Changing the skill-mix of the health care workforce. 
Changing workforce skill-mix is one strategy for improving the effectiveness and efficiency of health care.  Our aim was to summarise available research into the success or failure of skill-mix change in achieving planned outcomes.  A systematic search for existing reviews of research into skill-mix was conducted.  Databases searched included: MEDLINE, CINAHL, PsychINFO, Cochrane Library, HMIC, Centre for Reviews and Dissemination, and Department of Health Research Findings Register.  Search terms included keywords defining the type of publication, clinical area, type of health personnel and the focus of the article (role change, skill-mix, etc.).  English language publications from 1990 onwards were included.  Two reviewers independently identified relevant publications, graded the quality of reviews and extracted findings.  In addition, the wider literature was scanned to identify which factors were associated with the success or failure of skill-mix change.  A total of 9064 publications were identified, of which 24 met our inclusion criteria.  There was a dearth of research, particularly for role changes involving workers other than doctors or nurses.  Cost-effectiveness was generally not evaluated, nor was the wider impact of change on health care systems.  The wider literature suggested that factors promoting success include: introducing 'treatments' of proven efficacy; appropriate staff education and training; removal of unhelpful boundary demarcations between staff or service sectors; appropriate pay and reward systems; and good strategic planning and human resource management.  Unintended consequences sometimes occurred in respect of: staff morale and workload; coordination of care; continuity of care; and cost.  In order to make informed choices, health care planners need good research evidence about the likely consequences of skill-mix change.  The findings from existing research need to be made more accessible while the dearth of evidence makes new research necessary.