Levels of Prevention

Levels of Prevention

     The definition of epidemiology encompasses preventing and controlling diseases in human populations. This is usually accomplished using three levels of prevention. Primary prevention seeks to reduce the frequency of new cases of disease occurring in a population and, thus is most applicable to persons who are in the stage of susceptibility. Secondary prevention attempts to reduce the number of existing cases in a population and, therefore, is most appropriately aimed those in the stage of presymptomatec disease or the early stage of clinical disease. Tertiary prevention tries to limit disability and improve functioning following disease or its complications, often through rehabilitation. Therefore, it is most applicable during the late clinical stage or the stage of diminished capacity. The natural history of disease and the levels of prevention are closely linked. As illustrated in figure 3-4, appropriate levels of prevention may be applied at each stage of the natural history of disease.

Primary Prevention

     Primary prevention strategies emphasize general health promotion, risk factor reduction, and other health protective measures. These strategies include health education and health promotion programs designed to foster healthier lifestyles and environmental health programs designed to improve environmental quality. Specific examples of primary prevention measures include immunization against communicable diseases; public health education about good nutrition, exercise, stress management, and individual responsibility for health; chlorination and filtration of public water supplies; and legislation requiring child restraints in motor vehicles.

Secondary Prevention

     Secondary prevention focuses on early detection and swift treatment of disease. Its purpose is to cure disease, slow its progression, or reduce its impact on individuals or communities. A common approach to secondary prevention is screening for disease, such as the noninvasive computerized test for the early detection of heart disease. This test uses computerized tomography scans to look for calcium deposition in the arteries, which can signal previously undetected heart disease. Other examples of screening include mammography for breast cancer detection; eye tests for glaucoma; blood tests for lead exposure; occult blood tests for colorectal cancer; the Pap test for cervical concrete breath test for Helicobacter pylori, the bacterium implicated in duodenal and gastric ulcers; and the Prostate-Specific Antigen(PSA) test for prostate cancer. In each case, screening is performed to detect disease early so prompt treatment can be initiated. Examples of other secondary prevention methods include treatment of hypertension to prevent complications and removal of skin cancer lesions as they occur.

Tertiary Prevention

     Tertiary Prevention strategies involve both therapeutic and rehabilitative measures once disease is firmly established. Examples include treatment of diabetics to prevent complication of the disease and the ongoing management of chronic heart disease patients with medication, diet, exercise, and periodic examination. Other examples include improving functioning of stroke patients through rehabilitation by occupational and physical therapy, nursing care, speech therapy, counseling, and so forth, and treating those suffering from complications of diseases such as meningitis, multiple sclerosis, or Parkinson’s disease.