Non communicable diseases (NCDs)

Introduction

Non-communicable diseases (NCDs) encompass a wide range of conditions, including cardiovascular diseases, renal diseases, nervous and mental disorders, musculoskeletal conditions like arthritis and related diseases, chronic non-specific respiratory diseases (such as chronic bronchitis, emphysema, and asthma), permanent consequences of accidents, senility, blindness, cancer, diabetes, obesity, various other metabolic and degenerative diseases, as well as chronic outcomes of communicable diseases. Disorders with unknown causes and progressive courses are often labelled as “degenerative.”

Statement of problem

Non-communicable diseases (NCDs) are a major global health concern, responsible for 36 million of the 57 million deaths worldwide in 2008, accounting for 63% of all deaths. Cardiovascular diseases led to 47.9% of NCD-related deaths, followed by cancers at 21%, chronic respiratory diseases at 11.72%, digestive diseases at 6.1%, diabetes at 3.5%, and other NCDs contributing 9.78%. With the aging population, annual deaths from NCDs are projected to rise significantly to 52 million by 2030. This includes an anticipated increase in cardiovascular disease mortality by 6 million and cancer mortality by 4 million. In low- and middle-income countries, NCDs are expected to account for three times as many disability-adjusted life years (DALYs) and nearly five times as many deaths as communicable diseases, maternal, perinatal, and nutritional conditions combined.

According to the World Health Organization (WHO), as of 2023, NCDs remain a significant global threat, responsible for approximately 74% of all deaths worldwide, with cardiovascular diseases still being the leading cause of death among NCDs. WHO’s latest data shows that in low- and middle-income countries, NCDs continue to outpace infectious diseases, underscoring the need for comprehensive public health strategies to manage this growing burden.

In Nepal, NCDs, including cardiovascular diseases, cancers, chronic respiratory diseases, and diabetes, have become the leading causes of death. In 2016, it was estimated that over 127,000 people died from NCDs, representing 66% of the total national deaths. The burden of NCDs in Nepal has been rising steadily, necessitating urgent action for their prevention and control. Data from the Nepal Burden of Disease shows the proportion of deaths due to NCDs rose from 31.3 per cent in 1990 to a whopping 71.1 per cent in 2019.

Non-communicable disease risk factors

 A large percentage of non-communicable diseases (NCDs) are preventable by addressing key risk factors and underlying metabolic or physiological causes. The influences of these factors on the NCD epidemic are significant.

Tobacco: Nearly 6 million deaths annually are due to tobacco use, including second-hand smoke exposure. Smoking is a leading cause of lung cancer, chronic respiratory diseases, and cardiovascular conditions, with the highest prevalence in lower- and upper-middle-income countries.

Insufficient physical activity: Physical inactivity causes around 3.2 million deaths each year and increases the risk of cardiovascular diseases, cancer, and depression. It is most prevalent in high-income countries, with growing concerns in middle-income nations, particularly among women.

Harmful use of alcohol: Harmful alcohol consumption leads to approximately 2.3 million deaths annually, contributing significantly to cancers, cardiovascular diseases, and liver cirrhosis. Consumption rates are highest in high-income and populous upper-middle-income countries.

Unhealthy diet: Poor diets high in salt, saturated fats, and trans-fatty acids increase the risk of cardiovascular diseases and certain cancers. Unhealthy eating habits are rising rapidly in lower-resource settings, with a notable increase in fat intake in lower-middle-income countries since the 1980s.

Raised blood pressure: Responsible for 7.5 million deaths annually, raised blood pressure is a major risk factor for cardiovascular disease and is prevalent across all income groups.

Overweight and obesity: Overweight and obesity cause at least 2.8 million deaths each year and are linked to increased risks of heart disease, stroke, diabetes, and certain cancers. High rates of obesity are seen in upper-middle and lower-middle-income countries.

Raised cholesterol: With 2.6 million deaths annually, raised cholesterol significantly increases the risk of heart disease and stroke, particularly in high-income countries.

Cancer-associated infections: Around 2 million cancer cases yearly, or 18% of the global burden, are due to infections like HPV and Hepatitis B and C, especially in low-income countries. These infections are largely preventable through vaccination and other measures.

Environmental risk factors: Environmental factors like occupational hazards, air and water pollution, and the possession of destructive weapons contribute to the NCD burden and related injuries.

Modifiable behavioural risk factors

• Tobacco consumption: 7.2 million deaths every year
• Excess salt/sodium intake: 4.1 million deaths
• Insufficient physical activity: 1.6 million deaths
• Alcohol use: More than half of 3.3 million annual deaths attributable to alcohol use are from NCDs
• Obesity
• Raised blood glucose
• High blood pressure
• cholesterol

Non-modifiable risk factors

• Age
• race
• gender
•  genetics

Gaps in natural history

There are significant gaps in understanding the natural history of chronic diseases, which complicates aetiological research. These include the absence of a known agent, multifactorial causation, long latent periods, and indefinite onset, all of which hinder diagnosis, prevention, and research.

Absence of a known agent: While some chronic diseases have known causes (e.g., silica in silicosis), many do not. The lack of a clear causative agent makes diagnosis and specific prevention challenging.

Multifactorial causation: Most chronic diseases result from multiple causes rather than a single one. The concept of “risk factors” is used to describe elements that increase the likelihood of developing chronic conditions, though many risk factors remain unidentified.

Long latent period: Chronic diseases often have long latent periods between exposure to a cause and disease development, making it difficult to link cause and effect. This gap complicates research and early intervention.

Indefinite onset: Chronic diseases typically develop slowly, and distinguishing between healthy and diseased states can be difficult. By the time symptoms manifest, the disease may be well-established and harder to treat.

Prevention

The preventive attack on chronic diseases is based on the knowledge that they are multifactorial in causation, so their prevention demands a complex mix of interventions.  Previously only tertiary prevention seemed possible to prevent or delay the development of further disability or the occurrence of premature death. But, now, with the identification of risk factors, health promotion activities aimed at primary prevention are being increasingly applied in the control of chronic diseases. Some of the interventions that should be under taken immediately to produce accelerated results in terms of lives saved, disease prevented and heavy cost avoided are as follows:

1. Protecting people from tobacco smoke and banning smoking in public places, warning about the dangers of tobacco use, enforcing bans on tobacco advertising, promotion and sponsorships and raising taxes on tobacco;
2. Restricting access to retailed alcohol, enforcing bans on alcohol advertising and raising taxes on alcohol;
3. Reduce salt intake and salt content of food;
4. Replacing trans-fat in food with polyunsaturated fat; and
5. Promoting public awareness about diet and physical activity, including through mass media.

In addition, there are many other cost-effective and low-cost population-wide interventions that can reduce risk factors for NCDs. These include:

• Nicotine dependence treatment;
• Enforcing drink-driving laws;
• Restrictions on marketing of foods and beverages high in salt, fats and sugar;
• Food taxes and subsidies to promote healthy diets.
• Healthy nutrition environments in schools;
• Nutrition information and counselling in health care;
• National physical activity guidelines (school based physical activity programmes for children and work place programmes for physical activity and healthy diets).
• There also are population-wide interventions that focus on cancer prevention, like vaccination against Hepatitis B, major cause of liver cancer. Vaccination against human papillomavirus (HPV), the main cause of cervical cancer, is also recommended.

Sources: Park, K. (2021). Park’s textbook of preventive and social medicine (26th ed.). Bhanot Publishers.

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