Defining the nursing contribution to patient outcome: lessons from a review of the literature examining nursing outcomes, skill mix and changing roles.

A review of the evidence to define the nursing contribution to patient outcome is presented. The review relies on work related to nursing sensitive outcomes, skill mix and changing roles. Methodological difficulties associated with these studies are highlighted. Areas requiring further research are discussed. It is suggested that experimental evidence is not always appropriate, when attempting to describe nursing activity. The authors advocate that new methodologies, in particular practitioner-centred research, are needed to unpack the nature of nursing.