A study conducted by researchers from the Indian Institute of Technology (IIT) Madras has identified the most significant risk factors for cardiovascular disease in adults aged 45 years and above in India. Cardiovascular disease is a term used to describe a disease of the heart or blood vessels, and is characterised by the reduction of blood flow to the heart, brain or body.
All about cardiovascular diseases
According to the World Health Organization (WHO), cardiovascular diseases include coronary heart disease (disease of the blood vessels supplying the heart muscle), cerebrovascular disease (disease of the blood vessels supplying the brain), deep vein thrombosis (blood clots in the legs), pulmonary embolism (the disease in which blood clots in the leg veins dislodge and move to the heart and lungs), peripheral arterial disease (disease of the blood vessels supplying the arms and legs), rheumatic arterial disease (disease in which the heart muscle and heart valves are damaged due to rheumatic fever caused by streptococcal bacteria), and congenital heart disease (disease in which malformations of the heart structure from birth affect the normal development and functioning of the heart).
The leading cause of death globally, cardiovascular diseases represented 32 per cent of global deaths in 2019, with 85 per cent of these deaths being caused by heart attack and stroke.
Heart attack falls under the category of coronary artery disease, and stroke falls under cerebrovascular disease.
Heart attacks and strokes are mostly acute events caused by a blockage that prevents blood from flowing to the heart or brain, as a result of a build-up of fatty deposits on the inner walls of the blood vessels that supply the heart or brain, respectively. Bleeding from a blood vessel in the brain or from clots can result in strokes.
Hypertension is a form of peripheral arterial disease.
How the study was conducted
In order to find the predominant risk factors for cardiovascular disease, IIT Mandi researchers analysed data from over 59,000 individuals aged 45 years and above in both rural and urban India. The study describing the findings was recently published in the journal Current Problems in Cardiology.
As part of the study, the researchers estimated the exclusive effects of various risk factors of cardiovascular disease among 59,073 adults aged 45 years and above. The researchers used data from the Longitudinal Ageing Study in India (LASI), a nationally representative survey of over 73,000 older adults aged 45 and above across all states and union territories of India. After filtering the data, the researchers included 59,073 adults aged 45 years and above.
What are the risk factor groups and independent risk factors of cardiovascular disease?
The study focused on the different components of cardiovascular disease, including heart disease, stroke and hypertension. Risk factor groups such as physiological, environmental, behavioural and genetic risk factors positively and significantly impact cardiovascular diseases, the study said.
Independent risk factors include obesity, cholesterol, alcohol consumption, family history, depression, and diabetes, among others.
How environmental risk factors affect cardiovascular health
According to the study, environmental exposure is a significant risk factor for the occurrence and progression of cardiovascular disease in older adults in India, because a majority of the population of India resides in rural areas and uses unclean fuel for cooking, leading to indoor air pollution due to harmful gases emitted from the burning of those fuels. These fuels include biomass-based fuels such as wood, diesel and kerosene which are used for indoor cooking or heating purposes. The exposure to air pollutants produced by the burning of these fuels increases the risk of cardiovascular-related death. In the case of older adults, the severity of these risk factors intensifies. Passive smoking, or second-hand smoke exposure, also has a devastating impact on cardiovascular health.
Examples of behavioural and genetic risk factors
Behavioural risk factors such as physical inactivity, smoking tobacco, and the use of alcohol have a detrimental effect on the cardiovascular health of people.
Family history is a genetic risk factor for cardiovascular disease.
Why are physiological risk factors for cardiovascular disease so prevalent?
Physiological risk factors for cardiovascular disease include low high density lipoprotein (HDL) cholesterol, unhealthy food, high systolic blood pressure, obesity, poor nutritional status, depression and age, among others. The reasons why these physiological risk factors are prevalent include excessive consumption of fast food, urbanization, and sedentary lifestyle.
Independent risk factor that has the highest impact on hypertension
According to the WHO, an estimated 1.28 billion adults aged 30 to 79 years globally have hypertension. Two-thirds of these adults are living in low- and middle-income countries.
About 46 per cent of adults are estimated to be unaware that they have hypertension, and less than half of adults with the condition are diagnosed and treated.
“As per the results of this study diabetes has the most impact on hypertension. Diabetes and hypertension are both chronic medical conditions that can have a significant impact on a person's health,” Dr Ramna Thakur, Associate Professor, School of Humanities and Social Sciences, IIT Mandi, tells ABP Live.
The reason why diabetes has the most impact on hypertension is that the disease renders the body unable to regulate blood glucose levels properly, leading to a range of complications, Dr Thakur explained. Increased blood sugar levels can damage the nerves and blood vessels of the heart with time, making a person more prone to hypertension and heart diseases. Therefore, it is important to manage blood glucose levels through lifestyle changes and regular monitoring.
“Moreover, studies have shown that adults with diabetes had a higher rate of cardiovascular disease incidence than adults without diabetes, and cardiovascular diseases are a significant contributor to mortality among those with type 2 diabetes mellitus. Elevated blood sugar can damage the heart's nerves and blood vessels with time, making them prone to hypertension and heart diseases. Managing blood glucose levels and blood pressure through lifestyle changes, medication, and regular monitoring can help reduce the risk of complications and improve outcomes for people with these conditions,” says Dr Thakur.
Independent risk factor that has the highest impact on heart disease
Heart disease refers to several types of heart conditions, and can include heart attack, arrhythmia and heart failure. According to Dr Thakur, cholesterol has the highest impact on heart disease. This is because cholesterol results in the formation of fat deposits in blood vessels, leading to increased risk for heart diseases. Since people living in urban areas consume a lot of fast food, and many lead a sedentary lifestyle, they have higher cholesterol levels, and hence, an increased risk of heart disease.
“As per the results of this study, cholesterol has the most impact on heart diseases. If a person has high cholesterol, fat deposits will start forming in their blood vessels, and this could probably be the reason for developing heart diseases and stroke. Fast-food culture has taken over the urban areas, and because these items are high in calories and fat, they have a substantial impact on the development of diabetes and cholesterol. Also, practising a sedentary lifestyle among adults can contribute to higher cholesterol levels. Lack of physical activity can lead to weight gain, which is also associated with higher cholesterol levels,” says Dr Thakur.
Independent risk factor which has the highest impact on stroke
Stroke, also referred to as a brain attack, occurs when blood supply to a part of the brain is stopped, or when a blood vessel in the brain bursts, as a result of which parts of the brain become damaged or die, and can lead to lasting brain damage, long-term disability, or even death.
According to Dr Thakur, cholesterol is the independent risk factor with the highest impact on stroke. This is because high cholesterol levels can result in the formation of fat deposits in the brain blood vessels, and restrict the flow of blood to the brain. Also, high cholesterol levels can increase the risk of blood clots, which can block brain blood vessels.
“As per the results of this study, cholesterol has the most impact on stroke. Fat deposits formed in the blood vessels due to cholesterol could restrict blood flow to the heart and brain in the body leading to heart diseases and stroke. High levels of cholesterol can also increase the risk of blood clots, which can block the blood vessels in the brain and cause a stroke,” says Dr Thakur.
Certain lifestyle factors are responsible for high cholesterol levels in people.
“Lifestyle factors such as a diet rich in saturated and trans fats, lack of physical activity, and smoking can also contribute to the development of high cholesterol levels leading to stroke,” adds Dr Thakur.
Risk factor group with the highest impact on hypertension and heart disease
Physiological risk factors have the highest impact on hypertension and heart disease, according to the study. This is because physiological factors such as the consumption of foods rich in saturated fats, salt and sugar increase the risk of developing diabetes, high cholesterol and obesity, which in turn increase the risk of hypertension and heart disease. Sedentary lifestyle and depression also increase one’s risk of having hypertension and heart disease.
“As per the results of this study, physiological risk factors impact hypertension and heart disease the most. People tend to consume a diet high in saturated fats, salt, and sugar, which increases the risk of developing diabetes, high cholesterol, and obesity. Apart from that, with India's rapid urbanisation and modernisation, many people are leading increasingly sedentary lifestyles, which can contribute to obesity and other health problems. Studies have also shown that depressive patients have more chances of developing cardiovascular diseases like hypertension and heart diseases as compared to non-depressive patients, and therefore the mortality rate is also on a rising scale,” says Dr Thakur.
Risk factor group with the highest impact on stroke
Genetic risk factors, followed by physiological risk factors, have the greatest impact on stroke, according to the study. This is because certain genetic traits can increase one’s likelihood of developing conditions associated with stroke risk.
“As per the results of this study, genetic risk factors followed by physiological risk factors have the highest impact on stroke. Family history is a risk factor for stroke because certain genetic traits can increase the likelihood of developing conditions that are associated with stroke risk,” says Dr Thakur.
When these genetic risk factors are combined with physiological factors such as high blood pressure, high cholesterol or diabetes, the probability of getting a stroke increases. Certain genetic variants can pass on these physiological risk factors from parents to offspring.
“When a person inherits genes that cause CVDs and risk factors like high blood pressure, diabetes or high cholesterol, all of which are major risk factors for stroke, the probability that they get a stroke also rises. And genetic variants can pass on these risk factors from parents to children, ultimately increasing the likelihood of getting a stroke. It coexists with other risk factors for stroke, which are mentioned above. Together, these risk factors can increase the risk of a stroke even further,” adds Dr Thakur.
How can different risk factors for cardiovascular diseases be avoided?
People can control the environmental risk factors for heart disease by reducing indoor air pollution, using cleaner technology such as liquified petroleum gas, solar energy and biogas, and maintaining cleanliness in the house.
Overall, physiological risk factors have the highest impact on the cardiovascular health of older adults compared to other factors. Therefore, middle-aged and elderly people should perform light to moderate physical activity. People should quit smoking, consume a diet rich in green-leafy vegetables, fruits, grains and pulses, avoid eating junk food, and drink plenty of water, in order to reduce the risk of cardiovascular disease.