CHAPTER ONE

INTRODUCTION

1.1 Background

The relentless worldwide spread of non-communicable disease poses a major challenge, which

threatens the health and economics of all countries. In 2001, cardiovascular disease (CVD) was

the number one cause of death worldwide.1 The global CVD epidemic is rapidly evolving, with

the burden of disease shifting toward developing countries , as twice the deaths due to CVD now

occur in developing countries as in developed countries.2 Unlike the developed countries, the

justifiable alarm about the spread of HIV/AIDS and the old foes such as TB that are still posing

formidable challenges in many developing countries, the epidemics of CVD have insidiously

established themselves without attracting global attention or local action.3

The risk for developing cardiovascular diseases (CVD) increases progressively      with    an

individual's rate in rise of blood pressure, but the age at which BP crosses the arbitrary threshold

of hypertension depends on prior BP levels (hence "pre-hypertension"). This prompted the

United States of America’s Joint National Committee On Prevention, Detection, Evaluation, and

Treatment of High Blood Pressure (JNC-7) to promulgate the concept of ―pre-hypertension‖,

(which is defined as a systolic and diastolic blood pressure range of 120-139/80-89 mmHg

respectively) into guideline for the management of blood pressure in 2003.4 The term pre-

hypertension was coined in 1939 by Robin and Brucer based on their study,5 which showed

that future hypertension will originate from pre-hypertension and that the mortality rate of

people with pre-hypertension roughly double that of individuals with normal blood pressure

(<120/80mmHg); however they did not formulate treatment guideline for pre-hypertension.

Following their postulation various terminologies have been used to describe pre-hypertension

1

including ―transient hypertension‖ in 1940s,6 borderline hypertension in 1970s,7 high normal

blood pressure in 1990s,8 and most recently pre-hypertension in 2003.4 Regardless of the

terminology, this condition is a precursor of hypertension and     is associated with excess

morbidity and mortality from cardiovascular disease.6,7

The prevalence of pre-hypertension is high worldwide and varies with differences in socio-

demographic characteristics and cardiovascular risk factors of the population studied.7 The

prevalence of pre-hypertension among U.S. adult population was 31% in 2004.9 A cross-

sectional study among adult family practice population in Canada show prevalence of pre-

hypertension of 30.6% in 2008.10 The prevalence of pre-hypertension among Ghanaian adults in

the Ashanti region of Ghana, West Africa was found to be 40% in 2008.11 A retrospective study

among newly presenting diabetics in Maiduguri, Nigeria show a prevalence of 36% in 2008.12

The prevalence rates of 58.7% (men 59.2%, women 58.2%) was observed among adult Hausa

and Fulani ethnic groups in Sokoto, Nigeria in 2010.13

Like hypertension, adults with pre-hypertension are known to have a higher prevalence of other

Cardiovascular disease risk factors, with about 93% of pre-hyp