey are yellow due to the deposited cholesterol.Fatty streaks will not cause any symptoms, but are the earliest sign of arterial disease and can progress to the development of atherosclerotic plaques.Plaques are caused by the accumulation of the LDL-C [].It is well known that increased level of serum cholesterol that is mainly consisted of LDL-C particles is the main risk factor for coronary disease and myocardial infarction, and it is also important risk factor for stroke.Th e importance of hypertriglyceridemia is that it is always followed by lower level of HDL-C which is a risk factor for development of atherosclerosis independently from the other factors [].The problem is whether the length of the period of cigarette smoking has a more reflection to the status of lipids and illnesses of cardiovascular system or the bigger number of smoked cigarettes daily in a shorter period?
Aim of the study: Are there any statistically signifi cant diff erences in average values of the total serum cholesterol, serum triglycerides as well as LDL-C and HDL-C between the two groups of smokers?(Group of smokers according to the number of years they have been smoking and group of smokers according to the average number of cigarettes daily smoked).Are there any statistically significant differences in the frequency of illnesses of cardiovascular system between the two groups of smokers?Does the length of smoking have a greater impact on frequency of illness from cardiovascular diseases than the number of cigarettes smoked daily?

Materials and Methods
The sample has constituted of  smokers, both gender, age - years old.The sample was divided in two groups of smokers; the first group consisted of  examinees with different period of length of smoking cigarettes and the second group consisted of  examinees that smoked a different number of cigarettes per day.In the group of smokers according to the length of smoking period there were much more male smokers in older subgroups vs. much more female smokers in younger subgroups (Table ).In the group of smokers according to average number of cigarettes smoked daily, there were much more "heavy smokers" in male subgroups vs. more "light smokers" in female subgroups (Table ).The investigation was prospective, randomized, clinically and controlled study, from Tuzla region.Each examinee was treated per anamnesis, physical examination (blood pressure); ECG and laboratory tests of total cholesterol, triglycerides, HDL-C and LDL -C.Inclusion criteria for the study: • Age from  to  years, both gender,

Statistical analysis
The data were expressed as mean ± SD.The statistical significance between the groups by variables from goals of study was evaluated by hi-square test and Student's t test, using Statistical Package for the Social Sciences (SPSS Cary, NC, USA), version .

Results
There was no statistically significant difference between the genders of examinees (Table ).Average value of smoking consumption period was higher in a group of examinees according to the length of smoking consumption period than in a group of examinees according to a number of cigarettes smoked daily.Certified with student t-test there was statistically significant difference between the groups (Table ).The average values of cholesterol in both groups of examinees were very high, especially in a group of smokers according to a number of cigarettes smoked daily.Certified with t-test there was statistically significant difference between the groups (Table ).
Th e average values of triglycerides in both groups of examinees were higher, the diff erences between examined groups were minimal, and certifi ed with student t-test there was no statistically signifi cant diff erence between the groups (Table ).
It is evident that the average value of LDL-C in both groups of smokers are higher than the predicted values, thus the average value of LDL-C in a group of smokers according to a number of cigarettes smoked daily is higher than the average value of LDL-C in a group of smokers according to the length of smoking period.Certified with t-test there was statistically significant difference in average values of LDL-C between the groups (Table ) In both groups of examinees the values of serum HDL-C were in predicted values, although the average value of serum HDL-C in the group of smokers according to a number of cigarettes smoked daily was lower compared to the average value of serum HDL-C of the group of smokers according to length of smoking period.Certifi ed with t-test there was a statistically signifi cant diff erence between the groups (Table ).High blood pressure, angina pectoris, myocardial infarction and chronic heart disease appeared much more in the group of smokers according to a number of cigarettes smoked daily than in the group according to duration of smoking period.Chi square test showed that there was statistically signifi cant diff erence between the groups (Table ).
As the most frequent ECG-changes in the both groups of ex- aminees were registered ischemic coronary disease, left ventricular hypertrophy, heart rhythms disturbance and myocardial infarction.Certifi ed with χ  test there was a statically signifi cant diff erence between the examined groups (Table ).
Existence of blood vessels diseases (vascular diseases) was registered in both groups of examinees; where of the most frequent was peripheral venous disease, followed by stroke which appeared almost equally in both groups of examinees.Certified with χ  -test there was no statistically significant difference between the groups (Table ).

Discussion
Results of this investigation showed extremely high number of smokers among men in both groups; in the group according to the number of years of smoking consumption period male were represented with ., vs.  in the group according to a number of average numbers of cigarettes smoked on a daily basis.Female were found with ., in the group according to smoking duration vs.  in the group according to a number of average of cigarettes smoked daily.According to the results of National Health Interview Survey [], . of US adults were current smokers.Current smoking was higher among men (.) than women (.).From -, the percentage of daily smokers who smoked > cigarettes per day (cpd), (heavy smokers) decreased steadily from . -..During the same period the percentage of daily smokers who smoked - cpd and - cpd increased, from . -. and from . -., respectively.According to the  National Survey on Drug Use and Health [] among daily smokers aged  or older, . of them smoked a pack a day or more.A descriptive study [] was conducted in a Government Hospital in the Sakarya city center in Turkey between June  and June  which aim was to investigate the relationship between the statuses of hospitalized children with diagnosis of respiratory tract diseases with cigarette use in the parents.In this study parental smoking was observed in . of fathers, and . of mothers and . both parents were smoking.It means, that at least one parent was a smoker in more than  of the families.Smoking rates at home were signifi cantly higher in the family in which father educational status was low.Also, smoking rate of parents in the families who defi ned themselves in bad economic situation and the status of children exposed to cigarette smoke at home was determined high and diff erences were statistically signifi cant.Indian Academy of Clinical Medicine presented a study [] which had evaluated lipid profi le in young smokers and compared it with non-smokers in the fasting state.There was signifi cant increase in levels of total cholesterol, LDL-C, VLDL-C, and triglycerides in the men, while there was significant fall in average level of HDL-C in smokers as compared to that in non-smokers.It was revealed that mean serum triglycerides (± . mg/dl), LDL-C (.±.mg/dl) (p<.).Mean serum triglycerides levels in smokers were signifi cantly high, (±.mg/dl) (p<.).Most of the smokers had been smoking for a mean duration of  years.An Indian study [] included subjects who smoked at least fi fteen cigarettes per day for - years.Aim was to determine the effect of cigarette smoking on changes in lipid profile, lipid peroxidation and antioxidant status in stable ischemic heart disease and acute myocardial infarction.Authors found that the levels of total cholesterol, triglycerides, LDL-C and VLDL-C were signifi cantly increased (p<.), while the HDL-C level was signifi cantly decreased in patients suff ering from myocardial infarction and ischemic heart disease compared with control subjects.A highly signifi cant increase (p<.) in serum cholesterol, triglycerides, LDL-C, VLDL-C and decrease in HDL-C level was noticed in smokers than in non-smokers in the myocardial infarction group.Chinese epidemiological survey [] mainly reported considerable prevalence of hypertension (about ), obesity (near ) and dyslipidemia (over ), in individuals of over  years of age belonging to minorities from the pasture area of Xinjiang.No significant differences between men and women were detected (. vs. .,χ  =., p=.).The prevalence of dyslipidemia was . in the whole study population.
In our study we also analyzed the mean values of total serum cholesterol and triglycerides only in smokers.The mean value of cholesterol in the group according to a number of smoked cigarettes was (.±.mmol/L), and in the group according to the length of smoking consumption period (.±.mmol/L), so that we found a statistically significant difference between examination groups (p<.).Middle values of triglycerides were higher in both groups of examinees, but there was no any statistical signifi cation.Also, middle values of LDL-C were higher in both groups of examinees, and we found statistically signifi cant diff erence between examination groups (  We also certified the average value of smoking consumption period, which was higher in a group of examinees according to the length of smoking consumption period than in a group of examinees according to a number of cigarettes smoked daily, and we found statistic signification between the groups (. vs. .yrs).In a descriptive hospital based one year study [], in Karachi on ninety patients with stroke, . had cerebral infarction and . had cerebral hemorrhage.Hypertension was the most common modifiable risk factor in , followed by smoking in ., diabetes in ., dyslipidemia in ., heart disease in . and alcoholism . of cases.
In this investigation there were  smokers enrolled, with the age of - years, both gender, and we found that . of examinees in the group according to the length of smoking consumption period vs. . of examinees in the group according to a number of smoked cigarettes had stroke.
In the group according to a number of smoked cigarettes the most cases of stroke were registered in the subgroups of smokers who smoked more than  cigarettes per day.Also, we found in the group by length of smoking duration period that the most cases of stroke were registered in the subgroup of smokers who smoked for .- years.

Conclusion
Th ere were higher average values of total cholesterol (. vs. .mmol/L), triglycerides (. vs. .mmol/L) and LDL-C (. vs. .mmol/L) in a group of smokers according to a number of smoked cigarettes daily.Th e average value of HDL-C was of predicted value, although lower value of HDL-C was registered in a group of smokers according to a number of smoked cigarettes.Highly statistically signifi cant diff erence was estimated in the values of total cholesterol, LDL-C and in HDL-C in the group of smokers according to a number of cigarettes smoked daily, than in the group of smokers according to the length of smoking period.Th e number of smokers who suff er from high blood pressure, angina pectoris, myocardial infarction and chronic heart disease is more often registered in the group of smokers according to a number of smoked cigarettes compared to a group of smokers according to the duration of smoking consumption.We were confi rmed the hypothesis that a bigger number of smoked cigarettes per day has more refl ection to the status of lipids, and a bigger impact on frequency of illness from cardiovascular diseases than the length of smoking years.

Declaration of interest
None to declare.

TABLE 3 .
Structure of groups of examinees by gender related to the length of smoking consumption period and the average number of cigarettes daily smoked

TABLE 1 .
Group by length of smoking consumption period.Structure of subgroups by gender and length of smoking consumption period

TABLE 2 .
Group according to the average number of cigarettes smoked daily.Structure of subgroups by gender and average number of cigarettes smoked daily

TABLE 4 .
Average values of smoking consumption period of examinees according to the length of smoking period and to a number of cigarettes smoked daily

TABLE 9 .
Existence of cardiovascular diseases in both groups of smokers

TABLE 5 .
Average values of serum cholesterol (mmol/L) in smokers according to the length of smoking period and according to a number of cigarettes smoked daily

TABLE 6 .
Average values of serum triglycerides (mmol/L) in smokers according to the length of smoking period and according to a number of cigarettes smoked daily.

TABLE 7 .
Average values of serum LDL-C (mmol/L) in smokers according to the length of smoking period and according to a number of cigarettes smoked daily

TABLE 8 .
Average values of serum HDL-C (mmol/L) in smokers according to the length of smoking period and according to a number of cigarettes smoked daily

TABLE 10 .
ECG changes at the smokers according to the length of smoking period and an average number of cigarettes smoked daily *LVH -Left Ventricular Hypertrophy; *RVH -Right Ventricular Hypertrophy .±.mmol/L vs. .±.mmol/L) (p<.).Compared with the values

TABLE 11 .
Existence of blood vessel diseases in smokers according to the length of smoking period and average number of cigarettes smoked daily *ICV-insult cerebrovascular; *PAD-peripheral arterial disease; *PVD-peripheral venous disease of the other studies those values were signifi cantly higher.In this study we have not found expected decrease of HDL-C values.In both groups of examinees the middle values of serum HDL-C were in predicted values, although the average value of serum HDL-C in the group of smokers according to a number of cigarettes smoked daily was lower and statistically signifi cant diff erence compared to the average value of serum HDL-C of the group of smokers according to the length of smoking period.In this study existence of cardiovascular diseases is more often registered in the group of smokers according to a number of smoked cigarettes daily than in the group of smokers according to the duration of smoking consumption period; hypertension ( vs. .),anginapectoris(. vs. .)twicemore,chronicheartdisease (. vs. .)andmyocardialinfarction(vs. .).The first observational study of risk factors for coronary heart disease which followed in  countries,  years, confirmed that number of smoked cigarettes elevated the risk of several cardiovascular diseases[].Daily cigarette smoking increased the risk of fatal stroke three and half times in Chinese population[].The researchers studied a representative sample of . men and . women,  years and older, from  provinces in mainland China.After adjusting for other stroke-related factors such as age and blood pressure, cigarette smoking was found to be a signifi cant predictor of stroke.Cigarette smoking accounted for . of strokes and . of stroke deaths in men vs. . of strokes and . of stroke deaths in women.Compared with never smokers, the risk of stroke increased  for those smoking - cigarettes per day and  for those smoking  and more cigarettes per day.