title: The use of Lean and Six Sigma methodologies in surgery: a systematic review.
abstract: BACKGROUND
  Lean and Six Sigma are improvement methodologies developed in the manufacturing industry and have been applied to healthcare settings since the 1990 s. They use a systematic and reproducible approach to provide Quality Improvement (QI), with a flexible process that can be applied to a range of outcomes across different patient groups. This review assesses the literature with regard to the use and utility of Lean and Six Sigma methodologies in surgery.
  
  
  METHODS
  MEDLINE, Embase, PsycINFO, Allied and Complementary Medicine Database, British Nursing Index, Cumulative Index to Nursing and Allied Health Literature, Health Business Elite and the Health Management Information Consortium were searched in January 2014. Experimental studies were included if they assessed the use of Lean or Six Sigma on the ability to improve specified outcomes in surgical patients.
  
  
  RESULTS
  Of the 124 studies returned, 23 were suitable for inclusion with 11 assessing Lean, 6 Six Sigma and 6 Lean Six Sigma. The broad range of outcomes can be collated into six common aims: to optimise outpatient efficiency, to improve operating theatre efficiency, to decrease operative complications, to reduce ward-based harms, to reduce mortality and to limit unnecessary cost and length of stay. The majority of studies (88%) demonstrate improvement; however high levels of systematic bias and imprecision were evident.
  
  
  CONCLUSIONS
  Lean and Six Sigma QI methodologies have the potential to produce clinically significant improvement for surgical patients. However there is a need to conduct high-quality studies with low risk of systematic bias in order to further understand their role.
authors.affiliation: Division of Surgery, Imperial College London, St Mary's Campus, London W2 1NY, UK.
authors.forename: S E
authors.initials: SE
authors.lastname: Mason
authors.affiliation: Division of Surgery, Imperial College London, St Mary's Campus, London W2 1NY, UK. Electronic address: c.nicolay@imperial.ac.uk.
authors.forename: C R
authors.initials: CR
authors.lastname: Nicolay
authors.affiliation: Division of Surgery, Imperial College London, St Mary's Campus, London W2 1NY, UK.
authors.forename: A
authors.initials: A
authors.lastname: Darzi
mesh_terms: D017598:Efficiency, Organizational; D006801:Humans; D007902:Length of Stay; D009873:Operating Rooms / Q000458:organization & administration*; D061214:Patient Safety / Q000592:standards*; D011183:Postoperative Complications / Q000517:prevention & control*; D058996:Quality Improvement / Q000458:organization & administration*; D013514:Surgical Procedures, Operative / Q000401:mortality* / Q000592:standards; D017749:Total Quality Management / Q000592:standards
keywords: Lean; Lean six sigma; Quality improvement; Six sigma; Surgery; Total quality management