Dealing with uncertainty: will science solve the problems of resource allocation in the U.K. NHS?

In spite of the huge efforts which internationally address the development and assessment of health technologies, the majority of health care interventions have not been formally evaluated for their effectiveness and their likely impact upon health status is largely unknown. This has led to a situation where it is unclear on what basis a health care system might be judged, or for that matter on what basis decisions on the specification of individual services might be made. It has frequently been argued that the only way to build an adequate understanding of the effectiveness of different interventions is through systematically locating and synthesising the available evidence from research, and such systematic overviews are increasingly available in many areas. However, such overviews produce few clear conclusions, and even when the results of systematic overviews show unequivocal benefits for patients, implementing the findings of such reviews remains problematic. Research evidence provides useful information on marginal benefits for patients, though areas where the absolute benefit is high appear to be very rare. The most common finding appears to be uncertainty. Interpreting research evidence is complex, and even very clear findings may prove hard to operationalise. Good quality research will help, but will not solve, the problems of resource allocation in the NHS or in other health systems.