Abstract: Background and Objective: Khat has severe adverse socio-economic consequences. It causes serious cardiovascular, neurological and psychiatric problems. The study aimed to evaluate the effect of chewing khat on intima-media thickness (IMT) of the common carotid arteries. Materials and Methods: This was a descriptive case-control cross-sectional study. A total of 50 participants of chronic regular khat chewers were investigated. B-mode ultrasound 7-10 MHz linear transducers used for assessment of common carotid arteries according to the standard carotid sonography protocol. The IMT was measured and the presence of plaques was assessed. Results: The carotid IMT was significantly increased in regular khat chewers more than the controls (p-value = 0.016). The common carotid IMT increased in smokers more than non-smokers among khat chewers (0.6710±0.20687 vs. 0.5789±0.16859 mm). Significant correlations existed between the duration of chewing khat and age with the presence of plaque (p-values = 0.013 and 0.002, respectively). Conclusion: There is a significant correlation between carotid plaque and longtime khat chewing. Khat is a contributory factor for increasing carotid intima-media thickness and formation of carotid plaques. A combination of khat and smoking produce more thickening of carotid intima-media.
INTRODUCTION
Khat (Catha edulis) is referred to the leaves of the Catha edulis plant which is an evergreen shrub that can grow to a tree size1. Figure 1 showed the khat tree. Chewing khat is a widespread social habit in Yemen, Somalia, Ethiopia and many other East African communities. It reported that khat-chewing in most of these countries had reached serious epidemic proportions2. It has been established that the khat leaves contain an active substance known as cathinone that has a stimulant effect on the central nervous system (CNS) like amphetamine3. Several studies reported that khat chewing was significantly associated with ischemic heart disease and stroke4.
Khat-chewing has been studied to increase the prevalence of acute cerebral infarction5. This is probably due to the substantially higher blood pressure among the khat-chewer peoples in comparison with the non-chewers4,6. However, there is a lack of definitive studies demonstrated a causal relationship between khat chewing and cerebrovascular accidents. For these reasons, the CCA is vital to be assessed as a part of the cardiovascular system (CVS) which influenced by cathinone and cathine which are responsible for their effects on the CNS and CVS4.
Ultrasonography is an ideal and reliable imaging modality for studying changes in the carotid artery morphology and sub-clinical atherosclerosis. Carotid intima-media thickness (CIMT) is significantly increased in patients with plaque and represents a marker of organ damage7. It was reported that, there was an association between CIMT and established risk factors8.
| Fig. 1: | Khat tree |
Furthermore, the effect of khat on IMT of the CCAs is not yet determined. Now-a-days, khat plants are considered as a severe health and biological problem. Khat agriculture consumes an excessive amount of water because of other economic useful crops.
The study aimed to explore the impact of chewing khat on intima-media thickness (IMT) of the CCAs. To date, few articles demonstrated the effect of khat use on CIMT among khat chewers.
MATERIALS AND METHODS
The design of the study was a case-control descriptive survey to deal with the effect of khat (Catha edulis) on IMT of the CCAs. The study was conducted at Kaah Community Hospital in Hargeisa, Somaliland, during the time from August-December, 2017. The participants consisted of 50 subjects, who are regularly chewing khat and categorized into two groups; 31 were khat chewers and smokers and 19 were periodically khat chewers without smoking. They were selected using simple and convenient systematic sampling. Exactly 48 of them were men and only two were women. Chewer’s age ranged from 20-64 years old. Structured data collection sheet was used to collect the demographic data and clinical history of the participants, status of chewing khat, the number of years they have been chewing khat and other habits that may affect the carotid artery like smoking. Participants with diabetes, cardiac and renal diseases were excluded from the study to maintain the effect of smoking among khat chewers. The participants were divided into groups; smokers and non-smokers and compared together to study the IMT changes.
All examinations were performed using a DCN3 Mindray ultrasound machine with linear multi-frequency transducer. The B-mode settings were adjusted to optimize the quality of the gray-scale images and the pulse repetition frequency (PRF).
Sonographic procedure for assessment of carotid-IMT: The IMT of both CCAs was examined using B-mode ultrasonography. The subject was lying on a comfortable examination table in a supine position with a small pillow under his head. The subject’s head was turned slightly away from the side to be examined. Both the right and left common carotid arteries were scanned with gray-scale to evaluate the CCA for their intima-media thickness (IMT) and to determine the presence or absence of atherosclerotic plaque.
A carotid artery plaque was defined as a localized protrusion of the vessel wall, which extended into the lumen >1.5 mm or had a thickness exceeding the intima-media thickness (IMT) of the adjacent portion of the vessel wall by >50%. The characteristics of the plaques were described following the modified classification and plaque morphology was defined regarding its echogenicity9.
Statistical analysis: The SPSS 16.0 (IBM, Cary, north Carolina) was used to analyze the findings. Independent student t-test was used to calculate the statistical values for comparison between khat chewers and non-khat chewers and to compare between controls and study groups for identifying IMT changes. Pearson correlation was used to find a correlation of duration of chewing khat and age with the presence of plaque. The p<0.05 were regarded as significant.
RESULTS
Out of the 50 individuals examined in this study, 48 (96%) participants were male and only 2 (4%) were female. Table 1 summarizes the characteristics of the participants; a total of 31 (62%) were khat chewers with smoking and 19 (38%) were khat chewers without smoking.
| Table 1: | Characteristics of participants and the presence of plaque among the khat chewers |
The mean age was 39.7±12 years and the duration of khat chewing was 14.74±8 years as summarized in Table 2. Data in Table 3 summarized the comparison of carotid IMT (CIMT) in control and regular khat chewers. The IMT increase of the right CCA was more significant among khat chewers than in control (0.6360 vs. 0.544 mm, p-value = 0.016). The increase of IMT of left CCAs was not significant (0.642 vs. 0.606 mm, p = 0.07). The results in Table 4 revealed the insignificant relationship in IMT of CCAs in khat chewers with smoking and khat chewers without smoking (p = 0.109 and 0.111, respectively). A significant correlation found between the duration of chewing khat and age with the presence of plaque (p = 0.013 and 0.002, respectively) as shown in Table 5.
DISCUSSION
The CIMT is an independent predictor of cardiovascular and cerebrovascular events. Several studies reported that associations existed between CIMT and established risk factors. However, in the existing literature, the current concepts of the risk factors of CIMT are not unified10. It was reported that the risk factors of CIMT included smoking, age, sex, alcohol consumption, blood pressure (BP), blood fat, blood sugar and lifestyle habits10.
| Table 2: | Distribution of duration of chewing khat |
| Table 3: | Comparison of carotid-IMT in control and regular khat chewers |
| *p<0.05 is significant | |
| Table 4: | Comparison of carotid-IMT of regular khat chewers with smoking and non-smoking |
| p<0.05 is significant | |
| Table 5: | Correlation of the presence of plaque with age and duration of khat chewers |
| *Correlation is significant at 0.01 level (2-tailed). *p<0.05 are significant | |
In the present study, it was observed that the IMT of the CCAs was significantly increased in khat chewers more than the control, significantly the IMT of the right CCA. This finding agreed with a previous study which demonstrated the immediate effect of khat on hemodynamics of CCAs and reported that the CIMT was significantly increased after chewing khat11. Despite this agreement with the previously cited study, this study demonstrated the impact of khat for an extended period while the other one studied the immediate effect of chewing khat for hours (before and after chewing). However; all previous studies have not included khat as a risk factor for CIMT. There were a lack of studies which demonstrated the effect of khat on CIMT. The present study revealed that the IMT of right and left CCAs increased in smokers more than non-smokers among khat chewers. The effect of smoking on CIMT was much demonstrated in the literature12-16. It was observed that the combination of khat chewing and smoking produced more increase in thickening of CIMT among khat chewers. However, no ever studies were demonstrated the impact of khat on CIMT.
In the current study, it was found that duration of chewing khat has a significant influence on the formation of the atherosclerotic plaque in the carotid artery in addition to the other habits like smoking which is usually used along with khat. The study showed that there was a statistically significant association between chewing khat and the presence of carotid plaques (p = 0.013). This suggested that as the duration of chewing khat increases, the risk of plaque formation will also increase. A previous study found a significant increase in CIMT among participants who chewed khat for few hours11. An available previous study in Yemen reported that khat chewing was an independent risk factor for stroke and in-hospital mortality17. Another study in India suggested that khat chewing was a strong contender as the cause of stroke18.
In this study, the results revealed a lousier effect of khat on CIMT when combined with smoking. This result is consistent with a previous study which reported that concurrent use of khat and tobacco was associated with increased adverse effect19.
In addition, studies assessed the effect of khat on cardiovascular are scarce, most of the available studies reported an adverse impact of khat on the cardiovascular outcome. Recent reviews in Yemen stated the presence of an association of khat with acute myocardial infarction and heart failure20. All of the mentioned studies have not demonstrated the effect of khat on CIMT as smoking did. In this study, khat is suggested to be a significant risk factor for carotid atherosclerosis. Identifying khat with increased CIMT will be helpful for the prevention and treatment of early atherosclerosis.
It was a single-center study and the sample size was not large enough and no similar study is available, secondly, it was difficult to find a khat chewer without smoking since the majority of chewers were smokers. Large samples are recommended for further studies to confirm the initial results of this study.
CONCLUSION
There is a significant correlation between carotid plaque and longtime khat chewing. Khat is a contributory factor for increasing carotid intima-media thickness and formation of carotid plaques. It is suggested to be a contributory factor of formation atherosclerosis.
SIGNIFICANCE STATEMENT
This study discovered the chewing of khat produced a considerable effect on carotid IMT that can be beneficial for the community to avoid the potential risks of regular khat use. This study will help the researchers to study suspected neurovascular changes leading to stroke that must be considered in future researches.
ACKNOWLEDGMENTS
I would like to thank the Department of Radiology in Hargeisa hospital in Somaliland, who helped us to perform the study and Dr. Abdalasamad Mohammed Salih (Radiology Department, Faculty of Radiological Sciences and Medical Imaging in Alzaiem Alazhari University, Sudan) for the valuable suggestions and correction of the manuscript.