Prevalence of Cardiovascular Disease and Associated Risk Factors among Adult Population in the Gulf Region : A Systematic Review

Background. CVD is a principal cause of mortality and disability globally. Objective. To analyse the epidemiological data on CHD, strokes, and the associated risk factors among adult population in the Gulf countries. Methods. A systematic review of published articles between 1990 and 2014 was conducted. Results. The analysis included 62 relevant studies. The prevalence of CHD was reported to be 5.5% in Saudi Arabia. The annual incidence of strokes ranged from 27.6 to 57 per 100 000 in the Gulf countries with ischaemic stroke being themost common subtype and hypertension and diabetes being themost common risk factors among stroke and ACS patients. The prevalence of overweight and obesity ranged from 31.2% to 43.3% and 22% to 34.1% in males and from 28% to 34.3% and 26.1% to 44% in females, respectively. In males, the prevalence of hypertension and diabetes ranged from 26.0% to 50.7% and 9.3% to 46.8%, respectively; in females these ranged from 20.9% to 57.2% and 6% to 53.2%, respectively. The prevalence of inactivity was from 24.3% to 93.9% and 56.7% to 98.1% inmales and females, respectively. Relatively moremales (13.4% to 37.4%) than females (0.5% to 20.7%) were current smokers. Available data indicate poor dietary habits with high consumption of snacks, fatty foods, sugar, and fast food. Conclusion. Effective preventative strategies and education programs are crucial in the Gulf region to reduce the risk of CVD mortality and morbidity in the coming years.


Introduction
Cardiovascular disease (CVD) is now recognized as the leading cause of death and disability worldwide [1].The World Health Organization (WHO) estimated that in 2008, out of 17.3 million CVD deaths globally, heart attacks (myocardial infarction) and strokes were responsible for 7.3 and 6.2 million deaths, respectively [1].According to the INTER-HEART and INTERSTROKE studies, hypertension, diabetes, dyslipidaemia, obesity, smoking, physical activity, poor diet, and alcohol consumption are the most common risk factors for myocardial infarction (heart attack) and strokes worldwide [2,3].
The Gulf Cooperation Council (GCC) is cooperation between Saudi Arabia, Bahrain, Oman, Qatar, the United Arab Emirates, and Kuwait.In 1981, the GCC was created to encourage investment and to adopt free trade between member states.This agreement also contributed to several fields including: education, culture, tourism, social opportunities, and health among the GCC members.The discovery of oil and other natural resources such as gas in the GCC countries including Saudi Arabia led to rapid development and economic growth [4].Along with the rapid socioeconomic growth in the Gulf countries, there has been a change in lifestyle such as an increased consumption of poor quality foods and the adoption of a sedentary lifestyle [5], and as a consequence the rates of CVD and associated risk factors among the Gulf population have also increased; the rates sometimes exceed that of developed countries [5].Furthermore, the number of deaths resulting from ischemic heart disease and hypertensive heart disease in the Middle East and North Africa region (including the GCC countries) was 294/100,000 and 115/100,000 respectively.Also, the number of disability-adjusted life years (DALYs) resulting from ischemic and hypertensive heart disease is 3702/100,000 and 1389/100,000, respectively, in the same region [6].The WHO estimated the total number of noncommunicable diseases resulting in death in the GCC states in 2008.CVD was estimated to account almost half of the deaths in Oman and Kuwait, 49% and 46%, respectively.The rate of CVD deaths was also high in Saudi Arabia, the UAE, Bahrain, and Qatar 42%, 38%, 32%, and 23%, respectively [7].Although some systematic reviews on the prevalence of CVD and/or CVD risk factors in the Middle East region have been published [8,9], these reviews were limited to either CVD risk factors only [8], or specific gender [9].To our knowledge, this is the first systematic review that provides a comprehensive analysis on the prevalence of CHD, strokes, and associated risk factors in the Arabic Gulf countries.The aim of this paper was to review the epidemiology of CHD, strokes, and the related risk factors among the adult population in the GCC.

2.
1. Data Sources.An extensive literature search was conducted on the prevalence of CHD and incidence of strokes and the burden of associated risk factors to identify articles or reports published between 1990 and 2014 using Pro-Quest Public Health, MEDLINE, PubMed, Google Scholar, and World Health Organization (WHO) website.A manual search of reference lists of original studies was searched.In addition, checking the review articles, contacting authors, the official website of the Gulf Heart Association were also searched http://www.gulfheart.org/ and the section labelled "GHA studies" was specifically scanned.The search terms used were shown in Box 1.

Study Selection.
A total of 7800 articles were identified in initial search.The titles and abstracts of all articles of potential interest were reviewed for inclusion and exclusion of studies.The criteria for selected studies aimed to include studies that indicated the prevalence of CHD and/or stroke and/or at least one of the associated risk factors: diabetes, hypertension, obesity, dyslipidaemia, dietary habits, smoking, and physical activity.All the included studies were required to only include individuals over 18.The CHD and stroke studies were not restricted by sample size due to the limited numbers of these studies in the GCC countries.However, all the included studies that examined the burden of the risk factors were restricted with a sample size that exceeded 500 except for diet studies.All selected studies were required to relate to at least one of the GCC populations.Only studies published in English and where full manuscripts were included.Studies were published in abstract form and those on congenital heart disease or other CVDs were excluded.A total of 190 full-text papers were identified and further reviewed.Finally, 62 articles including two articles by contacting authors directly were included in this review.Figure 1 summarizes the selection process of the reviewed studies.stroke and/or associated risk factors, and the prevalence of CHD and/or stroke and/or associated risk factors.The quality of selected studies was assessed according to the Centre for Reviews and Dissemination guidelines [10].Since there are few papers that addressed the study questions, no studies were excluded for their qualities.The quality assessment checklist of the included studies in the systematic review is shown in the far-right column of Tables 1 and 2.

Data Synthesis.
A narrative synthesis was performed to identify the study questions.It included describing all the included papers, summarising the findings of the data extracted from each study, and exploring the relationships between the results of the different studies.

Results
Of the 62 articles that are reviewed in the present study, 13 were published in the 1990s, another 40 in the 2000s, and 9 in the last four years.Of the included studies, 4 reported data on CHD, 12 on stroke, and 46 on the prevalence of the associated risk factors.Further, of these 62 selected studies, 22 were carried out among Saudi, 8 in Bahraini, 10 in Kuwaiti, 5 in Omani, 6 in Qatari, and 8 in the UAE populations, and 3 were carried out in multiple GCC countries.Regarding the study design; 48 studies were cross-sectional, 7 were retrospective, and 7 were prospective observational studies.Seven studies looked at employees, 4 at university and college students, 8 at primary health care attendants, 14 at CHD and stroke patients, and 29 at the general population.The sample size in CHD and stroke studies ranged from 62 to 23,227 and in the burden of risk factors studies it ranged from 227 to 195,874.Response rates ranged from 59% to 99.8%.The summary of the included articles on CHD and strokes is shown in Table 1, whereas the summary of included articles on the burden of associated risk factors is shown in Table 2. 3.1.CHD and Strokes in the GCC Region.Overall, there is a lack of information on CHD and strokes in Arabic Gulf countries.The only nationally representative study conducted in Saudi Arabia reported the crude prevalence of CHD of 5.5% among the Saudi population [11].This survey reported a higher prevalence of CHD in males (6.6%) compared to females (4.4%) and in urban Saudis (6.2%) than rural Saudis (4.0%).Further, the prevalence of CHD increased with age from 3.9% in 30-39-year olds to 9.3% in the 60-70-year olds [11].
The Gulf Registry of Acute Coronary Events (Gulf RACE), a project of Gulf Heart Association aimed to describe the characteristics, in-hospital outcomes, and associated risk factors of the acute coronary syndrome patients (ACS) and recruited patients from 64 hospitals in Bahrain, Oman, Qatar, Kuwait, the UAE, and Yemen [12,13].The Gulf RACE study reported ACS was more prevalent in male (74%) than female (24%) patients [12].It also reported a high prevalence of diabetes (40%), hypertension (49%), dyslipidaemia (32%), smoking (38%), and obesity (27%) among ACS patients in the five Gulf countries [13].The highest rates of the risk factors were in Bahrain and Kuwait, except for smoking, which has the highest rates in the UAE and Kuwait [13].The prevalence of CVD risk factors was higher in females than males, including diabetes (55% versus 36%), hypertension (70% versus 43%), and dyslipidaemia (44% versus 28%), respectively [12].Significantly more males (47%) than females (5%) were current smokers [13].
Similarly, the Saudi Project for Assessment of Coronary Events (SPACE) registry reported the characteristics and prevalence of risk factors among ACS patients in Saudi Arabia [14].The SPACE registry reported that ACS was more frequent in males (77%) than females (23%) [14].Ischemic heart disease was present in 32% of the study population.The study also reported diabetes to be the most common risk factor for CHD (56%) followed by hypertension (48%), being a current smoker (39%), and hyperlipidaemia (31%) [14].
Five studies reported the incidence of stroke in Saudi Arabia, Kuwait, Qatar and Bahrain [15,17,19,20,25].The incidence of stroke ranged from 27.6 per 100 000 in Kuwait to 57 per 100 000 in Bahrain [15,17,19,20,25].Further, the most common type of stroke in the region was ischemic    ( * ) the quality assessment checklist assessed according to the Centre for Reviews and Dissemination guidelines (CRD) for nonrandomized studies: 1-Was the aim of the study stated clearly?2-Was the methodology stated?And was it appropriate?3-Were appropriate methods used for data collection and analysis?4-Was the data analysis sufficiently rigorous?5-Were preventive steps taken to minimize bias?6-Were limitations of the study discussed?7-In systematic review, was search strategy adequate and appropriate?

The Burden of the CHD and Stroke
Risk Factors in the GCC Region.The risk factors for CHD and stroke can be categorized into two groups: metabolic risk factors (obesity, hypertension, diabetes, and dyslipidaemia) and behavioural risk factors (diet, smoking, and physical activity).In this section, the burden of various risk factors among healthy population in the GCC states is described.

Overweight and Obesity.
Prevalence of overweight and obesity has been reported in 13 studies: 4 in Saudi Arabia [28,31,32,39], 2 in Bahrain [66,68], 2 in Kuwait [54,55], 2 in Oman [63,65], 1 in Qatar [60], and 2 in the UAE [43,46].Based on the available national representative studies, the prevalence of overweight in males and females in the GCC region ranged from 28.8% to 42.4% and from 27.3% to 32.7%, respectively, while the prevalence of obesity in males ranged from 10.5% to 39.2% and in females ranged from 18.2% to 53%.The prevalence of overweight and obesity increased with age with the highest level in the middle age groups (30-39 and 40-49 years) [28,31,32,39,43,46,54,55,60,63,65,66,68].The obesity rates in urban areas were higher than in rural areas [28,31,32,63].In general, the prevalence of overweight and obesity is remarkably high in the GCC states and Oman reported the lowest rates of obesity within the region.
The rate of hypertension in the GCC states ranged from 26% to 50.7% in males and from 20.9% to 31.7% in females [33,35,43,44,58,62,65,69]. Across all studies, the prevalence of hypertension considerably increased with age with the highest rates in the 45-65 age groups.The prevalence of hypertension in Saudi Arabia was lower than Oman, Bahrain, and Qatar but close to the UAE.The lower rate of hypertension in Saudi Arabia may not be true reflection of the situation as the reported study was relatively old [35].
The overall prevalence of diabetes ranged from 6% to 23.7% in the GCC.Three studies showed higher diabetes rates among females [31,59,67], while three studies indicated the opposite [29,45,56].Four studies showed almost no difference in the prevalence of diabetes between genders [43,51,62,65].The prevalence of diabetes rose proportionally with age and reached the highest rates in both sexes among those aged 55-64 years and over [29,31,43,45,51,56,59,62,65,67].It was also considerably higher among the urban population [29,62].Overall, the available data on the prevalence of diabetes in this region indicated that Saudi Arabia, Bahrain, and the UAE have the highest rates of diabetes compared to the other Gulf countries especially Kuwait, where the rates of diabetes were relatively lower; however this might be due to the underestimation of the actual prevalence in one Kuwaiti study as it excluded diabetic subjects on medication [56].
3.2.4.Dyslipidaemia.The prevalence of dyslipidaemia was reported in 7 studies: 3 in Saudi Arabia [27,31,37], 1 in Kuwait [53], 2 in Oman [62,65], and 1 in the UAE [43].There was no consistent definition of dyslipidaemia within the region.The majority of the dyslipidaemia studies reported the prevalence rate based on total cholesterol and triglycerides levels.
Overall, dyslipidaemia levels were higher in males than females and increased with age gradually up to the age group of 50-59 when it became stable in some studies and slightly declined in others.The prevalence of hypercholesterolemia (HC) ranged from 17% to 54.9% in males and from 9% to 53.2% in females [27,31,37,53,62,65].There was no difference in HC between urban and rural residents [37,62].However, one study in Saudi Arabia showed higher rates of hypertriglyceridemia in the urban population (43.2%) than rural population (34.1%) [37].Based on the available data on dyslipidaemia within the region, HC (≥5.2 mmol/L) was more prevalent in Saudi Arabia.The variation in definitions used in dyslipidaemia studies and the limited data in the GCC make it difficult to accurately compare between countries; however the levels of blood lipids appeared to be high in the Gulf region.[40][41][42] and UAE [48][49][50] have determined the eating habits among adult population in these countries.

Diet. Six studies carried out in Saudi Arabia
The dietary patterns presented in these studies are mainly characterized by a high consumption of snacks, fatty food, salty food, and sugar.A study in Saudi Arabia reported that more than half of the study population was consuming a high amount of snacks and fatty and salty foods in daily basis [41].Similarly, a high consumption of sugar and fast food was reported in the UAE [48,49].Further, a low consumption of fruits, vegetable, and cereals was reported in several studies [41,49,50].One study showed a high intake of fruits, vegetables, and dates [42].The findings from these surveys also demonstrated a high intake of total energy, fats, and protein [41,48].A Saudi survey showed a high proportion of total energy derived from fat and carbohydrates (38% versus 39%) and (46.1% versus 46.8%) in both males and females, respectively [41].Some of the popular unhealthy food habits reported were not having breakfast, consuming less than two meals per day, and a high consumption of fast food meals [41,49].A number of studies have examined the association between some food items and CVD risk factors [40,41,49].One study showed an inverse association between consumption of black tea and serum lipids [40], while another study reported a significant association of high intake of energy derived from fatty foods with BMI and hypertension in both genders [41].Further, low consumption of cereals and fruits was found to be associated with obesity [49].
The rates of cigarette smoking in the GCC ranged from 13.4% to 37.4% in males and from 0.5% to 20.7% in females.Furthermore, the prevalence of smoking fluctuated from age group to age group.It was more common in males at younger ages (18-25 years); however some studies reported a high prevalence in the older age group (40-59 years).In females, the highest rates of smoking were in the older age group (40-49 years) [30,43,52,57,61,71].One study in Saudi Arabia reported higher rates of cigarette smoking in urban than rural subjects [38].Overall, the prevalence of smoking was higher in Saudi Arabia, Kuwait, the UAE, and Bahrain in comparison to Oman.
The prevalence of inactivity was found to be significantly higher among the younger population in the region, and across all age groups physical inactivity was higher in females than males.The rates of inactivity ranged from 24.3% to 93.9% in males and from 50% to 98.1% in females in the GCC [36,47,60,64,66].In general, the rates of physical inactivity were considerably high in the GCC region especially Saudi Arabia.

Discussion
This review revealed that, in the GCC region, there is a lack of information on the prevalence of CHD with only exception in Saudi Arabia where one national survey reported 5.5% prevalence of CHD [11], which is lower than the prevalence rate reported in Egypt 8.3% [73], while it is higher than in India (3%), China (2%), and Europe (5%) [74,75].However, it is important to note that the Saudi report is relatively old and may not reflect the current situation.The rates of ACS and associated risk factors appeared to be very similar in Saudi Arabia (SPACE report) and other Gulf states (Gulf RACE report) except for diabetes, which is more prevalent in Saudi Arabia.However, the SPACE registry results came from phase 1 (pilot study) and thus based on smaller sample size compared to that of Gulf RACE [13,14].
In contrast to other ACS registries around the world, the prevalence rates of diabetes and current smoking are higher in the Gulf region, while a higher prevalence of hypertension and dyslipidaemia is observed in the Euro heart of the acute coronary syndrome survey and Canadian ACS registry [13,14,76,77].The rates of diabetes are ranged from 23.3% to 25.1% in the Euro heart survey, Canadian ACS registry, and the Global Registry of Acute Cardiac Events (GRACE) [76,77], while the prevalence of diabetes is much higher among the ACS patients in the Gulf States especially in Saudi Arabia (56%) [13,14].One possible explanation for this high rate of diabetes could be due the high prevalence of obesity and physical inactivity in the GCC region, especially in Saudi Arabia.Furthermore, the mean age of presentation in the SPACE and Gulf RACE cohort is about ten years younger than that reported in the Euro heart survey and the GRACE cohort [13,14,78,79].This might be due to the high rates of uncontrolled risk factors in the Gulf region as well as the high percentage of younger populations in these countries.
The crude annual incidence of stroke in the Gulf countries was generally lower than the reported incidence in some Arabic countries, for example, Libya (63/100,000) [80] and Northern Palestine (51.4/100,000) [81].The incidence is even much lower than that which is observed in some of the developed countries such as Scotland (280/100,000) [82] and the East Coast of Australia (206/100,000) [83].The low rates of strokes in the GCC countries could be explained by the relatively younger age of patients in these countries.Further, the majority of stroke studies in the region had no record on the number of patients who died before reaching hospital, thus underestimating the actual incidence rate.
Several studies in the Gulf States have reported a high incidence of stroke at a younger age.Of the stroke patients, 9.8% to 25% were less than 45 years old [17,23,25].The higher proportion of undiagnosed hypertension and diabetes might be a reason for younger stroke patients.One study in Saudi Arabia showed that only half of the hypertensive stroke patients were actually on medication [17].Further, lack of awareness about stroke in the Gulf countries might have led to an increase in the incidence of strokes as well as the rates of associated risk factors [84].
When looking at the burden of risk factors among healthy subjects in the GCC region, the prevalence of obesity in adult females is one of the highest amongst females worldwide.This review found that almost half of the females in Kuwait and Bahrain and around 35% of females in Saudi Arabia, the UAE, and Qatar were obese.The overall prevalence of overweight and obesity in the GCC is higher than that which was reported in other Middle Eastern countries such as Lebanon and Turkey [85,86].The prevalence was even higher than in many developed countries such as the USA and in developing countries such as India [87,88].The food customs in the Gulf region, such as weddings and religious events, might be an important contributory factor for such a high rate of obesity as they serve food that is rich in fat, usually "Kabsa, " which includes meat (from sheep or small camel) with rice.Even socialising with friends and family is usually around eating meals and snacks.
Likewise, more than half of the GCC population are physically inactive, with only a small proportion of people being active on a regular basis.Furthermore, the rate of inactivity appeared to be remarkably higher in Saudi Arabia than in other Gulf countries.The reviewed studies also indicated that males are more likely to be physically active than females, a finding similar to that was reported in Turkey and Pakistan [47].The unique social, cultural, and environmental factors of the GCC states, such as hot climate, lack of outdoor facilities, the limited number of health clubs, high cost of attending such clubs especially for females, high level of employment of domestic helpers, and the high dependency on automobiles are blamed on the increased levels of physical inactivity in both genders but more noticeably in females.Also, females have more social barriers that make it difficult for them to exercise outside the home without a family member [5,89].
In the Gulf region, males start smoking cigarettes at an early age (before 18 years), while females generally start after 30s.Cigarette smoking by younger and unmarried females is viewed as culturally unacceptable and can potentially destroy their reputation.However, the case is different when smoking sheesha (water-pipe) as Arabic societies in general accept sheesha smoking by females irrespective of their age and/or social status.
Hypertension and diabetes are the two major risk factors associated with CHD and stroke patients in all studies in the Gulf region; this might be related to the high rates of undiagnosed hypertensive and diabetic patients within the region.In Saudi Arabia, about 70% of the hypertensive people were unaware of their disease [35].A similar situation was reported in Oman, the UAE, and Bahrain [44,65,69].Likewise, a large number of diabetic subjects in Saudi Arabia (28%) and the UAE (41%) were unaware of their disease [29,45].The high rates of uncontrolled diseases such as hypertension and diabetes could be a reason for the relatively young age of CHD and stroke patients in the Gulf region.
The prevalence of dyslipidaemia in general is high in the GCC countries.The available national surveys indicated that half the Saudi population have high level of total cholesterol and almost half of the males and one-third of Saudi females have high level of hypertriglyceridemia [37].The rates of HC in Saudi Arabia are similar to that reported in USA (53.2%) [90].Dyslipidaemia is a major risk factor for CHD and plays a central role in the development of atherosclerosis.The high rates of dyslipidaemia in the GCC countries may be due to the high prevalence of physical inactivity, obesity, and diabetes among the Gulf populations.Also, as mentioned before, food customs and the consumption of high fatty foods might be contributing factors.
This review has a number of limitations.First, there was a lack of recent nationally representative reports in the GCC countries, and thus it is difficult to compare the data between GCC countries.Second, there was significant heterogeneity between studies with respect to definitions of the risk factors, design, and population characteristics.Third, only a few studies reported stroke incidence and the majority of them were hospital-based studies with an absence of data on Oman and the UAE.Fourth, there were only a few studies focusing on hypertension, dyslipidaemia, and physical activity.Moreover, the number of included studies relating to the prevalence of risk factors in Qatar and Bahrain were also relatively low.However, the strength of this review was that the literature search was conducted on multiple databases including personal contact of the authors to capture all relevant documents.

Conclusion
The present review revealed lower incidence of strokes in the GCC countries than in developed countries and that those affected were younger than in some developing and developed countries.Although there was lack of nationally representative data on the prevalence of CHD in the region, high prevalence of key risk factors was observed.Further, the patterns of risk factors were very similar between the Gulf countries; this may be due to the similarity in culture, religion, cuisine, lifestyle, and environmental factors between these countries.With the rapid urbanization in the Gulf region and the relatively young population, the prevalence of CHD and strokes is expected to increase in the next few decades, which in turn will raise the rate of CVD mortality and morbidity in the region.Well-designed populationbased nationally representative surveys focusing on CVD and its associated risk factors are crucial in the Gulf States.Furthermore, there is a need to increase the awareness of the high prevalence of CVD and associated risk factors among the public along with education programs on nutrition and healthier lifestyles including increase in physical activity levels in both men and women.In addition, there is also a need for preventative strategies, especially for type 2 diabetes, to be used in the region and the cooperation in management strategies, especially in obesity and diabetes is also crucial across the region.Moreover, addressing some of the cultural and social barriers that were mentioned previously is also important for reducing the risk of CVD and related risk factors among the GCC population.

Table 1 :
The characteristics and the main outcomes of the included studies on CHD and strokes in the GCC region.
M, male; F, female; U, urban; R, rural; DM, diabetes; IFG, impaired fasting glucose; HC, hypercholesterolemia; TG, triglyceride; TC, total cholesterol; HDL, high-density lipoprotein; LDL, low-density lipoprotein; HTN, hypertension; SBP, systolic blood pressure; DBP, diastolic blood pressure; NR, not reported; ACS, acute coronary syndrome; BMI, body mass index; Y, yes; N, no; and NA, not applicable.( * ) the quality assessment checklist assessed according to the Centre for Reviews and Dissemination guidelines (CRD) for nonrandomized studies: 1-Was the aim of the study stated clearly?2-Was the methodology stated?And was it appropriate?3-Were appropriate methods used for data collection and analysis?4-Was the data analysis sufficiently rigorous?5-Were preventive steps taken to minimize bias?6-Were limitations of the study discussed?7-In systematic review, was search strategy adequate and appropriate?

Table 2 :
Characteristics and prevalence data of the included studies on the burden of CVD risk factors in the GCC region.