Background: Popular quality improvement tools such as Six Sigma and Lean Systems (SS/L) claim to provide health care managers the opportunity to improve health care quality on the basis of sound methodology and data. However, it is unclear whether these 2 quality improvement tools actually improve health care quality.
Methods: The authors conducted a comprehensive literature review to assess the empirical evidence relating SS/L to improved clinical outcomes, processes of care, and financial performance of health care organizations.
Results: The authors identified 177 articles on SS/L published in the last 10 years. However, only 34 of them reported any outcomes of the SS/L projects studied, and less than one-third of these articles included statistical analyses to test for significant changes in outcomes.
Conclusions: This review demonstrates that there are significant gaps in the SS/L health care quality improvement literature and very weak evidence that SS/L improve health care quality.