Preventing and Predicting Diseases. Promoting Health.
Medicine in the 21st century will focus on each individual. It will become proactive in nature. It will increasingly focus on prevention and addressing underlying mechanisms rather than only disease treatment. Modern research and medicine provides deeper insights into disease mechanisms, opens diagnostic windows for viewing health and disease for the individual and generates metrics for assessing wellness.
Preventive medicine aims to be able to detect and treat perturbations in healthy individuals long before disease symptoms appear, thus optimizing the wellness of individuals and avoiding disease. P4 (Preventive, Predictive, Personalized and Participatory) represents a move away from models of reacting to illness to prevention and maintaining health.
Preventive medicine consists of measures taken for disease prevention and health promotion, as opposed to just treatment of symptoms and diseases. Just as health encompasses a variety of physical and mental states, so do disease and disability, which are affected by lifestyle, environmental factors, and genetic predisposition. Health, disease, and disability are dynamic processes (‘health continuum’) which begin before symptoms occur and individuals realize they are affected. Disease prevention relies on anticipatory actions that can be categorized as primary, secondary, and tertiary prevention.
CHRONIC DISEASES - THE LEADING CAUSE OF DEATH AND DISABILITY
Each year, millions of people die of preventable deaths. A 2004 study showed that about half of all deaths in the United States in 2000 were due to preventable behaviors and exposures. Leading causes include lifestyle-related chronic diseases such as cardiovascular disease, chronic respiratory disease, diabetes, and also certain infectious diseases. It is estimated that 400,000 people die each year in the United States due to poor diet and a sedentary lifestyle. According to estimates made by the World Health Organization (WHO), about 55 million people died worldwide in 2011, two thirds of this group from non-communicable (lifestyle-related chronic) diseases, including cancer, diabetes, and chronic cardiovascular and lung diseases. This is an increase from the year 2000, during which 60% of deaths were attributed to these diseases.
Preventive medicine is especially important given the continuing worldwide rise in the prevalence of lifestyle-related chronic diseases as well as an aging population.
AT THE INTERSECTION OF CLINICAL MEDICINE AND PUBLIC HEALTH
There are many approaches for prevention of disease. It is recommended that adults and children visit their doctor or a preventive medicine specialist for regular check-ups, even if they feel healthy, to perform disease screening, identify risk factors for disease, discuss tips for a healthy lifestyle and stay up to date with immunizations and boosters.
Preventive Medicine focuses on the health of individuals, communities, and populations. Its goal is to protect, promote, and maintain health and well-being and to prevent disease, disability, and death. Preventive medicine specialists are licensed medical doctors (MD), who possess core competencies in biostatistics, epidemiology, environmental and occupational medicine, planning and evaluation of health services, management of health care organizations, research into causes of disease and injury in population groups, and the practice of prevention in clinical medicine. They apply knowledge and skills gained from the medical, social, economic, and behavioral sciences.
LEADING CAUSES OF PREVENTABLE DEATH AND ILLNESS
The leading causes of preventable death worldwide share similar trends to the United States. There are a few differences between the two, such as malnutrition, pollution, and unsafe sanitation, that reflect health disparities between the developing and developed world.
|Cause||Deaths caused (millions per year)|
|Sexually transmitted infections||3.0|
|Overweight and obesity||2.5|
|Indoor air pollution from solid fuels||1.8|
|Unsafe water and poor sanitation||1.6|
The leading cause of death in the United States was tobacco. However, poor diet and lack of exercise may soon surpass tobacco as a leading cause of death. These behaviors are modifiable and public health and prevention efforts could make a difference to reduce these deaths.
|Cause||Deaths caused||% of all deaths|
|Poor diet and physical inactivity||400,000||16.6|
|Sexually transmitted infections||20,000||0.8|
LEVELS OF PREVENTION
Preventive healthcare strategies are typically described as taking place at the primary, secondary, and tertiary prevention levels. In the 1940s, Hugh R. Leavell and E. Gurney Clark coined the term primary prevention. They worked at the Harvard and Columbia University Schools of Public Health, respectively, and later expanded the levels to include secondary and tertiary prevention. Goldston (1987) notes that these levels might be better described as “prevention, treatment, and rehabilitation” though the terms primary, secondary, and tertiary prevention are still commonly in use today.
|Primary prevention||Methods to avoid occurrence of disease either through eliminating disease agents or increasing resistance to disease. Examples include immunization against disease, maintaining a healthy diet and exercise regimen, and avoiding smoking.|
|Secondary prevention||Methods to detect and address an existing disease prior to the appearance of symptoms. Examples include treatment of hypertension (a risk factor for many cardiovascular diseases), cancer screenings|
|Tertiary prevention||Methods to reduce negative impact of symptomatic disease, such as disability or death, through rehabilitation and treatment. Examples include surgical procedures that halt the spread or progression of disease|
Primary prevention consists of “health promotion” and “specific protection.” Health promotion activities are non-clinical life choices, for example, eating nutritious meals and exercising daily, that both prevent disease and create a sense of overall well-being. Preventing disease and creating overall well-being, prolongs our life expectancy.Health-promotional activities do not target a specific disease or condition but rather promote health and well-being on a very general level. On the other hand, specific protection targets a type or group of diseases and complements the goals of health promotion. In the case of a sexually transmitted disease such as syphilis health promotion activities would include avoiding microorganisms by maintaining personal hygiene, routine check-up appointments with the doctor, general sex education, etc. whereas specific protective measures would be using prophylactics (such as condoms) during sex and avoiding sexual promiscuity.
Food is very much the most basic tool in preventive health care. The 2011 National Health Interview Survey performed by the Centers for Disease Control was the first national survey to include questions about ability to pay for food. Difficulty with paying for food, medicine, or both is a problem facing 1 out of 3 Americans. If better food options were available through food banks, soup kitchens, and other resources for low-income people, obesity and the chronic conditions that come along with it would be better controlled. A “food desert” is an area with restricted access to healthy foods due to a lack of supermarkets within a reasonable distance. These are often low-income neighborhoods with the majority of residents lacking transportation. There have been several grassroots movements in the past 20 years to encourage urban gardening, such as the GreenThumb organization in New York City. Urban gardening uses vacant lots to grow food for a neighborhood and is cultivated by the local residents. Mobile fresh markets are another resource for residents in a “food desert”, which are specially outfitted buses bringing affordable fresh fruits and vegetables to low-income neighborhoods. These programs often hold educational events as well such as cooking and nutrition guidance. Programs such as these are helping to provide healthy, affordable foods to the people who need them the most.
Scientific advancements in genetics have significantly contributed to the knowledge of hereditary diseases and have facilitated great progress in specific protective measures in individuals who are carriers of a disease gene or have an increased predisposition to a specific disease. Genetic testing has allowed physicians to make quicker and more accurate diagnoses and has allowed for tailored treatments or personalized medicine. Similarly, specific protective measures such as water purification, sewage treatment, and the development of personal hygienic routines (such as regular hand-washing) became mainstream upon the discovery of infectious disease agents such as bacteria. These discoveries have been instrumental in decreasing the rates of communicable diseases that are often spread in unsanitary conditions.
Finally, a separate category of health promotion par excellence has been propounded. It is based on the ‘new knowledge’ in molecular biology; in particular, on epigenetic knowledge, which points to how much affective – as well as physical – environment during foetal and newborn life may determine each and every aspect of adult health;.This new way of promoting health is commonly called primal prevention. It consists mainly in providing future parents with pertinent, unbiased information on primal health and supporting them during their child’s primal period of life (i.e., “from conception to first anniversary” according to definition by the Primal Health Research Centre, London). This includes adequate parental leave – ideally for both parents – with kin caregiving and financial help where needed.
Secondary prevention deals with latent diseases and attempts to prevent an asymptomatic disease from progressing to symptomatic disease. Certain diseases can be classified as primary or secondary. This depends on definitions of what constitutes a disease, though, in general, primary prevention addresses the root cause of a disease or injury whereas secondary prevention aims to detect and treat a disease early on. Secondary prevention consists of “early diagnosis and prompt treatment” to contain the disease and prevent its spread to other individuals, and “disability limitation” to prevent potential future complications and disabilities from the disease. For example, early diagnosis and prompt treatment for a syphilis patient would include a course of antibiotics to destroy the pathogen and screening and treatment of any infants born to syphilitic mothers. Disability limitation for syphilitic patients includes continued check-ups on the heart, cerebrospinal fluid, and central nervous system of patients to curb any damaging effects such as blindness or paralysis.
Finally, tertiary prevention attempts to reduce the damage caused by symptomatic disease by focusing on mental, physical, and social rehabilitation. Unlike secondary prevention, which aims to prevent disability, the objective of tertiary prevention is to maximize the remaining capabilities and functions of an already disabled patient. Goals of tertiary prevention include: preventing pain and damage, halting progression and complications from disease, and restoring the health and functions of the individuals affected by disease. For syphilitic patients, rehabilitation includes measures to prevent complete disability from the disease, such as implementing work-place adjustments for the blind and paralyzed or providing counseling to restore normal daily functions to the greatest extent possible.
Screening, in medicine, is a strategy used in a population to identify the possible presence of an as-yet-undiagnosed disease in individuals without signs or symptoms. This can include individuals with pre-symptomatic or unrecognized symptomatic disease. As such, screening tests are somewhat unique in that they are performed on persons apparently in good health. Screening interventions are designed to identify disease in a community early, thus enabling earlier intervention and management in the hope to reduce mortality and suffering from a disease. Although screening may lead to an earlier diagnosis, not all screening tests have been shown to benefit the person being screened; overdiagnosis, misdiagnosis, and creating a false sense of security are some potential adverse effects of screening. For these reasons, a test used in a screening program, especially for a disease with low incidence, must have good sensitivity in addition to acceptable specificity. Several types of screening exist: universal screening involves screening of all individuals in a certain category (for example, all children of a certain age). Case finding involves screening a smaller group of people based on the presence of risk factors (for example, because a family member has been diagnosed with a hereditary disease). Screening interventions are not designed to be diagnostic, and often have significant rates of both false positive and false negative results.
Some common disease screenings include checking for hypertension (high blood pressure), hyperglycemia (high blood sugar, a risk factor for diabetes mellitus),hypercholesterolemia (high blood cholesterol), screening for colon cancer, depression, HIV and other common types of sexually transmitted disease such as chlamydia, syphilis, andgonorrhea, mammography (to screen for breast cancer), colorectal cancer screening, a pap test (to check for cervical cancer), and screening for osteoporosis. Genetic testing can also be performed to screen for mutations that cause genetic disorders or predisposition to certain diseases such as breast or ovarian cancer. However, these measures are not affordable for every individual and the cost effectiveness of preventive healthcare is still a topic of debate.
THE ROLE OF NEW TECHNOLOGY
Most of the technology will be implemented to empower the individual to improve their overall healthcare in a proactive rather than a reactive fashion. As important as the technological advances are, the policy issues that drive the implementation of technology will be the key factors that determine the future procedures, distribution, availability, etc of healthcare. The following will focus on the technologic contribution to preventive medicine.