Hypertension Disease Background

Introduction

Hypertension is the medical term for high blood pressure. 

Epidemiology

The World Health Organization (WHO) estimated hypertension to occur in 1.28 billion adults aged 30-79 years old and two-thirds of these are living in low- and middle-income countries. About 46% of adults with hypertension are not aware that they have hypertension while about 42% of adults with hypertension are diagnosed and managed, and only 21% (1 in 5 adults) have controlled hypertension.

The global prevalence of hypertension using the 2017 American College of Cardiology (ACC) and American Heart Association (AHA) definition of hypertension was estimated in 2019 at 1.3 billion. The prevalence of hypertension in Asia is approximately 49.4% in men and 43.6% in women. 

The Philippine Heart Association’s PRESYON-4 reported that the point prevalence in the Philippines increased to 34% in 2020 from 28% in 2013. Nevertheless, the National Nutrition Survey reported that the prevalence decreased from 23.9% in 2013 to 19.2% in 2018 among those 20-59 years old and 41.2% in 2015 to 35% among the elderly in 2018.

Hypertension remains to be one of the top causes of morbidity and mortality in Asia and although the level of awareness, treatment, and control are steadily increasing, they remain to be low.

Pathophysiology

Hypertension may be due to multiple factors including neural and chemical disorders, alterations of vascular caliber and elasticity, cardiovascular reactivity, and blood volume and viscosity.  

Blood pressure maintenance is complex and involves several physiological mechanisms including arterial baroreceptors, the renin-angiotensin-aldosterone system, atrial natriuretic peptide, endothelins, and mineralocorticoid and glucocorticoid steroids, which together manage the degree of vasoconstriction or vasodilation within the systemic circulation, and the retention of water and sodium to maintain adequate circulating blood volume and dysfunction in any of these processes can lead to hypertension development.  

Sympathetic neural activation modulates hypertension by enhancing vasoconstriction and vascular remodeling, producing renal renin via beta 1 adrenergic receptors in the juxtaglomerular apparatus and increasing renal sodium resorption and inflammation. Nephrogenic mechanism attributes BP increase to either decreased renal blood flow or to renal parenchymal disease.   

Classification

Classification of Blood Pressure  

The classification must be based on the average of ≥2 properly measured, seated blood pressure readings on each of ≥2 office visits. Various consensus guidelines are available as standard references for the definition of hypertension.¹

• Stage 1: Uncomplicated hypertension (without hypertension-mediated organ damage [HMOD], diabetes, established cardiovascular disease [CVD] or chronic kidney disease [CKD] stage ≥3)
• Stage 2: Presence of HMOD, diabetes, or CKD stage 3
• Stage 3: Presence of established CVD or CKD stage 4 or 5