Since the 1980s, the U.S. Preventive Services Task Force (USPSTF) has developed and used rigorous methods to make evidence-based recommendations about preventive services to promote health and well-being for all Americans. Recommendations are based on the evidence of magnitude of net benefit (benefits minus harms). Expert opinion is not substituted when evidence is lacking. Evidence gaps are common. Few preventive services are supported by high-quality studies that directly and comprehensively determine the overall magnitude of benefits and harms in the same study. When assessing the body of evidence, studies may not have been conducted in primary care settings, studies may not have sufficiently included populations of interest, and long-term outcomes may not have been directly assessed. When direct evidence is not available, the USPSTF uses the methodologies of applicability to determine whether evidence can be generalized to an asymptomatic primary care population; coherence to link bodies of evidence and create an indirect evidence pathway; extrapolation to make inferences across the indirect evidence pathway, extend evidence to populations not specifically studied, consider service delivery intervals, and infer long-term outcomes; and conceptual bounding to set theoretical lower or upper limits for plausible benefits or harms. The USPSTF extends the evidence only so far as to maintain at least moderate certainty that its findings are preserved. This manuscript details with examples of how the USPSTF uses these methods to make recommendations that truly reflect the evidence.

The U.S. Preventive Services Task Force (USPSTF) summarizes the principles and considerations that guide development of its recommendations for diverse U.S. populations. It uses these principles through each step in the evidence-based guideline process: developing the research plan, conducting the evidence review, developing the recommendation, and communicating to guideline users. Three recent recommendations provide examples of how the USPSTF has used these principles: the 2015 recommendation on screening for abnormal blood glucose and type 2 diabetes; the 2016 recommendation on screening for breast cancer; and the recommendation on screening for prostate cancer, which is currently in progress. A more comprehensive list of recommendations that includes considerations for specific populations is also provided.