Background: The evidence supporting the use of new, or established, interventions may be derived from either (or both) experimental or observational study designs. Although a rigorous examination of the evidence base for clinical and cost-effectiveness is essential, it is never sufficient, and those undertaking a health technology assessment (HTA) also have to exercise judgments.
Methods: The basis for this discussion is largely from the author's experience as chairman of the national Institute for Health and Clinical Excellence (NICE).
Results: The judgments necessary for HTA to make are twofold. Scientific judgments relate to the interpretation of the science. Social value judgments are concerned with the ethical principles, preferences, culture, and aspirations of society.
Conclusions: How scientific and social value judgments might be most appropriately captured is a challenge for all HTA agencies. Although competent HTA bodies should be able to exercise scientific judgments they have no legitimacy to impose their own social values. These must ultimately be informed by the general public.
