A noncommunicable disease (NCD) is a disease that is not ordinarily transmitted from one person to another. NCDs commonly develop through interacting genetic, physiological, environmental, and behavioral factors and often persist for long periods. The World Health Organization (WHO) identifies cardiovascular diseases, cancers, chronic respiratory diseases, and diabetes as the principal groups addressed by global NCD programs. Together, they constitute a major focus of public health. (who.int)
Definition and scope
“Noncommunicable” describes transmission, whereas “chronic” describes duration. Although the terms frequently overlap, they are not identical: an infectious disease can persist for many years. Moreover, classification as an NCD does not mean that infection can never contribute to its development. Certain infectious agents cause or increase the risk of cancers, even though the resulting cancer is not ordinarily transmitted between people. (iris.who.int)
The four principal groups used in international NCD monitoring are:
- Cardiovascular diseases, including heart attacks and stroke.
- Cancer, comprising numerous malignant diseases.
- Chronic respiratory diseases, including chronic obstructive pulmonary disease and asthma.
- Diabetes mellitus, including conditions requiring continuing management of blood glucose.
These groups are priorities for surveillance and intervention, rather than an exhaustive definition of every noncommunicable condition. WHO’s essential-interventions framework organizes primary-care services around these major disease groups. (who.int)
Causes and risk factors
NCDs have diverse causes; no single biological mechanism explains the entire category. Genetic susceptibility, physiological processes, environmental exposure, and behavior interact in disease-specific ways. Major shared risk factors include tobacco use, physical inactivity, harmful alcohol use, unhealthy diets, and air pollution. Elevated blood pressure, overweight or obesity, raised blood glucose, and abnormal blood lipids are important metabolic risk factors. NCDs affect children and younger adults as well as older people. (who.int)
A risk factor increases the likelihood of disease but does not necessarily explain why a particular individual becomes ill. Research in epidemiology identifies patterns across populations; an observed association alone does not establish causation. For cancer, evidence from multiple studies and plausible biological mechanisms helps distinguish causal relationships from associations produced by chance or other factors. Age and family history are examples of risk factors that cannot simply be removed through behavioral change. (cancer.gov)
Infections illustrate the overlap between disease categories. Persistent hepatitis B or C infection can cause liver cancer, while high-risk human papillomavirus infection causes nearly all cervical cancers. Some infectious agents alter cellular signaling; others weaken the immune system or produce chronic inflammation. These pathways connect communicable exposures with noncommunicable outcomes. (cancer.gov)
Global burden and measurement
WHO estimates indicate that NCDs caused at least 43 million deaths in 2021, approximately 75% of deaths excluding those related to the pandemic. About 18 million NCD deaths occurred before age 70. Low- and middle-income countries accounted for approximately 73% of all NCD deaths and 82% of those occurring before age 70. These figures describe a specified historical year, not a real-time annual count. (who.int)
International monitoring distinguishes total deaths from premature mortality. Sustainable Development Goal indicator 3.4.1 measures the probability of dying between exact ages 30 and 70 from cardiovascular disease, cancer, diabetes, or chronic respiratory disease. It assumes current age-specific mortality rates and excludes competing causes of death. Consequently, it differs from simply counting all NCD deaths among people younger than 70. (data.who.int)
Social and economic determinants
Exposure and access to care are shaped by social determinants of health: the conditions in which people are born, grow, live, work, and age. Housing, education, employment, social protection, and access to resources influence opportunities for health. These conditions help explain why NCD risk cannot be understood solely as the result of individual choices. (who.int)
Poverty and NCDs are closely connected. Socially disadvantaged populations may face limited access to health services, while continuing healthcare expenditure can place pressure on household finances. WHO identifies these relationships as obstacles to poverty reduction and sustainable development. (who.int)
Prevention, care, and policy
Population-level NCD prevention includes tobacco and alcohol taxation, advertising restrictions, food-reformulation policies, and programs supporting physical activity. WHO’s “best buys” framework identifies cost-effective interventions alongside other policy options. Such measures operate through regulation, commercial environments, and community infrastructure rather than exclusively through clinical encounters. (who.int)
Clinical responses include detection, diagnosis, treatment, and palliative care. WHO’s Package of Essential Noncommunicable Disease Interventions supports integrated delivery through primary health care, particularly where resources are limited. Its purpose is to improve service coverage and organize feasible, cost-effective care within the health system. (who.int)
SDG target 3.4 sets a 2030 objective of reducing premature NCD mortality by one third through prevention and treatment. WHO’s 2025 NCD Progress Monitor assesses national capacity, policy implementation, and health-system responses, providing a mechanism for tracking government commitments and implementation across countries. (who.int)