How Common Is Hypertension?

Hypertension is a chronic non-communicable disease that affects people of all age groups, sex and socio-economic classes. There is a high global burden of hypertension with an estimated 1.13 billion people worldwide reported to have hypertension, with most (two-thirds) living in low- and middle-income countries (LMICs). While in 1990, high systolic blood pressure (BP) was the seventh-leading risk factor by attributable disability-adjusted life-years (DALYs), in 2019, it had become the leading risk factor. The African Region of the World Health Organization (WHO) has the highest prevalence of hypertension (27%). The increase in LMICs is due mainly to a rise in hypertension risk factors in their populations.

Accounting for 9.4 million deaths annually, hypertension is the leading cause of death and disability-adjusted life-years worldwide. Reports from diverse sources also show that countries in the Africa sub-Saharan region suffer disproportionately from this burden, as reflected in age-standardized death rates which are higher than those in many other parts of the world.

The prevalence of undiagnosed hypertension has been reported to vary among different population groups/geographical locations, occupational endeavours, gender and socioeconomic groups. In sub-Saharan Africa, the burden of hypertension has been on the increase over the past few decades. In West Africa, the prevalence of hypertension ranges from around 12% among the physically active population, and up to 68% among those that are sedentary.

The World Health Organization estimated the prevalence of hypertension (BP>140/90mmHg) in Nigerian adults over the age of 18 at 27.8%, comprising 28.1% and 27.5% in men and women respectively, against a background of 22% world prevalence. By comparison, in another report describing another age set of over 25, the prevalence rates were put at 40% worldwide and 46% in Africa. More specifically, in a recent meta-analysis of twenty-seven studies involving 27,122 participants in Nigeria aged over 15, the pooled estimate of hypertension prevalence was 28.9% in both sexes, 29.5% and 25% in men and women respectively. This analysis also revealed a mean SBP of 128.6mmHg, mean DBP of 79.4 mmHg, and hypertension prevalence of 30.6% and 26.4% in urban and rural areas respectively.

Prevalence of Hypertension in Nigeria

In Nigeria, hypertension is the commonest non-communicable disease (NCD), with the prevalence of hypertension having a much narrower range of between 12% and 36.8%. However, the prevalence of undiagnosed hypertension among different population groups in Nigeria still requires further attention and intervention due to a lack of data. Although the NCD Survey of the Federal Ministry of Health and Social Services published in 1997 remains the largest survey reporting hypertension prevalence in Nigeria, several other reports, including meta-analyses have since appeared providing updated prevalence rates. Thus, current prevalence rates in adults would range broadly from 20% - 40%, using the 140/90 mmHg standard level. Additionally, the age-standardized prevalence rates and the associated morbidity are higher in Africa, Nigeria included, than in many other regions of the world.

With a hypertension prevalence of around 30.6%, Nigeria, with its large population, contributes a significant proportion to the overall burden of hypertension in the region. The number of Nigerians aged 20 years and above with hypertension was estimated at 27.5 million for the year 2020 and has been projected to rise to 39.1 million by the year 2030.

Associated with this situation are the low awareness rates of 15-30%, treatment rates of around 20% and control rates of around 10%, which might relate to peoples’ attitudes and lack of resources. The sheer numbers affected and the relatively high cost of investigations and medicines constitute a financial burden. The direct cost of hypertension management is enormous for a country where the majority of the patients may spend over 10% of their income on medications.

From individual study estimates, the highest prevalence of hypertension (SBP ≥ 140 mmHg or DBP ≥ 90 mmHg) was recorded in an urban community in Kaduna State, North‐west Nigeria, at 55.9% in 2018, with the lowest prevalence estimated in Ibadan Oyo State, South‐west Nigeria, at 9.3%. When the hypertension prevalence survey was done across the geopolitical zones, the estimate in the four zones was relatively similar and above 30%. The highest prevalence was in the South‐East at 33.3%, closely followed by the North‐Central with a prevalence of 32.2%; while the North‐West had 31.9%, and the South‐West had 30.2%. The North‐East and the South‐South had a prevalence of 24.7% and 27.6%, respectively.

Although no significant difference, the prevalence was slightly higher among women (30.4%), than among men (29.5). Across both sexes, the prevalence was consistently higher among urban dwellers (33.5%) than among rural dwellers (25.5%).

This analysis shows evidence of substantial regional variation in the prevalence of hypertension in Nigeria, which ranged from 25% to 33% across the geopolitical zones. The highest prevalence was in the South‐East and North‐Central at 33.3% and 32.2%, respectively.

What Causes Hypertension Among Nigerians

Hypertension is often not well investigated in the country due to a dearth, and high costs of diagnostic laboratory investigations, and a low index of suspicion.

Hypertension is globally prevalent and is a common cause of premature deaths all over the world. It is one of the known risk factors for cardiovascular diseases. Despite the considerable progress that has been made in the prevention, detection, treatment and control of hypertension over the years, the disease remains a major cause of global morbidity and mortality, and of significant public health importance. Hypertension is known to increase the risk of stroke, myocardial infarction, congestive heart failure, sudden cardiac death, peripheral vascular disease and renal insufficiency. Furthermore, the onset of hypertension has been linked to several risk factors such as ageing, obesity, sedentary behaviour, family history of hypertension, African ancestry, smoking, use of contraceptive pills and excess intake of alcohol and salt.

Also, some additional risk factors have been reported among Nigerians, and these include high and low (excluding middle) socio-economic status. Other factors that may influence the development of hypertension include stress (with the evidence relatively low)