A non-communicable disease, or NCD, is a medical condition or disease which is non-infectious. NCDs are diseases of long duration and generally slow progression. They include heart disease, stroke, cancer, asthma, diabetes, chronic kidney disease, osteoporosis, Alzheimer's disease, cataracts, and more. While often referred to as "chronic diseases", NCDs are distinguished by their non-infectious cause. In contrast, some chronic diseases such as HIV/AIDS, while also lasting medical conditions, are caused by transmissible infections. They are similar in that they also require chronic care management.
The World Health Organization (WHO) reports NCDs to be by far the leading cause of mortality in the world, representing over 60% of all deaths. Out of the 35 million people who died from NCDs in 2005, half were under age 70 and half were women.[1] Of the 57 million global deaths in 2008, 36 million were due to NCDs [2]. That is approximately 63% of total deaths worldwide. Risk factors such as a person's background, lifestyle and environment are known to increase the likelihood of certain NCDs. Every year, at least 5 million people die because of tobacco use and about 2.8 million die from being overweight. High cholesterol accounts for roughly 2.6 million deaths and 7.5 million die because of high blood pressure. By 2030, deaths due to chronic NCDs are expected to increase to 52 million per year while deaths caused by infectious diseases, maternal and perinatal conditions and nutritional deficiencies are expected to decline by 7 million per year during the same period.[3]
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Risk factors such as a person's background, lifestyle and environment are known to increase the likelihood of certain non-communicable diseases. They include age, sex, genetics, exposure to air pollution, and behaviours such as smoking, unhealthy diet and physical inactivity which can lead to hypertension and obesity, in turn leading to increased risk of many NCDs.[4] Most NCDs are considered preventable because they are caused by modifiable risk factors.
The WHO's World Health Report 2002 identified five important risk factors for non-communicable disease in the top ten leading risks to health. These are raised blood pressure, raised cholesterol, tobacco use, alcohol consumption, and overweight.[5] Other factors associated with higher risk of NCDs include a person's economic and social conditions, also known as the "social determinants of health."
It has been estimated that if the primary risk factors were eliminated, 80% of the cases of heart disease, stroke and type 2 diabetes and 40% of cancers could be prevented. Interventions targeting the main risk factors could have a significant impact on reducing the burden of disease worldwide. Efforts focused on better diet and increased physical activity have been shown to control the prevalence of NCDs.[3]
NCDs include many environmental diseases, covering a broad category of avoidable and unavoidable human health conditions caused by external factors, such as sunlight, food, pollution, and lifestyle choices. The diseases of affluence are non-infectious diseases with environmental causes. Examples include:
Genetic disorders are caused by errors in genetic information that produce diseases in the affected people. These errors may include:
Cystic fibrosis is an example of an inherited disease that is caused by a mutation on a gene. The faulty gene impairs the normal movement of sodium chloride in and out of cells, which causes the mucus-secreting organs to produce abnormally thick mucus. The gene is recessive, meaning that a person must have two copies of the faulty gene for them to develop the disease. Cystic fibrosis affects the respiratory, digestive and reproductive systems, as well as the sweat glands. The mucus secreted is very thick and blocks passageways in the lungs and digestive tracts. This mucus causes problems with breathing and with the digestion and absorption of nutrients.
Historically, many NCDs were associated with economic development and so-called "diseases of the rich".[6] However, today an estimated 80% of the four main types of NCDs - cardiovascular diseases, cancers, chronic respiratory diseases and diabetes - occur in low- and middle-income countries.[7] The prevention and control of NCDs is becoming increasingly important on the global health agenda.
The World Health Organization is the specialized agency of the United Nations (UN) that acts as coordinating authority on international public health issues, including NCDs. In May 2008, the 193 Member States of the WHO approved a six-year plan to address non-communicable diseases, especially the rapidly increasing burden in low- and middle-income countries.[7] The plan calls for raising the priority given to NCDs in international development work.[8]
During the 64th session of the United Nations General Assembly in 2010, a resolution was passed to call for a high-level meeting of the General Assembly on the prevention and treatment NCDs with the participation of heads of state and government. The resolution also encouraged UN Member States to address the issue of non-communicable diseases at the 2010 Review Summit for the Millennium Development Goals.[9]
In September 2011, the UN is hosting its first General Assembly Special Summit on the issue of NCDs.[10] Noting that NCDs are the cause of some 35 million deaths each year, the international community is being increasingly called to take important measures for the prevention and control of non-communicable diseases, and mitigate their impacts on the world population especially on women, who are usually the primary caregivers.
In order to better coordinate efforts around the globe, in 2009 the WHO announced the launch of the Global Non-communicable Disease Network (NCDnet).[11] NCDnet will consist of leading health organizations and experts from around the world in order to fight against diseases such as cancer, cardiovascular disease, and diabetes. Ala Alwan, assistant director-general for Non-communicable Diseases and Mental Health at the WHO, said: "integrating the prevention of non-communicable diseases and injuries into the national and global development agendas is not only achievable but also a priority for developing countries."[12]
The NCD Alliance is a global partnership founded in May 2009 by four international federations representing cardiovascular disease, diabetes, cancer, and chronic respiratory disease. The NCD Alliance brings together roughly 900 national member associations to fight non-communicable disease. Long term aims of the Alliance include[13]:
Previously, chronic NCDs were considered a problem limited mostly to high income countries, while infectious diseases seemed to affect low income countries. The burden of disease attributed to NCDs has been estimated at 85% in industrialized nations, 70% in middle income nations, and nearly 50% in countries with the lowest national incomes.[3] In 2008, chronic NCDs accounted for more than 60% (over 35 million) of the 57 million deaths worldwide. Given the global population distribution, almost 80% of deaths due to chronic NCDs worldwide now occur in low and middle income countries, while only 20% occur in higher income countries.
National economies are reportedly suffering significant losses because of premature deaths or inability to work resulting from heart disease, stroke and diabetes. For instance, China is expected to lose roughly $558 billion in national income between 2005 and 2015 due to early deaths. In 2005, heart disease, stroke and diabetes caused an estimated loss in international dollars of national income of 9 billion in India and 3 billion in Brazil.[3]
The burden of chronic NCDs including mental health conditions is felt in workplaces around the world, notably due to elevated levels of absenteeism, or absence from work because of illness, and presenteeism, or productivity lost from staff coming to work and performing below normal standards due to poor health. For example, the United Kingdom experienced a loss of about 175 million days in 2006 to absence from illness among a working population of 37.7 million people. The estimated cost of absences due to illness was over 20 billion pounds in the same year.[14] The cost due to presenteeism is likely even larger, although methods of analyzing the economic impacts of presenteeism are still being developed. Methods for analyzing the distinct workplace impacts of NCDs versus other types of health conditions are also still being developed.
The vast majority of cancer risk factors are environmental or lifestyle-related, thus cancer is largely a preventable NCD.[15] Greater than 30% of cancer is preventable via avoiding risk factors including: tobacco, being overweight or obesity, low fruit and vegetable intake, physical inactivity, alcohol, sexually transmitted infections, and air pollution.[16]
The first studies on cardiovascular health were performed in 1949 by Jerry Morris using occupational health data and were published in 1958.[17] The causes, prevention, and/or treatment of all forms of cardiovascular disease remain active fields of biomedical research, with hundreds of scientific studies being published on a weekly basis. A trend has emerged, particularly in the early 2000s, in which numerous studies have revealed a link between fast food and an increase in heart disease. These studies include those conducted by the Ryan Mackey Memorial Research Institute, Harvard University and the Sydney Center for Cardiovascular Health. Many major fast food chains, particularly McDonald's, have protested the methods used in these studies and have responded with healthier menu options.
A fairly recent emphasis is on the link between low-grade inflammation that hallmarks atherosclerosis and its possible interventions. C-reactive protein (CRP) is an common inflammatory marker that has been found to be present in increased levels in patients at risk for cardiovascular disease.[18] Also osteoprotegerin which involved with regulation of a key inflammatory transcription factor called NF-κB has been found to be a risk factor of cardiovascular disease and mortality.[19][20]
Diabetes mellitus is an NCD which is largely preventable and manageable but difficult to cure. Management concentrates on keeping blood sugar levels as close to normal ("euglycemia") as possible without presenting undue patient danger. This can usually be with close dietary management, exercise, and use of appropriate medications (insulin only in the case of type 1 diabetes mellitus. Oral medications may be used in the case of type 2 diabetes, as well as insulin).
Patient education, understanding, and participation is vital since the complications of diabetes are far less common and less severe in people who have well-managed blood sugar levels.[21][22] Wider health problems may accelerate the deleterious effects of diabetes. These include smoking, elevated cholesterol levels, obesity, high blood pressure, and lack of regular exercise.
Although chronic kidney disease (CKD) is not currently identified as one of WHO's main targets for global NCD control, there is compelling evidence that CKD is not only common, harmful and treatable but also a major contributing factor to the incidence and outcomes of at least three of the diseases targeted by WHO (diabetes, hypertension and CVD).[23] CKD strongly predisposes to hypertension and CVD; diabetes, hypertension and CVD are all major causes of CKD; and major risk factors for diabetes, hypertension and CVD (such as obesity and smoking) also cause or exacerbate CKD. In addition, among people with diabetes, hypertension, or CVD, the subset who also have CKD are at highest risk of adverse outcomes and high health care costs. Thus, CKD, diabetes and cardiovascular disease are closely associated conditions that often coexist; share common risk factors and treatments; and would benefit from a coordinated global approach to prevention and control.