Background: Health technology assessment (HTA) involves systematic synthesis of evidence using rigorous scientific methodology. A key goal is reducing bias that may occur in clinical studies and in the evidence assessment process. However, evidence gaps are common. Moreover, many medical decisions involve close calls in risk to benefit analysis and in quality of life trade-offs. The values and beliefs of key stakeholders that determine what to do when faced with medical uncertainty vary among key stakeholders and are not a matter of science, but a matter of policy. A central issue is how to incorporate researcher and health care user values into the development and communication of guidelines recommendations.

Methods: We analyze the US Preventive Services Task Force (USPSTF) experience with developing and communicating breast cancer screening recommendations for healthy women in their 40s as a recent example of the type of highly charged controversy that may arise when HTAs fail to adequately incorporate and communicate patient and consumer values and consider funding implications.

Results: Although this HTA process was driven by the highest scientific ideals, ethical and political issues that arose in the wake of the controversy forced the US government to aggressively intervene by de-emphasizing the role of the expert panels as policy makers; adopting legislation providing no-cost mammograms; and pressuring the task force to revise its recommendations to emphasize that the final decision belonged to the individual.

Conclusions: Participation by informed consumer representatives in the process may have helped bridge the gap between scientific and patient values and avoided this controversy by ensuring that the language of the recommendation properly identified important patient values and preserved individualized decision making within an evidence-based structure. The perceived legitimacy of an HTA process depends upon adequately resolving conflicting values in their political and societal context.