PREVALENCE AND PATTERN OF DYSLIPIDAEMIA AMONG ADULT HYPERTENSIVES IN THE GENERAL PRACTICE CLINIC OF UNIVERSITY OF BENIN TEACHING HOSPITAL BENIN CITY, EDO STATE.

SUMMARY

This study was aimed at determining the prevalence and pattern of dyslipidaemia among adult hypertensive patients at the General Outpatient Department (GOPD) of the University of Benin Teaching Hospital (UBTH), Benin City.

The study was carried out using three hundred (300) consecutive adult hypertensive patients (aged ≥ 18 years) attending the General Practice Clinic of UBTH and who met the inclusion criteria for the study. In addition to the collection of demographic variables, blood lipid profiles were assessed.

The mean age of the respondents was 47.6 + 12.5 years. The age ranged from 18 to 80 years, with those aged 40 to 59 years accounting for nearly 60% of them. One hundred and fifty nine (53.0%) of the patients were females while 141(47.0%) were males, with a female to male ratio of 1.13:1. The body mass index revealed that 134 (44.7%) of the respondents were over weight while 77 (25.7%) were obese.

Sixty–one (20.3%) of the respondents had elevated total cholesterol levels

(≥200mg/dl or ≥ 5.26mmol/l), 77 (25.7%) had elevated levels of triglyceride (> 150mg/dl or > 1.7mmol/l), 107 (35.7%) had depressed levels of HDL (≤ 40mg/dl or ≤ 1.05mmol/l) while 78 (26.0% had elevated levels of LDL (≥ 130mg/dl or ≥ 3.35mmol/l).

The mean + SD atherogenic index which is derived from the ratio of TC:HDL-C was found to be 3.9+ 2.2. Eighty-two (27.3%) of the respondents were at cardiovascular risk (MAI > 4.5). The coronary heart disease risk of the respondents, which is derived from the ratio of HDL-C: TC showed that 174 (58%) had low to average risk and 77 (25.7%) were at high risk (CHD ratio <0.18).

The study found that depressed HDL level 107 (35.7%) was the most prevalent dyslipidaemia among the lipid components. There was no statistically significant relationship between all the lipids components and gender. However, there was a statistically significant relationship between HDL-C levels and body mass index. The finding could be explained that depressed HDL-C correlates with over weight and obesity. This could explain the significant difference in mean serum HDL-C levels among the BMI groups. Therefore, strategies should be designed for weight reduction in adult hypertensives to prevent cardiovascular disease. There was a statistically significant association between mean atherogenic index and hypertension severity. There was also a statistically significant association between coronary heart disease risk ratio and hypertension severity.

The study concluded that dyslipidaemia is prevalent among adult hypertensive patients in our environment. This corroborated the findings in the past study on the submission that dyslipidaemia is an important issue of concern that need  attention in hypertensives.

The study recommended that there should be a change in the attitude of physicians to enhance the screening of hypertensive patients for dyslipidaemia and its management. In addition, severity of hypertension should be determined for all patients at presentation to know those at risk of cardiovascular complications. Furthermore, all hypertensive patients whose lipid profiles have been determined should have their mean atherogenic index (TC: HDL – C) ratio and coronary heart disease risk (HDL – C : TC) ratio calculated to know those who are at cardiovascular risk.

TABLE OF CONTENTS                                                                                         Page

Title page…………………………….……………………………………………i

Declaration.................................................................................................................................................. ii

Certification................................................................................................................................................ iii

Dedication.................................................................................................................................................. iv

Acknowledgement..................................................................................................................................... v

Table of contents...................................................................................................................................... vi

List of tables.............................................................................................................................................. vii

List of figures............................................................................................................................................. ix

List of abbreviations and their meaning................................................................................................. x

 

Summary…………………………………………………………………………...1

Chapter one: Introduction………………………………………………………..3

Chapter two: Literature Review…………………………………………………9

Chapter three: Materials and Methods………………………………………..38

Chapter four: Results…………………………………………………………….46

Chapter five: Discussion………………………………………………………...70

Conclusion………………………………………………………...76

Limitations of the study …………………………………………..77

Recommendations………………………………………………..77

References ………………………………………………………………………..79

Appendices

CHAPTER ONE

1.0       Introduction

In the past few decades, significant changes have occurred in the pattern of health and disease in many developing countries, including Nigeria. Non-communicable diseases which include hypertension and diabetes mellitus have become important causes of morbidity and mortality in Nigeria¹. The prevalence of hypertension among African Communities is increasing with the aging population and lifestyle changes associated with rapid urbanization and modernization^2,3.

A survey by a committee set up by the Nigerian Health Minister in the early 1990s revealed that 9.3% of Nigerians over 15 years of age were hypertensive and 2.2% were diabetic¹.  Previous surveys also projected that hypertension prevalence rates in Nigeria would be of the order of 17-20 percent or more by the year 2010².  The most prevalent cardiovascular disease is hypertension and is an acknowledged potent risk factor in the development of coronary heart disease, stroke, congestive heart failure, renal insufficiency and atherosclerosis^1,2,3. It is also associated with elevated serum lipids

levels^2,3.  Abnormalities in plasma lipoprotein metabolism play a central role in the pathogenesis of  arteriosclerosis ⁴. Patients with multiple cardiovascular risk factors are at much greater risk for cardiovascular disease (CVD) events than those with one risk

factor^4,5.  This has been recognized in recent treatment guidelines that emphasize the

need to quantify a person’s overall CVD risk^4,5-.  

Hypertension as defined according to the Seventh Report of the Joint National

Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure

(JNC7) in United States of America is blood pressure (BP) of equal to or more than

¹³⁰/₈₀mmHg or ¹⁴⁰/₉₀mmHg depending on risk factors⁶. The current recommendation in Nigeria is BP > 140/90mmHg.^1,2. Two or more antihypertensive medications (thiazide, beta-blockers, calcium channel blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers) will be required to achieve goal of BP (<140/90mmHg, or <130/80mmHg), for patients with diabetes mellitus and chronic kidney disease⁶. The diagnosis of hypertension is based on two or more measurements of blood pressure spaced 2 weeks apart^2,6.

Hypertension may be of unknown aetiology (primary or essential hypertension). It may also result from kidney disease, including narrowing (stenosis) of the renal artery (renal hypertension), endocrine diseases (such as Cushing’s disease or phaeochromocytoma) or disease of the arteries (such as coarctation of the aorta), when

it is known as secondary or systemic hypertension^1,6. Hypertension is symptomless until the symptoms of its complications develop. Complications that may arise from hypertension include atherosclerosis, heart failure, cerebral hemorrhage and kidney failure, but treatment may prevent their development^1,6.

The main goal of treatment of hypertension is to reduce the cardiovascular morbidity and mortality and mitigate the known modifiable risk factors that interact with hypertension to increase cardiovascular risk^3,7,8,9.  These modifiable risk factors include: consumption of saturated fats and cholesterol, excessive consumption of salt, insufficient intake of calcium or potassium, an increase in the caloric content in the diet, smoking, obesity or excessive drinking of alcoholic beverages¹⁰.

Blood pressure levels have been shown to be positively related to the risk of major coronary heart disease events^7,11. This is possibly due to the association of hypertension with hyperlipidaemia, either as a component of a metabolic syndrome or as a result of drugs (β-blockers, thiazide diuretics, angiotensin-converting enzyme inhibitors and calcium channel antagonists) used in its treatment ^7,11.  The prevalence rate of hypertension in Nigeria is said to be low compared to that of the Americans but the

mortality associated with it in Nigeria remains high^2,3,12. Some of the reasons for this include poverty, high cost of newer antihypertensive drugs and attitude of the key players in the management of hypertension.  The key players include doctors, pharmacists, nurses, the patients and their families.

These attitudes include: on the part of doctors, is inadequate health education of the patients. While on the part of the pharmacists, on patients’ request, they substitute drugs that are cheaper without necessarily having the same efficacy with the prescribed drugs.  On the part of the nurses, there is also inadequate health education of the patients on the proper use of their medications. On the part of the patients, there is poor compliance to drug therapy. Lastly, on the part of the families they do not support the patients or monitor them as regard compliance to drug therapy and modifiable risk factors as earlier stated.

Dyslipidaemia is defined as an increase or decrease in concentration of one or

more plasma or serum lipids^4,13. Dyslipidaemia is a known component of cardiovascular disease risk factors (dyslipidaemia, hypertension, diabetes mellitus, obesity, c-reactive protein, cigarette smoking, male above the age of 45years, female above the age of 55years and family history) and metabolic syndrome (hyperlipidaemia, obesity, hypertension and diabetes mellitus)^13,14.

Recent studies of lipid disorders show that a serum total cholesterol of less than

200mmg/dl or less than 5.26mmol/l is associated with low risk of cardiovascular events^{13, 14}. High density lipoprotein cholesterol levels of less than 40mg/dl or less than 1.05mmol/l, low density lipoprotein cholesterol levels of greater than 140mg/dl or greater than 3.68mmol/l and triglyceride levels of equal to or greater than 200mg/dl or greater than

2.27mmol/l are undesirable^{13, 14.} 

Most physicians do not request for serum lipid measurement in management of their hypertensive patients due to high cost of the investigations and lack of facilities to carry out the test in their practice setting.  This study is designed to provide data that will guide physicians in managing hypertensives especially with regard to their lipid profiles.

Family physicians play a prominent role in the management of non-communicable diseases, notably hypertension and diabetes mellitus.  Family physicians also provide continuous life-long care for hypertensive patients. There is a link between dyslipidaemia

and hypertension ^13,14.  A new analysis from the physicians health study found that higher levels of total cholesterol are associated with an increased risk of hypertension in middle aged and older men^13,14. Therefore, the management of hypertension with concurrent dyslipidaemia will prevent and safeguard against cardiac events.

Measures to reduce the burden of dyslipidaemia in high-risk patients include early screening so that appropriate treatment can be started before the development of complications that might cause morbidity and mortality. Life style modifications which include exercise, moderation in alcohol intake, weight reduction, cessation of smoking and healthy eating should be instituted and adhered to¹⁵.

This study was therefore set up to find out the prevalence and pattern of dyslipidaemia in hypertensives in this environment with a view to encouraging physicians and patients to comply with its management to decrease cardiovascular complications.

 

1.1            Statement of the Problem 

Dyslipidaemia is one of the components of cardiovascular disease risk factors and

metabolic syndrome^13,14. The prevalence of dyslipidaemia and concurrent hypertension is increasing in developing countries including Nigeria^1,2. Non – communicable diseases which include hypertension and diabetes mellitus have become an important cause of morbidity and mortality in Nigeria.¹⁶

Most physicians tend to have poor attitude to screening their hypertensive patients for dyslipidaemia despite the fact that primary and secondary causes of dyslipidaemia abound in Nigerian communities¹⁶. Some of the secondary causes of the dyslipidaemia include obesity, diabetes mellitus, cigarette smoking and nephrotic syndrome ^3,16. Lipid assays should be encouraged as part of management of diseases to reduce the risk of atherosclerosis and their sequelae.

The prevalence and pattern of dyslipidaemia are needed as a basis for encouraging a change in physician’s attitude and patients life styles. The essence of this study was to know the prevalence and pattern of dyslipidaemia, as it co-morbids in concurrence with hypertension in this part of the country.  Results from this study will assist in encouraging doctors, notably family physicians who manage hypertensive patients on a continuous basis to prevent the occurrence, monitor them periodically for detection of early onset of dyslipidaemia, and when present, to promptly institute appropriate treatment.

 

1.2       Justification for the Study

Despite the negative contribution of dyslipidaemia to morbidity, quality of life and health care cost, there are few studies on prevalence and pattern of dyslipidaemia in Nigeria. The prevalence of concurrent dyslipidaemia and hypertension may be underreported.

Dyslipidaemia together with hypertension may predict a marked increase in the incidence of cardiovascular events in Nigeria.  Many studies done in Nigeria were for hypercholesterolaemia only.

This study is expected to provide useful information on the current prevalence and pattern of dyslipidaemia in adult hypertensives attending the General Practice Clinic of the University of Benin Teaching Hospital, Benin City, Nigeria. It is hoped that the findings from this study would be of benefit to family physicians and other doctors in their practice settings. It may also inform the need for further study and also guide development or review of guidelines.

 

1.3       Aim and Objectives 

1.3.1 Aim

The aim of the study was to determine the prevalence of dyslipidaemia among adult hypertensive patients presenting at the General Practice Clinic of the University of Benin Teaching Hospital to guide in its management and prevention of cardiovascular disease complications.

 

1.3.2 Specific Objectives

1. To determine the prevalence dyslipidaemia among study subjects.
2. To determine the of pattern of dyslipidaemia among the study subjects.
3. To determine the relationship between BMI, age, sex and serum lipids and the severity of hypertension.

To determine the mean atherogenic index (TC: HDL-C) ratio and coronary heart disease risk (HDL-C:TC) ratio in these subjects

PREVALENCE AND PATTERN OF DYSLIPIDAEMIA AMONG ADULT HYPERTENSIVES IN THE GENERAL PRACTICE CLINIC OF UNIVERSITY OF BENIN TEACHING HOSPITAL BENIN CITY, EDO STATE.

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