Evidence and quality, practicalities and judgments: some experience from NICE.

The National Institute for Health and Clinical Excellence (NICE) is the principal provider of information about the evidence relating to effectiveness and cost-effectiveness in healthcare in the National Health Service of England and Wales. NICE regards quality as primarily to do with effectiveness, safety and the patient experience. In this paper we comment on the quality of evidence regarding these three and speculate about the consequences of widening the range of interventions for appraisal and taking more complete account of upstream determinants of health. We also comment on the type and quality of the evidence, as well as the way in which it is used, and the values--too often hidden--that permeate both the evidence and the way in which it is used.