UNITED STATES PREVENTIVE SERVICES TASK FORCE (USPSTF)

The United States Preventive Services Task Force (USPSTF) is a group of nongovernmental experts convened by the U.S. Department of Health and Human Services to review published literature and develop recommendations for the use of clinical preventive services. The task force are experts chosen for their experience in the evaluation of clinical evidence and its application to the care of patients. The first task force patterned itself on a previous program in Canada. Its report, entitled Guide to Clinical Preventive Services, appeared in 1988. The second task force met between 1990 and 1995 and published a second edition of the guide in 1996. This second edition contained recommendations on 53 screening tests, 11 counseling interventions, 13 immunizations, and 6 medications to prevent illness. The third task force convened in 1998.

The concept of preventing disease probably began in the 1790s with Edward Jenner's cowpox vaccination against smallpox. The eradication of smallpox and the near-eradication of polio are among the triumphs of preventive medicine. "Disease prevention"—appropriate in the case of smallpox and polio—is a misnomer in most cases. "Risk reduction" is a more apt description of what preventive services actually do. Counseling about seat-belt use, immunization against influenza, and medications to prevent osteoporosis and fractures are examples of preventive services that reduce the risk of illness or injury. Other preventive services, exemplified by a screening test, detect disease before it can do harm. The goal of breast cancer screening is to detect cancer before it spreads beyond the breast. As with many diseases, especially cancers, early detection improves the chances for effective treatment.

A recommendation to provide a preventive service establishes a policy that will apply to everyone. Airbags are a good example. All cars have them, yet very few people will have an accident in which airbags will function to save their lives. This situation is typical of most preventive services: The target condition occurs infrequently in healthy people. Therefore, many people are exposed to the risks of airbags for each person who survives an accident because of airbags. This example shows that a recommendation for a preventive service should have solid evidence that its benefits exceed any harms. This fact is the principal justification for convening experts to evaluate and using a systematic approach to this task.

The current United States Preventive Services Task Force exemplifies a thorough approach to the evidence. Once the task force decides to make recommendations about a topic (e.g., screening for diabetes), a federally funded university-based group of scholars searches the published literature for evidence about the effect of the preventive service on health outcomes. The group evaluates the evidence, picks the best research, and summarizes it in tabular form and in an evidence report. The task force meets four times a year to decide on the quality of the evidence and to formulate a recommendation. These recommendations vary in their conviction depending on the strength of the evidence.

Before making a recommendation, the task force considers two features of the evidence. First, is the evidence valid? In other words, does the preventive service really do what the evidence seems to say? To form this judgment, the task force must be sure that the preventive service (e.g., lowering serum cholesterol) rather than other factors (such as a healthy lifestyle) is responsible for a reduction in the frequency of a disease such as coronary heart disease. Second, how large is the effect of the preventive service? If the evidence is strong and the preventive service has a large health effect, the task force will make a strongly favorable recommendation. Otherwise, the task force may recommend against doing the preventive service, or it may simply say that the evidence is too weak to make a recommendation for or against the preventive service.

The task force publishes supporting evidence to justify each of its recommendations. Each publication consists of a description of the burden of suffering from the target condition, the effect of the preventive service on the risk of the target condition, recommendations of other organizations, and a discussion of special aspects of the evidence. Each publication begins with a concise description of the recommendation and a summary rating of the strength of the evidence and ends with a description of the clinical intervention that physicians would provide.

Harold C. Sox

(see also: Clinical Preventive Services; Prevention; Prevention Research; Preventive Health Behavior; Preventive Medicine; Primary Prevention )

Bibliography

United States Preventive Services Task Force (1996). Guide to Clinical Preventive Services. Baltimore, MD: Williams and Wilkins. Also available at http://www.apchr.gov/clinic/cpsix.htm.

Woolf, S. H, and Sox, H. C. (1991). "The Expert Panel on Preventive Services: Continuing the Work of the U.S. Preventive Health Services Task Force." American Journal of Preventive Services 7:326–330.