CHAPTER I: INTRODUCTION
I.1 BACKGROUND AND
RATIONALE
According to the World Health Organization (WHO),
cardiovascular diseases account for about 17 million deaths per year globally
i.e. nearly one third of the total[1].Of these cardiovascular
diseases, hypertension accounts for 9.4 million deaths worldwide and7.0% of
global disability adjusted life-years (DALY) in
2010[2].Hypertension is a serious medical condition and a key
public health problem.It has been defined as the level of blood pressure above
which intervention has been shown to reduce the associatedcardiovascular
risk[3].Hypertension is responsible for at least 45% of deaths
due to heart disease, and 51% of deaths due to stroke[1]. In
2008, approximately 40% of adults aged 25 and over had been diagnosed with
hypertension worldwide[4].The number of people with
uncontrolled hypertension increased from 605 million in 1980, to 978 million in
2008, because of population growth and ageing[5].Systolic
blood pressure (SBP) is currently highest in low-income and middle-income
countries[1,5,6];the prevalence of hypertension is highest in
the African continent at 46% of adults aged 25 and over, while the lowest
prevalence at 35% is found in the Americas[1]. In developing
countries, its morbidity andmortality are increasing due tosedentary life and
changes in lifestyle[7]. In 2015, Kingue et al. reported a
very high prevalence rate of hypertension (29.7%) in Cameroon, with the
tendency of a steady rise towards a super epidemic in the next 20 years to
come[8].Kamadjeu et al. reported in a 2003 population survey
that only 23% of all hypertensive patients were aware of their status, 10.8%
were taking antihypertensive medication and 2% were
controlled[9]. These findings suggest that medication
nonadherence might be responsible for the prevalence of high BP levels in
Cameroon. With this in mind, effective strategies have to be developed in order
to foster adherence to antihypertensive treatments by patients. The latter must
be encouraged to participate in medical decisions by actively getting involved
in the selection, adjustmentof drug treatment and in changes in lifestyle in
orderto maximize the usefulness of the
therapeuticregimen[10].
The adverse health effects of hypertensionare compounded
because manyaffected people also have other health risk factorsthat increase
the odds of heart attack,stroke and kidney failure[1]. These
risk factorsinclude tobacco use, obesity, high cholesteroland diabetesmellitus.
In 2008, 1 billion people weresmokers and the global prevalence of obesity
increased by about two-fold since 1980[1]. The global
prevalenceof high cholesterol was 39% and prevalenceof diabetes was 10% in
adults above 25 years[4].Populations around the world are
rapidly ageing and prevalence of hypertensionincreases with
age[11].
Treatment of hypertension involves both non-pharmacological
and pharmacological interventions to reduce blood pressure, as well as
assessment and treatmentof any other cardiovascular risk
factors[3].Adopting a healthy lifestyle is beneficial for all
individuals, and any patient with raised blood pressure should be encouraged to
make lifestyle changes that will reduce theircardiovascular risk. Depending on
treatment guidelines, different drug regimens may be used with differing
pharmacological actions. Historically, thiazide diuretics and beta blockers
have been the mainstay of drug therapy for hypertension, but calcium channel
blockers, angiotensin-converting enzyme inhibitors, antagonists of angiotensin
II receptors, and alpha blockers are now also widely
used[3].
Hypertension requires long term management and follow-up.
Adherence to therapy is a key component of a successful management. Adherence
to a medication regimen is generally defined as the extent to which patients
take medications as prescribed by their health care
providers[10].Both medications andlifestyle changes are
prescribed to hypertensive patients with the expectation that they will be
adherent[1,12].However, the problem of non-adherence tomedical
treatment remains a challenge for the medicalprofessions asmany patients fail
to adhere totreatment recommendations resulting inpoor health outcomes,lower
quality of life and increased health care costs[7,13].Poor
adherence to anti-hypertensive therapy is one of the biggest hindrances in
therapeutic control of high blood pressure[14].It also
compromises the efforts of healthcare systems, policy makers and health care
professionalsto improve the health of populations. Failure to adherecauses
medical and psychological complications of thedisease, reduces patients'
quality of life, wastes healthcare resources and erodes public confidence in
healthsystems[15].
Few studies have been done in Cameroon regarding
antihypertensive treatment adherence and the few that have been carried out
portray low levels of therapeutic adherence.Mbouemboue et al. found that
adherence to antihypertensive drug treatment is poor in their study population
in Garoua with an adherence rate of 12.9%[16].In a survey
conducted in the Buea Regional Hospital, it was noted that 94% of patients were
aware of the necessary measures to control their blood pressure, although 54.5%
affirmed having difficulties in respecting recommended dietary and other
lifestyle measures because they were too constraining[17].
Tufon et al. however reported a high overall level ofadherence of patients to
antihypertensive treatment (80.0%) in a rural setting (Mankon sub divisional
health centre)[18].Essomba et al. reported that 26.2% of their
study population in Douala had good adherence to antihypertensive
treatment[19]. Akoko et al. found a slightly greater adherence
rate of 49.3% among adult patients in the Bamenda Health
District[20].
Poor adherence to antihypertensive therapy is usually
associated with adverse clinical outcome of the disease andwastage of limited
health care resources[10,15,21]. The intention of addressing
adherence issues is to contribute in achieving the third sustainable goals
which seeks to «ensure healthy lives and promote wellbeing for all at all
ages»; especially target 24 which seeks to reduce by 2030, one third of
premature mortality from non-communicable diseases through prevention and
treatment and promote mental health and well-being[22].
The choice to undertake this study in the Yaounde General
Hospital was because it is a first category referral hospital with a
well-equipped cardiology service where many patients with various
cardiovascular diseases especially hypertensive patients are regularly followed
by cardiologists.
In Cameroon, there is a paucity of research regarding
adherence rates and their correlates in urban settings.This study was therefore
designed toassess the adherence statusand associated factors to
antihypertensive therapy in hypertensive patients followed-up at the Cardiology
Unit of the Yaounde General Hospital.
| 
