CHAPTER ONE: INTRODUCTION

1.1. Background

Hypertension is defined as systolic blood pressure (SBP) of 140 mmHg or higher and or diastolic blood pressure (DBP) of 90 mmHg or higher [1].  In children, hypertension is defined as a systolic BP (SBP) or a diastolic BP (DBP) greater than or equal to the 95th percentile for gender, age, and height or greater than or equal to 130/80 mmHg, depending on the age of the child, measured on at least three different occasions [2,3]. The prevalence of hypertension has increased, especially in low and middle-income countries (LMICs), with a global estimate of 31.1% of adults which is about 1.28 billion people [4,5]. Hypertension is now a significant problem in groups previously thought to be at low risk such as rural populations, poor households, and younger people [6]. The reported overall prevalence of childhood hypertension is approximately 3.5% worldwide [2]. Hypertension in children is increasingly recognized as a serious public health problem, not only because of its rising prevalence but also because growing evidence indicates that elevated blood pressure early in life has detrimental lifelong cardiovascular effects [7].

The aetiology of hypertension in childhood depends on whether it is primary or secondary, as in adults. Primary Hypertension or essential hypertension is complex and just like in adults has no obvious cause, but has been associated with several risk factors attributed to early life environment interacting with genetic susceptibility [8]. Certain non-modifiable risk factors such as family history of hypertension, kidney disease, and other systemic diseases, age, race, ethnicity, and birth weight, have been attributed to HTN in adolescents [3]. Modifiable risk factors like obesity, sedentary behavior, diet (with high calories, salt, and fat), physical inactivity [3] malnutrition, certain sleep disorders, low socio-economic status, smoking, and drugs have also been associated with HTN in adolescents [9]. Secondary hypertension, on the other hand, is HTN having an underlying identifiable cause which could be; renovascular, cardiovascular, neurological, endocrine, tumoral, and systemic [3].

Children with hypertension may be subject to various short and long-term complications if not diagnosed and treated appropriately on time. They can experience sudden acute complications such as hypertensive encephalopathy, stroke, and even cerebrovascular accidents and congestive heart failure [10]. Even when the hypertension is not severe, it chronically contributes to end-organ damage especially when associated with other cardiovascular risk factors or  diseases [10]. The most common of these end organ damages are left ventricular hypertrophy (LVH)[10,11], increased carotid intima-media thickness, higher pulse-wave velocity, arterial calcification, arterial thickness, and atherosclerotic changes in adulthood [12,13].In addition, reports of retinal abnormality and lower glomerular filtration rates with proteinuria are also long-term complications of HTN [8,10,14].

In India, Vasudevan et al in 2022 studied the prevalence and associated factors of high blood pressure among adolescents which noted a prevalence of 35.1% in children 10 to 12 years, and 25.1% in children 13 years and older. The associated factors in this study were obesity, high fasting blood glucose, and high hemoglobin A1C. Yang et al in 2022 in China found the prevalence of hypertension in adolescents to be 9.4% over five years. The associated factors found were; increased body mass index and living in rural areas. In Africa, Noubiap et al noted a pooled prevalence of hypertension in children and adolescents to be 5.5% in 2017; obesity was pointed out as a strong predictive factor in this study. In 2021 Ouzna et al studied the prevalence of elevated blood pressure in northern Africa which was noted to be 13.6%. Being overweight, family history of hypertension, and sedentary lifestyle were all noted as risk factors for hypertension in these children. A study done in Nigeria in 2021 by Shokunbi and Ukangwa revealed the prevalence of hypertension in school adolescents to be 19.3% and an increase in age and, the addition of table salt to meals were identified risk factors.

 In Cameroon, kamdem et al 2023 studied the prevalence of high blood pressure among adolescents, which revealed a prevalence of 3%, with overweight, physical inactivity, and glucose homeostasis abnormalities noted as risk factors. In the North West region, Niba et al in a study done in 2023 revealed a prevalence of 39.2% of secondary school adolescents to be hypertensive and pre-hypertensive with increased waist circumference being associated with hypertension in this population. However, this study only assessed the relationship between measures of adiposity and hypertension in these adolescents; no other risk factors were assessed. We are therefore carrying out this study to evaluate other risk factors of high blood pressure among secondary school adolescents in the Bamenda municipality.

1.2. Problem Statement

Despite the rising prevalence and evident complications, care for hypertension in the pediatric population remains inadequate in our setting. Not much is done to prevent hypertension in children in our setting, probably because of limited knowledge of the multiple associating factors, lack of material and human resources, poor follow-up, and conflicting recommendations by different Western guidelines, which are not fully applicable in our setting. In addition, the fact that the blood pressure norms in children vary with gender, age, and height [2], makes it cumbersome and time-consuming to interpret, especially in settings where there are limited clinicians for many patients. This makes the blood pressure in the pediatric population rarely assessed, and most hypertensive adolescents present in very critical situations (stroke, encephalopathy, kidney failure, etc) which can become fatal.

1.3. Justification

Hypertension in adolescents is becoming a major concern, not only because of its rising prevalence and acute complications but also because of evidence suggesting that hypertension tracks from childhood to adulthood. It is therefore important to identify the associating factors of hypertension in this population. The two studies done in the region so far have only assessed the association between measures of adiposity [15] and the contribution of linear growth components with hypertension in secondary school adolescents [16]. We therefore aimed to assess the association between some genetic, lifestyle, and environmental risk factors, with hypertension in these secondary school adolescents.

To our current knowledge, no previous study has been conducted in the North West region that aimed to assess the various risk factors associated with high blood pressure among adolescents in this particular region. Knowledge of this will fill knowledge gaps that will assist in the prevention and early diagnosis of hypertension in adolescents in this region. Thereby also contributing to the achievement of Sustainable Development Goal number 3 which aims at attaining good health and well-being for all

1.4. Research Goal

To determine the prevalence and evaluate the factors associated with high blood pressure among secondary school adolescents in the Bamenda municipality.

1.5. Research Questions

1. What is the prevalence of high blood pressure among secondary school adolescents in the Bamenda Municipality?
2. What are the socio-demographic characteristics of hypertensive adolescents in the Bamenda Municipality?
3. What are the factors associated with high blood pressure among secondary school adolescents in the Bamenda Municipality?

1.6. Research Hypothesis

• Null Hypothesis: There is no relationship between some selected factors and high blood pressure among secondary school adolescents in the Bamenda municipality.
• Alternative Hypothesis: There is a significant association between some selected factors and high blood among secondary school adolescents in the Bamenda municipality.

1.7. Research Scope

This study scope is adolescents, 10-19 years in secondary schools in the Bamenda municipality.

1.8. Research Objectives

1.8.1. General Objectives

To determine the prevalence and evaluate the factors associated with high blood pressure among secondary school adolescents in the Bamenda municipality

1.8.2. Specific Objectives

1. To determine the prevalence of high blood pressure in secondary school adolescents 10-19 years, in the Bamenda Municipality.
2. To describe the socio-demographic characteristics of hypertensive secondary school adolescents within the Bamenda municipality.
3. To evaluate the clinical, physical, and environmental factors associated with hypertension in these secondary school adolescents.