Evaluating change in health care practice: lessons from three studies.

Implementation and evaluation of evidence-based practice are high on the policy agenda in the UK National Health Service. Over the last 30 years evaluation of practice in the health services has moved from a (medical) profession-led mode to a politically and managerially led mode in which objectives are pre-set by those who legitimate and fund the services. Against this background we describe three recent evaluations of nursing practice as examples to illustrate challenges encountered when evaluating changes in practice developments in health care. If evaluations are to contribute to improvements in practice, a shift is needed from an over-reliance on one-off outcome evaluations to those that have a cumulative component and take account of context and process as well as outcome. The merits of realistic evaluation are suggested as a solution to the methodological limitations of traditional approaches and to developing generalizable theory.