Recognising the risks: The growing burden of cardiovascular disease
Research estimates that controlling major risk factors like high blood pressure, obesity, poor diet, and smoking could reduce the risk of heart attacks, strokes, and other cardiovascular conditions by 30 to 80 per cent, depending on the risk factor and population.
A major study, published in the Journal of the American College of Cardiology (JACC), has found that almost all heart attacks, strokes, and heart failure cases are preceded by at least one identifiable warning sign.
Researchers examined key risk factors such as high blood pressure, elevated blood sugar, abnormal cholesterol levels, and smoking. The findings challenge the common belief that heart events occur without warning, and instead highlight the critical importance of regular health screenings, preventive care, and lifestyle changes to reduce risk.
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Researchers examined health records from more than 9 million adults in South Korea and nearly 7,000 adults in the United States (US) over several years. They found that over 99 per cent of people who later had a heart attack, stroke, or heart failure had at least one "nonoptimal" or elevated risk factor before their first event.
In more than 93 per cent of the cases, individuals had two or more elevated risk factors.
The study focused on four traditional cardiovascular risk factors and their so-called "nonoptimal" levels: blood pressure, total cholesterol, fasting glucose (blood sugar), and tobacco use (past or present smoking).
Risk factors
They defined "nonoptimal" levels based on thresholds from the American Heart Association's ideal cardiovascular health definitions, for example, blood pressure equal to or above 120/80 mm Hg or being on treatment. Among these risk factors, high blood pressure (hypertension) was the most common, appearing in over 95 per cent of the South Korean cohort and more than 93 per cent of the US cohort.
The results held even when applying stricter clinical thresholds, such as blood pressure at or above 140/90, cholesterol at or above 240, glucose at or above 126, or current smoking. Under these stricter definitions, at least 90 per cent of patients still had at least one major risk factor before their cardiovascular event.
This pattern was consistent across different sexes, ages, and types of cardiovascular events, including heart attack, stroke, and heart failure. Even among women under 60, a group often considered at lower risk, more than 95 per cent had at least one nonoptimal factor before their first cardiovascular event.
The authors suggest that these findings challenge the idea that cardiovascular events "strike out of nowhere." Because almost all individuals had detectable risk factors before their first event, there is a significant opportunity for earlier detection and intervention.
It is, however, important to note that "nonoptimal" doesn't always mean clinical disease. The study included risk factor levels above the ideal but below the threshold that would lead to a diagnosis or treatment; hence, some people might have had modest elevations that would not have been flagged in standard clinical practice.
Moreover, the observational data show an association rather than direct proof that reducing these risk factors will prevent every event. The findings align with current understanding of cardiovascular risk but don't replace the need for clinical trials and individual medical assessment.
The study also focused on four major, well-studied modifiable factors; there are other risk factors, such as genetics, inflammatory markers, and environmental exposures. Additionally, "past smoking" is broad and doesn't fully capture details like how much or how long someone smoked.
Finally, the results are strong in the populations studied, South Korea and the US, but may differ in other regions, ethnicities, healthcare systems, or populations with different baseline risks.
Cardiovascular risk factors in Kenya
A population-based survey conducted in Kibera, one of the largest urban slums in Nairobi, Kenya, examined the prevalence of hypertension and related cardiovascular risk factors. The study involved 2,061 adults aged 18 years and above, with a mean age of approximately 33.4 years, and an almost equal distribution of men and women.
The age-standardised prevalence of hypertension was found to be 22.8 per cent, while the crude prevalence was about 12.6 per cent. Additionally, a significant 59.3 per cent of participants were classified as pre-hypertensive, indicating a large population at risk of developing full-blown hypertension.
Despite this high prevalence, only about 20 per cent of those with hypertension were aware of their condition. Among those who were on treatment, just under half had their blood pressure under control.
The study assessed various lifestyle and clinical risk factors. Though nearly 80 per cent of participants reported high physical activity, mainly through walking or work, obesity and central obesity were still prevalent, particularly among women.
Over a third of women were overweight or obese, and around 40 per cent had central obesity. Other significant risk factors identified included high blood sugar levels, diabetes, harmful alcohol use (reported in over 50 per cent of participants), and smoking, which was present in about 10-13 per cent of respondents.
A key insight from the study was that very few individuals had ever had their blood pressure checked, and even fewer had received any health education or counselling on lifestyle-related risk reduction. Obesity, age, and diabetes were found to be independently associated with a higher likelihood of hypertension.
The 2015 WHO STEPwise Survey assessed cardiovascular health among adults and found that approximately 28.6 per cent of Kenyans had hypertension. Awareness levels were low, with only about 29.4 per cent of hypertensive individuals knowing they had the condition.
Even fewer were on treatment (about 6.5 per cent), and of those, only 12.5 per cent had their blood pressure under control. The study also found that the prevalence of hypertension rose sharply with age, from around 17.7 per cent in people aged 18-29 to over 58 per cent among those aged 60-69. This highlights the importance of early detection and lifelong risk monitoring.
Another national-level study evaluating Ideal Cardiovascular Health (iCVH) using factors like BMI, blood pressure, blood sugar, cholesterol, physical activity, diet, and smoking status found that only 1.2 per cent of Kenyan adults achieved the maximum CVH score.
About 45.6 per cent met the minimum ideal health criteria, indicating substantial gaps in preventive care. Risk scores were worse in older adults, urban residents, alcohol users, and those who were overweight or obese.
Preventive care
A 2023 study in Vihiga County, a rural part of western Kenya, revealed an even higher burden. Over 56 per cent of adults were hypertensive, and many also had high abdominal fat, low HDL cholesterol (especially among women), low levels of physical activity, and poor diets. This challenges the common perception that rural populations are automatically healthier due to more physically active lifestyles. In reality, many were not meeting key cardiovascular health targets.
Globally, studies support similar findings. In sub-Saharan Africa, countries like Malawi, Tanzania, and rural South Africa have shown moderate rates of ideal cardiovascular health, while others, such as Benin, report much lower levels.
Research estimates that controlling major risk factors like high blood pressure, obesity, poor diet, and smoking could reduce the risk of heart attacks, strokes, and other cardiovascular conditions by 30 to 80 per cent, depending on the risk factor and population.
If these known and modifiable risk factors are effectively controlled through screening, lifestyle change, medication, and public awareness, Kenya and other African countries can significantly reduce the growing burden of cardiovascular diseases. Investing in prevention, especially in underserved areas like informal settlements and rural counties, is critical to turning this data into lasting health improvements.
According to the Kenya National Bureau of Statistics (KNBS), cardiovascular diseases accounted for 6.6 per cent of all registered deaths in 2024, making them the third leading cause of death in the country. Deaths from non-communicable diseases (NCDs) rose significantly, comprising 61.7 per cent of all health facility-registered deaths, up from 52.4 per cent in 2023.
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