Preventive medicine

DEFINITION: The medical field that seeks to protect, promote, and maintain the health and well-being of individuals and defined populations and to prevent disease, disability, and premature death.

Overview

Modern preventive medicine is considered to exist at three levels within the healthcare community. The initial level, primary prevention, aims to maintain health by removing the causes of, or protecting the community or individual from, agents of disease and injury. Although traditionally these activities focused on the prevention of infection, they have been expanded to also include improvement in the environment and behavioral changes to reduce risk factors that contribute to chronic disease and injury. An example of primary prevention is immunization programs for children. To reduce the risk of heart attack, one should refrain from smoking, be active, and reduce fat intake—all wise primary prevention actions. Halting the loss of atmospheric ozone, reducing air and water pollution, and developing environmentally friendly technologies form another class of prevention actions.

Secondary prevention seeks to detect and correct adverse health conditions before they manifest as disease by reversing, halting, or retarding the disease process. One frequently used secondary prevention technique is health screening. Examples include screening services for hypertension (high blood pressure), diabetes, prostate cancer, and glaucoma. In industry, routine hearing tests are used as a tool to prevent noise-induced hearing loss among the workforce. Once a potential health problem is identified, clinical preventive medicine techniques can be instituted to reverse the condition or prevent further progression.

Tertiary prevention seeks to minimize the adverse effects of disease and disability. Coronary bypass surgery, vocational rehabilitation, and treatment of an incapacitating mental illness are examples.

Specialists in the field of preventive medicine typically focus their efforts on the paradigms of primary and secondary prevention. In epidemiological terms, primary prevention results in a reduction of the incidence of a disease (the new cases occurring over time). Secondary prevention, on the other hand, results in a reduction of the prevalence of a disease (the number of people suffering from a particular illness at a given point in time).

Most physicians provide some degree of preventive medicine services. Pediatricians are practicing preventive medicine when they conduct “well-baby evaluations” and ensure that immunizations are current. Family medicine specialists are providing such services when they perform Pap testing or order mammograms. When the cessation of smoking is discussed and internists prescribe nicotine-patch regimens, that too is preventive medicine.

In the United States, physicians who specialize in preventive medicine are certified by the American Board of Preventive Medicine, which recognizes three subspecialties: public health and general preventive medicine, occupational medicine, and aerospace medicine. Some general preventive medicine specialists use epidemiological methods to design and develop prevention programs, which may feature a single intervention or may include a multitude or matrix of screening technologies and interventions. Others provide services in a clinical setting by ordering a history and physical examination, which may include age- and gender-specific screening tests. The general preventive medicine specialist can then counsel the patient on lifestyle alterations recommended to preserve or improve health.

Practicing in industry or private clinic settings, specialists in occupational medicine are concerned about preventing injury and illness as a result of the physical, biological, and chemical hazards that are present in the workplace. Should workers be injured or become ill as a result of their employment, the occupational medicine physician manages their treatment, rehabilitation, and return to work. Some areas of preventive practice are highly specialized. For instance, aerospace medicine focuses on unique challenges in the aeronautical and space transportation fields, working to protect against adverse environmental conditions of flight, including pressure changes, reduced availability of oxygen, thermal stressors, accelerative forces, and psychosocial factors that might compromise performance.

History and Perspectives

People have sought to prevent illness throughout history, but the full concept of preventive medicine only developed with the emergence of modern medical science. The germ theory of disease and other breakthroughs led to radical changes in the understanding of disease and other aspects of health. Researchers increasingly recognized that prevention could be as or even more effective than treatment for many conditions, and new discoveries enabled innovative preventive methods.

One iconic example of preventive health in action was the pioneering observational epidemiology work of English physician John Snow in the mid-nineteenth century. During a cholera epidemic in London, Snow observed that the pattern of disease appeared to be dependent on the source of the water provided to each neighborhood. Recognizing that there was a high incidence of cholera in the Broad Street area, he was able to determine that most of the disease was associated with those families depending on the Broad Street pump for their drinking water. It has been said that he simply removed the handle on the pump and was able to control the epidemic in that area, illustrating the great potential of preventive measures to significantly impact public health.

Another famous historical example of the application of preventive medicine was the control of smallpox. In the late eighteenth century, physician and scientist Edward Jenner observed that the milkmaids in the English countryside were not scarred by the scourge of that highly infectious disease. On further examination, he determined that these young women had years earlier been infected with cowpox and thus had been spared the more serious smallpox infection. Jenner advocated intentional infection with cowpox to essentially vaccinate against smallpox, helping to inspire a wave of further research and development of vaccines. Years later, using this preventive medicine application, the World Health Organization (WHO) oversaw a successful push to eradicate smallpox worldwide. The world's last natural case of smallpox was reported in October 1977, marking the first time that a major human disease had been eradicated.

Neither the control of cholera in London by Snow nor the eradication of smallpox resulted from medical or surgical treatment of a disease. These results were obtained because of the application of the principles of preventive medicine and public health.

The power of preventive medicine is further reflected in a comparison of public health outcomes in the United States in 1900 with those in 2000. Over that period, the main causes of death underwent a major shift from infectious diseases to chronic diseases that often reflect individual lifestyles, such as cancer and heart disease. Public health experts noted that preventive medicine proved itself effective in altering both the causes of death and the age at which death occurs. In addition, there was a significant increase in the life expectancy of the population during the same century. Into the twenty-first century, preventive medicine increasingly expanded its focus to reducing morbidity and mortality from chronic diseases and accidents, particularly those in which an individual’s lifestyle increases the risk of illness and death.

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