PREVALENCE AND FACTORS ASSOCIATED WITH PRESENCE OF MICROALBUMINURIA IN PATIENTS WITH ESSENTIAL HYPERTENSION SEEN AT THE GENERAL OUTPATIENT CLINIC OF FEDERAL MEDICAL CENTRE, ABEOKUTA

CHAPTER ONE

INTRODUCTION

Hypertension (HTN) is an important worldwide public health challenge because of its high and increasing prevalence and concomitant risks of cardiovascular (CV) and renal diseases. In fact, it has been described as the most powerful, highly prevalent, independent, modifiable risk factor for cardiovascular disease (CVD) at the population level. 1,2 The burden of HTN worldwide is so enormous that it has been projected that the approximately one billion (15- 20%) of the world’s population currently being affected 3-8 will increase to 1.56 billion by year 2025 and sub-Sahara African shall be the most affected. Hypertension (HTN) is a common condition amongst Nigerians. The prevalence is alarmingly on the increase 6,9 as a result of westernization and urbanization. Some patients with essential HTN (EHTN) manifest microalbuminuria (MAL) – an abnormal (30-300mg/24hours) urinary albumin excretion. It has long been established that albuminuria is the principal marker for chronic kidney disease (CKD). 10-14 In fact, MAL is regarded as the most sensitive parameter for the detection of early kidney damage. More recently, MAL has become widely recognized as an independent risk indicator for CVD morbidity and mortality for patients with HTN and diabetes. 13,15,16,17,18, 19, 20,21

CVD morbidity and mortality as well as CKD are preventable if hypertensive nephropathy is detected at the microalbuminuric stage and appropriate pharmacotherapy and other measures are instituted. Studies have overwhelmingly shown that pharmacologic blockade of renin- angiotensin-aldosterone system (RAAS) by Angiotensin Converting Enzyme Inhibitors (ACE- I) and/or Angiotensin Receptor Blockers (ARB) provides effective reduction of MAL and

blood pressure (BP), and long term prevention of CV events beyond BP reduction. 22,23,24,25,26,27,28,29,30-33 This agents are capable of preventing, reversing or slowing down progression of hypertensive or diabetic nephropathy.

Surprisingly, a very wide gap exists between what is known and what is currently being practiced. Despite compelling data and the well known correlation between MAL and CV risks, at present only a minority of patients with diabetes and very rarely individuals with HTN are screened for microalbuminuria 15,34 especially in a developing country like Nigeria. The prevalence of MAL in essential HTN has been determined by several studies and different prevalence rates have been reported among Caucasians. 16,35,36 Only very few of such studies have been carried out in Nigeria. 37,38 Hence, early detection of MAL via simple, point-of-care screening method shall be the focus of this study. Also emphasis shall be laid on the clinical pattern of MAL, vis-a-vis influencing factors, among the subjects. This will enable early risk stratification of hypertensives and institution of the right choice of drugs and other measures to forestall CVD progression. This brightens the management outcome, betters the prognosis, improves the quality of life, increases life expectancy and more importantly helps prevent expenditure of the scarce Nigerian health resources on the management of hypertensive complications notably cardiac, cardiovascular, retinal and renal. Family Physicians who, as doctors of first contact, diagnose and initiate antihypertensive therapy in most cases are well placed for this cost effective, result oriented and secondary preventive step towards reversing the trend of CKD and CVD.

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AIM AND OBJECTIVES OF THE STUDY

General Objective (Aim) The general objective of the study is to describe the prevalence and factors associated with presence of microalbuminuria among adult Nigerian patients with essential hypertension in order to inform early detection and control practices.

Specific Objectives The specific objectives are; 1. To determine the prevalence of MAL among patient with essential HTN. 2. To describe the sociodemographic and clinical characteristics of these patients. 3. To identify factors associated with presence of MAL in the study population.

JUSTIFICATION FOR THE STUDY Hypertension is the most important modifiable risk factor for CVD which is a leading cause of death in Western Countries 35,39 accounting for more than one third of all deaths.

This is due mainly to the steady increase in the prevalence of hypertension and diabetes both of which have now reached the proportion of worldwide epidemic. Unfortunately, this epidemic is projected to continue unabated such that by year 2025, 1.56billion of the world population will be hypertensive. This will translate to a further rise in the number of deaths from CV complications and CKD.

Recent epidemiological survey reported a range of 31-44% prevalence of hypertension (HTN) in the Western world.

Unfortunately, HTN is also the commonest risk factor for CKD, the prevalence of which is also alarmingly on the increase.

By virtue of the ever increasing rate of urbanization and westernization, the prevalence of HTN among black populations is expected to rise sharply. As such, by the end of the next 2 decades, the consequent CVD mortality and morbidity shall be overwhelming for the African economy. Sub-Sahara Africa, which includes Nigeria, will be the most affected.

Nigeria with her perennial health concerns with infectious diseases needs to be highly proactive towards prevention of non-communicable diseases and their consequences. This mandates the need for an early identification of patients who are at increase risk of CVD and CKD for a better stratification.

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Early identification of those who are at risk is of paramount importance because it could set the stage for a more rational therapeutic approach by allowing direct additional measures to those who need them the most.

Early detection of microalbuminuria (MAL) via a simple, inexpensive and highly sensitive screening method for CVD risk stratification and hence aggressive therapeutic approach has

been recommended by the JNC-VII and ESH –ESC. 35,39 Different prevalence rates (5-40%) have been reported among Caucasians. There is a dearth of studies on the prevalence of MAL and its clinical pattern among patients with essential HTN with an implied consequence of very poor CVD risk stratification in this part of the world, hence the choice of the title.

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