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Vol. 11(2), pp. 159-171, 2021
ISSN: 2276-7797
Copyright ©2021, the copyright of this article is retained by the author(s)
https://gjournals.org/GJMS
The Prevalence of Dyslipidemia in the Niger Delta Region of Southern Nigeria
Daka, I.R.1*; Amaewhule, M.N.2; Wekhe C.3
1Department of Pharmacology, Rivers State University, Port Harcourt, Nigeria.
2Department of Internal Medicine, Rivers State University, Port Harcourt, Nigeria.
3Department of Radiology, Rivers State University, Port Harcourt, Nigeria
Type: Research
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Method: A cross-sectional study carried out among 107 participants ( 80 females and 27 males) aged between 23 and 80 years. They were first administered a structured questionnaire to obtain their socio-demographic data and lifestyle characteristics after which anthropometric assessment was performed. Thereafter, their blood pressure was taken and blood samples collected for blood sugar and lipid analysis.
Results: The prevalence of the various components of metabolic syndrome was also accessed and 18 (16.8%) had reduced high density lipoprotein cholesterol, 6 (5.6%) had raised triglyceride.It was found that 70 (65.4%) of the respondents had high blood pressure, 54 (50.5%) had raised blood sugar, 48(44.9%) had abdominal obesity, 31(29.0%) had central obesity. Dyslipidemia was highly prevalent in this geopolitical zone of Nigeria with the consistent pattern being low HDL-Cholesterol and high LDL-C.
Conclusion: Dyslipidemia is highly prevalent in Southern Nigeria and health education to increase awareness of the need for and to actually screen for dyslipidemia will facilitate early detection and treatment.
Published: 04/11/2021
Daka, I.R.
E-mail: iyaeneomidaka@ gmail.com
INTRODUCTION
Hyperlipidemia is a condition that incorporates various genetic and acquired disorders that describe elevated lipid levels within the human body. Hyperlipidemia is extremely common, especially in the Western hemisphere, but also throughout the world. Alternatively, a more objective definition describes hyperlipidemia as low-density lipoprotein (LDL), total cholesterol, triglyceride levels, or lipoprotein levels greater than the 90th percentile in comparison to the general population, or an HDL level less than the 10th percentile when compared to the general population. Lipids typically include cholesterol levels, lipoproteins, chylomicrons, VLDL, LDL, apolipoproteins, and HDL.
Dyslipidemia is a state that arises as a result of abnormalities in the plasma lipids. These abnormalities could be quantitative, qualitative or both. Quantitatively, dyslipidemia is due to elevated plasma total cholesterol (TC), elevated low-density lipoprotein cholesterol (LDL-C), elevated triglycerides (TG) and reduced high-density lipoprotein cholesterol (HDL-C) levels, occurring singly or in combinations. Qualitatively, dyslipidemia implies changes in composition of LDL-C which includes small dense LDL-C, increased TG content or increased electronegativity of LDL-C.
A linear relationship probably exists between lipid levels and cardiovascular risk. Dyslipidemia contributes to the development of atherosclerosis. The atherogenic dyslipidaemic profile is characterized by elevated TG, low HDL-C and a preponderance of small, dense LDL-C particles. This profile is typically associated with the metabolic syndrome and type 2 diabetes mellitus. [1]
The TC, TG, and HDL-C can be assayed while LDL-C is usually calculated. LDL-C constitutes about 60-70% of total serum cholesterol. [2]
There are no rigid numeric definitions of dyslipidemia. [3]
Standardized definitions for dyslipidemia
National Cholesterol Education Program/Adult Treatment Panel III (NCEP/ATP III) Definition [4] : The Third Report of the Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in adults, which is one of the most current and most frequently referenced diagnostic criteria for dyslipidemia, defines dyslipidemia as follows:
It further classified the risk associated with various lipid levels as follows:
Earlier studies from Nigeria reported that dyslipidemia was rare amongst Nigerians. Onyemelukwe and Stafford in 1981 suggested that protective cholesterol (HDL-C) was significantly higher in tropical Africa, [18] while Kesterloot et al. in Benin, South South Nigeria in 1989 showed that blacks had a low prevalence of dyslipidemia. [19]
This review of 13s recent studies showed that dyslipidemia is highly prevalent in Nigeria. All the studies except two defined their subjects using the ATP III criteria. The two other studies used the WHO criteria and the European Atherosclerosis Society criteria respectively.
Apparently healthy Nigerian adults
The elderly
Diabetic subjects
Hypertensive subjects
Diabetic hypertensive
Impact of dyslipidemia
Dyslipidemia is a common disorder but most patients are not diagnosed and therefore not treated. [7] The burden of the condition is very high in terms of morbidity, mortality, and medical costs. Dyslipidemia is the second most prevalent cardiovascular risk factor. [8] Hypertriglyceridemia when associated with high LDL-C significantly increases the risk of coronary heart disease (CHD). [9] WHO estimates in 2002 [10] showed that dyslipidemia accounted for 18% of ischemic heart disease, 56% of stroke, and more than 4 million deaths per year globally. Dyslipidemia together with CHD are leading causes of death for both men and women of all races and ethnicities in the United States of America. [11] Epidemiologic data show a continuous graded relationship between the total plasma cholesterol concentration and coronary risk, especially for younger men below the age of 40 years. [12] The age-standardized and sex-standardized mortality ratios in patients with hypercholesterolemia are 4-5 times higher than those in the general population. [13] A decline in plasma TC has significant impact on the morbidity and mortality rate from heart diseases, especially in patients at higher risk. [14] Longitudinal studies have demonstrated that reducing plasma TC by 1% decreases CHD mortality by 2-3%. [15]
Meta-analysis of 38 primary and secondary prevention trials also demonstrated that for every 10% reduction in plasma TC, CHD mortality is reduced by 15% and total mortality risk by 11%. [16] Incidence of dyslipidemia is highest in patients with premature coronary artery disease (defined as coronary artery disease occurring before 55-60 years of age in men and before 65 years of age in women). In this group of individuals, prevalence of dyslipidemia is as high as 75-85%, compared to approximately 40-48% in age-matched controls without CAD. [17]
In Nigeria, few studies have been done to describe the prevalence, pattern, and distribution of dyslipidemia in various parts of the country. This study seeks to describe the prevalence of dyslipidemia in the Niger Delta region of Southern Nigeria.
METHODOLOGY
This is a cross-sectional, descriptive, community-based study is to be carried out using a total of 107 adults; in Amadi-ama and Fimie communities in Port-Harcourt City Local Government Area of Rivers state, in Southern Nigeria. Approval for this study was obtained from the Ethics Committee of the Rivers State Ministry of Health, Port-Harcourt.
The participants were all apparently healthy adults aged between 20-80 years and were chosen via convenience sampling.The communities were initially sensitized about this study via town criers and church announcements and those that met the inclusion criteria were told to meet in the to meet in church halls for screening. All the individuals who gave their consent were included in the study. Pregnant and lactating women as well as those who are obviously ill or wheel-chair bound were excluded from the study. Strict Covid-19 prevention protocols were adhered to.
A screenng questionnaire, was given to participants and no monetary or any form of inducement was required of them.
The requirements for participation include being >18yearsof age with no previous history of hypertension or diabetes.
Anthropometric evaluation- Well trained examiners measured the anthropometric indices and participants were required to wear light, thin clothing and no shoes.
The indices are: a) BMI (Body mass index is body weight/square of height, and the unit is kg/metre square.
b) Blood pressure
c) Blood sugar
d) Lipid profile
The body weight was measured using an analogue medical scale while the height was measured with a standard stadiometer. They were measured to the nearest 0.1kg and 0.1cm respectively.
The classes of BMI reported by WHO are ;
18.5-24.9kg/m2-normal
25.0-29.9kg/m2-overweight
>30kg/m2–obesity
Classes of obesity include: class I -30-34kg/m2
class II- 35-39.9kg/m2
class III- >40Kg/m2
Blood pressure was measured with a clinically validated electronic sphygmomanometer – OMRON digital fully automated blood pressure monitor. Values were obtained after resting for 5mins in a seated position, with 30 seconds interval between cuff inflation.
An average of 3 measurements were taken, and care was taken to select the cuff size according to the participant’s arm circumference.
Assessments were performed in a dedicated room, with optimum temperature and lightning while respecting privacy.
Blood pressure values were categorised as follows:
(1) Normal: <120/80mm/hg
(2) Pre-hypertension: 120-139/80-89mm/hg
(3) Stage 1: 140-159/90-99mm/hg
(4) Stage 2: >The classes of BMI reported by WHO are ;
(4) Stage 2: >> 160/100mm/hg
Blood measurements- Blood sugar was assessed using a glucometer and strip, after the participant’s thumb is pricked in order to get a drop of blood on the strip. While the lipid level was obtained using a 5ml syringe and needle to collect at least 5mls of venous blood into a heparin containing bottle and samples sent to the chemical pathology laboratory for analysis.
The European Atherosclerosis Society [5]: This society defined dyslipidemia as the presence of any of the following:
World Health Organization (WHO) [6] : The WHO defined dyslipidemia as the presence of any of the following:
Some form of education on life style modification was also given to the participants accordingly. Data were analysed using the IBM SPSS Version 23.0.
RESULTS
Socio-demographics
A total of 107 respondents between the ages of 23 and 80 years were screened for Dyslipidemia( a metabolic syndrome component) . Majority were females (74.8%; n=80), married (58.9%; n=63) and between 41 and 50 (37.4%; n=40). The mean age was 49.4±13.7 years. The results also revealed that 43 (40.2%) of the respondents had tertiary education, 50 (46.7%) were self-employed and 67 (62.6%) earned less than N100,000 as monthly income, which is considered low (table 1).
Table 1: Socio-demographic Characteristics
SD=Standard deviation.
Life style characteristics/Medical history/Risk Factors for Dyslipidemia
Only 11 (10.3%) of the respondents smoke tobacco and were all previous smokers, 28 (26.2%) currently drink alcohol, 84 (78.5) do not consume adequate amount of fruits and vegetables, 16 (15.0%) add extra salt to their meal and 51 (47.7%) do no engage in physical activities. Thirty-five (32.7%) of the respondents reported history of hypertension while 43 (40.2%) reported family history of hypertension, similarly, 14 (13.1%) reported history of diabetes while 19 (17.8%) reported family history of diabetes (table 2).
Table 2: Life style characteristics/medical history
Prevalence of Dyslipidemia.
The prevalence of the various components of metabolic syndrome was also accessed and it was found that18 (16.8%) had reduced high density lipoprotein cholesterol, 6 (5.6%) had raised triglyceride (table 2).
70 (65.4%) of the respondents had high blood pressure, 54 (50.5%) had raised blood sugar, 48 (44.9%) had abdominal obesity, 31 (29.0%) had high BMI.
Table 3: Prevalence of Dyslipidemia in the study population
Metabolic syndrome (Dyslipidemia as a component) prevalence was accessed across socio-demographic features of respondents. The prevalence of metabolic syndrome was significantly increased across respondents’ marital status. The prevalence was 10% among singles, 44.4% among married, 55.0% among widows 66.7% among separated, and 100.0% for the divorced (x2=12.885, p=0.009). Other sociodemoraphics factors assessed did not show statistical difference (p<0.05). See table 4 below.
Table 4: Prevalence of Metabolic Syndrome (Dyslipidemia as a component) By Respondents’ Socio-demographics
*=Statistically significant; #=Fisher’s Exact Test
The multinomial logistic regression was used to identify significant predictors of metabolic syndrome. None of the socio-demographic variables included in model was found to significantly predict metabolic syndrome with the crude odds ratio, however, when the odds ratio was adjusted for confounders, it was found that age significantly predicted metabolic syndrome. The result showed that the odds of developing metabolic syndrome was about 7.5% less unlikely in persons between 21-30 years of age compared to those above 60 years of age (AOR=0.075, 95% CI for AOR=0.007-0.785, p=0.031). See table 5.
Table 5: Association of Socio-demographics and Metabolic Syndrome
COR=Crude Odds Ratio; AOR=Adjusted Odds Ratio; *=Statistically significant
Gender distribution of Dyslipidemia (a component of metabolic syndrome)
Table 6 compared the various components of metabolic syndrome across the gender of respondents. It was shown that blood pressure status (ꭓꭓ2=4.762, p=0.029) and waist circumference (ꭓ2=24.729, p<0.001) were significantly higher among females than among males, whereas high density lipoprotein cholesterol (ꭓ2=14.765, p<0.001) was significantly reduced among males than among females. BMI status, although higher among females than males, did not show statistically significant difference, but was close to statistical significance (ꭓ2=3.517, p=0.061). Also, fasting blood glucose and triglycerides did not show any statistically significant difference across gender disparity. See table 6.
Table 6: Gender distribution of metabolic syndrome components
*=Statistically significant
DISCUSSION
All through a vast array of trials and studies, it has been consistently shown that elevated levels of LDL cholesterol increase a person’s risk for the development of atherosclerotic plaques and subsequent vascular disease. In stark contrast, high-density lipoprotein (HDL) cholesterol assists in regulating cholesterol levels to prevent imbalances that would increase the risk of atherosclerotic vascular disease. Each patient’s LDL cholesterol goal is conditional on their overall cardiovascular risk, and medical therapy should be independently tailored to the patient. Managing risk factors, such as hyperlipidemia, to diminish the risk for atherosclerotic cardiovascular disease is referred to as “primary prevention.” The grounds for lowering LDL cholesterol derives from widespread epidemiologic data that reveals a positive, continuous correlation between LDL cholesterol levels, cardiovascular events, and patient mortality.
Treatment of hyperlipidemia continues to evolve as we better conceptualize the underlying pathophysiology, and we concurrently improve on preceding medical therapies.
Dyslipidemia is a global pandemic and a major risk factor for cardiovascular disease. The burden of the disease in terms of morbidity, mortality, and medical costs is immense. It is a leading cause of death for both men and women of all races and ethnicities in the United States of America [11] and WHO [10] holds it accountable for more than 4 million deaths annually, globally. Higher prevalence of dyslipidemia in Caucasians or developed nations compared to Blacks or developing nations is reported severally in literature. The American Heart Association [32] in 2006 estimated that a third of all Americans (over 100 million people) have TC levels>200 mg/dl (moderately high levels), while 34 million adult Americans have TC levels>240 mg/dl (high levels necessitating treatment). Goff et al.[33] in their Multi Ethnic Study of Atherosclerosis (MESA) which focused on dyslipidemia prevalence, treatment, and control and which involved a multicenter cohort of 6814 persons, aged 45-84 years, free of clinical cardiovascular disease at baseline, recruited from six US communities, reported an overall dyslipidemia prevalence of 29.3%. Non-Hispanic whites (males 36.9%, females 24.4%) recorded higher prevalence compared to Blacks (males 31.2%, females 29.1%).
Dyslipidemia was previously thought to be rare in Black Africa, including Nigeria. Early reports suggested that blacks have lower prevalence of dyslipidemia possibly due to genetic, nutritional, and environmental factors. [19] Some believed that protective (HDL-C) cholesterol was significantly higher in Tropical Africa, [18] similar to reports showing that populations with increased intake of fish and marine mammals have high levels of HDL-C.
Our findings show that the current state of dyslipidemia in Southern Nigeria clearly contradicts previous perceptions. Our review shows that dyslipidemia is no longer rare in Nigeria and that the gap in dyslipidemia prevalence compared to Caucasians is not only closing but that the high prevalence values obtained is comparable to Caucasian values. This transition cuts across all the focal groups evaluated. While many of the studies which were carried out in urban locations did not adduce reasons for this high prevalence value, some postulated that this may be closely linked to rapid urbanization and western diet with most urban cities saturated with fast food outlets and increasing sedentary lifestyle which contrasts with our previous highly active agrarian based lifestyle. Ironically, while it took Europe and North America centuries to experience gradual modification of lifestyle where diet based on high intake of carbohydrates replaced the traditional hunter gatherer diet rich in proteins, [34] similar transition is occurring in the developing world in decades only.
Among apparently healthy Nigerian adults, very high prevalence values were obtained – 60% (Odenigbo and Oguejiofor), [20] 60.5% (Osuji et al.), [22] and 59.3% (Sani et al.). [23] The pattern of dyslipidemia was consistently low HDL-C and high LDL-C.
Dyslipidemia is believed to be very common in both diabetic and hypertensive subjects and our findings were consistent with this expectation. Idogun et al.[27] reported a dyslipidemia prevalence of 25-69% in Nigerians with type 2 diabetes,mellitus complications, similar to the report from Akbar [35] (25-60%) among diabetic subjects in Saudi Arabia. Prevalence of dyslipidemia in Black Africans with type 2 diabetes mellitus appears indeed to be rising to very high levels. In Nigeria, the prevalence of dyslipidemia in this population was extremely high (89.0%: Ogbera et al.[25] ; 89.1%: Okafor et al.[26] ). In South Africa, Vezi et al.[36] reported a comparatively very high prevalence rate of 90.3% in the same population.
Among hypertensive cohorts, the pattern of high prevalence of dyslipidemia persists in Black Africans. Akintunde et al.[29] from Nigeria reported a prevalence of 58.9% compared to report from Congo (40.0%) by Lepira et al.[37]
CONCLUSION
Dyslipidemia is highly prevalent in Nigeria and Black Africa at a rate currently comparable with Caucasian values. The pattern and prevalence of dyslipidemia in the NigerDelta region of Southern Nigeria studied was almost consistently low HDL-cholesterol and high LDL- cholesterol. Hence, we recommend periodic fasting lipid profile screening for adult Nigerians, especially apparently healthy Nigerians of the upper social class and Nigerians with other cardiovascular disease risk factors. This will enhance early detection and treatment and reduce the high burden of this underdiagnosed and undertreated disease.
Limitation
The small sample size in this study is a major limitation factor. The findings, therefore should be confirmed with a much larger sample size..
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
REFERENCES
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