Research in Diseases, Disorders, and Health Conditions
Chronic Diseases and Organ Systems
Chronic diseases are defined by HHS as conditions that last a year or more and require ongoing medical attention and/or limit activities of daily living. Chronic diseases place a considerable burden on the U.S. health care system, the national economy, and the health and lives of individual patients and their families. Not all chronic diseases are fatal; however, seven of every 10 Americans who die each year—more than 1.7 million people—succumb to a chronic disease.102 Health-damaging behaviors such as drug use (e.g., tobacco, excessive alcohol, or other drug), lack of physical activity, poor eating habits, and obesity, contribute to many chronic diseases, whereas others may result from the long-term effect of early exposure to toxins or other environmental factors, especially in individuals with a higher genetic risk of disease. Some chronic diseases and conditions may affect more than one organ. For example, diabetes can affect the pancreas, heart, kidneys, eyes, and nerve endings in the limbs. People with serious mental illness are more likely to suffer with chronic diseases that are associated with addiction (especially nicotine), obesity (sometimes associated with antipsychotic medication), and poverty (with its attendant poor nutrition and health care), and they may suffer the adverse health consequences earlier. For these reasons, modern medicine requires an integrated understanding of the complex interactions among multiple organs, the nervous system, the circulatory system, the immune system, and the endocrine system.
A shared aspect of many chronic diseases is chronic pain and other disease-associated disabilities that interfere with quality of life. A recent study shows that approximately 100 million American adults—more than the total affected by heart disease, cancer, and diabetes combined—suffer from chronic pain.103 As many as 75 million Americans suffer from two or more concurrent chronic conditions,104 placing them at risk for worse overall health and significant financial burden, including higher prescription drug and total out-of-pocket health care spending.
Thus, research to combat chronic illness involves significant trans-NIH collaboration in addition to the mission-specific work of each IC. NIH supports basic research on both normal and disease states of organ systems to understand the initiation and progression of chronic diseases, as well as translational and clinical research on new biomedical and behavioral strategies to prevent, preempt, diagnose, treat, and cure these diseases. The ultimate goal is to reduce or eliminate morbidity and mortality while improving quality of life for those living with these often debilitating conditions.
This section provides information about NIH’s activities related to a number of major chronic diseases, as well as research on aspects of the function of various organ systems. Additional major chronic diseases are discussed in the sections “Cancer” (cancers of all organs and tissues, including blood), “Neurosciences” (e.g., Parkinson’s disease, Alzheimer’s disease, autism, and epilepsy), “Autoimmune Diseases” (e.g., lupus, multiple sclerosis, rheumatoid arthritis, and inflammatory bowel diseases), and “Infectious Diseases and Biodefense” (e.g., HIV/AIDS and viral hepatitis). Because some people with certain chronic diseases require transplantation to replace a diseased organ or tissue, organ transplantation research and the related issue of establishing immune tolerance to transplanted organs (i.e. ensuring the organ is not rejected by the recipient’s immune system) are highlighted in this section. Research on complementary and alternative medicine (CAM) approaches to combating chronic disease also is discussed. NIH supports research to reduce the pain associated with long-term diseases and to find innovative and effective forms of palliative care to relieve disease symptoms. Some of these efforts were highlighted in the Neuroscienc section.
The prevalence and burden of chronic diseases are substantial. About 133 million Americans—nearly half of adults—live with at least one chronic illness.105 Chronic disease disables or limits activity for almost 12 percent of all adults, including more than one-third of adults ages 65 and older.106 Notably, the percentage of U.S. children and adolescents with a chronic health condition has increased significantly, from 1.8 percent in the 1960s to more than 7 percent in 2004. Furthermore, the increasing prevalence of patients with one or multiple chronic diseases has a significant impact on health care delivery and the economy; more than 75 percent of health care costs are related to treatment of chronic conditions.107
Many chronic diseases that lead to significant disability develop over time and become more prevalent with age (e.g., osteoarthritis, chronic kidney disease, vision loss). Less commonly, chronic disease may manifest from birth as a result of one or more faulty genes (e.g., sickle cell anemia, hemophilia) or at other times during childhood (e.g., allergies, asthma). Some chronic diseases are common in the U.S. population, as in the case of heart disease, which is the leading cause of death, while others are relatively rare, such as cystic fibrosis, which affects approximately 30,000 Americans. Certain chronic diseases and conditions represent growing public health issues, such as the increases in obesity and type 2 diabetes in children and adults.
Many chronic diseases and conditions that are common in the U.S., such as type 2 diabetes, obesity, and heart disease, also have a substantial impact on global morbidity and mortality. By 2015, chronic diseases will be the most common cause of death even in the poorest countries. In 2005, chronic diseases contributed approximately 60 percent of the 58 million total deaths in the world and almost three-quarters of the burden of disease (measured in disability-adjusted life-years108) in those ages 30 or older.109
102Centers for Disease Control and Prevention, Chronic Diseases: The Power to Prevent, the Call to Control. Atlanta, GA, 2009. Available at https://www.cdc.gov/nccdphp/publications/AAG/chronic.htm.
103Committee on Advancing Pain Research and Education, Relieving Pain in America: A Blueprint for Transforming Prevention, Care, Education, and Research. Washington, D.C.: Institute of Medicine, 2011. Available at: https://iom.edu/Reports/2011/Relieving-Pain-in-America-A-Blueprint-for-Transforming-Prevention-Care-Education-Research.aspx .
104Hwang W, et al. Health Affairs. 2001;(20)268–9. PMID: 11816667.
105Centers for Disease Control and Prevention, Chronic Diseases: The Power to Prevent, the Call to Control. Atlanta, GA, 2009. Available at: https://www.cdc.gov/nccdphp/publications/AAG/chronic.htm.
106National Center for Health Statistics. Health, United States, 2008 with Chartbook. Hyattsville, MD, 2009.
107Centers for Disease Control and Prevention, Chronic Diseases: The Power to Prevent, the Call to Control. Atlanta, GA, 2009. Available at: https://www.cdc.gov/nccdphp/publications/AAG/chronic.htm.
108Disability-Adjusted Life Years (DALYs) are years lost due to a disability. DALYs are used to measure the overall burden of a disease.
109Quam L, et al. Lancet. 2006;368(9543):1221–3. PMID: 17027712.
Currently, NIH does not collect the data necessary to provide an aggregate figure for expenditures on chronic diseases and organ systems research. Appendix H provides funding estimates for many of the areas of research associated with chronic diseases and organ systems. Because of overlap among the areas of research listed in the table, and because research on chronic disease and organ systems may account for only a portion of the funding for a given area, the figures in that table cannot be used to provide an aggregate number.
NIH invests significant resources in the study of chronic diseases, and nearly all NIH ICs support research to understand the molecular and cellular mechanisms of human physiology in the health and disease of organ systems. Such research has the potential to lead to new insights and treatments for chronic diseases. The diverse NIH research portfolio broadly encompasses research on the normal physiology of all organ systems in the body; studies of rare and common diseases in both children and adults; development of devices and technologies for disease detection and diagnosis; evaluation of strategies for prevention and treatment that might be based on pharmaceuticals, behavioral modification, surgical techniques, mechanical devices, or other approaches; and translation of research results into real-world applications or resources for the benefit of patients who live with chronic diseases every day. This section highlights key examples of challenges, progress, and emerging opportunities in NIH-supported research on chronic diseases and organ health.