Clinical audit is a process that has been defined as "a quality improvement process that seeks to improve patient care and outcomes through systematic review of care against explicit criteria and the implementation of change".

may be this guide help you: http://www.rcseng.ac.uk/healthcare-bodies/docs/guide-to-quality-improvement-methods

Thanks for your comment.

Yes i agree that the QI as a concept in health care is not producing the expected results when compared to other areas such as industrial QI. 

Is there a measure to identify the efficacy of the Clinical Audit as QI?

There are many descriptive analysis and proposal that Clinical Audit can be QI, however, only dearth evidence is available to assure the use as QI