Clinical effectiveness is the degree to which the organisation is ensuring that 'best practice', based on evidence of effectiveness where such evidence exists, is used. The Department of Health defined clinical effectiveness as 'the extent to which specific interventions, when deployed in the field for a particular patient or population, do what they are intended to do, for example, maintain and improve health and secure the greatest possible health gain from available sources'. 

Clinical effectiveness has been described by Professor Alison Kitson at a conference in London in 1995 as 'doing the right thing' and 'doing the thing right', with the former requirement relating to the effective utilisation of research through mechanisms such as clinical guidelines, which are rigorously developed. The latter requirement relates to how such information is implemented.'

The concept of clinical effectiveness is that healthcare treatments should be clinically effective and cost-effective, supported by a well-researched evidence base. The Royal College of Nursing outlined the main elements of clinical effectiveness as the:

• production of evidence through research and scientific review
• production and dissemination of evidence-based clinical guidelines
• implementation of evidence-based, cost-effective practice through education and change management
• evaluation of compliance to agreed practice guidance and evaluation of patient outcomes, including clinical audit