Table 2.

Comparison between the 2 fundamental studies of the project

Lean Six Sigma Methodology to Reduce Healthcare Infections Project Federico II University Hospital in Naples
Comparison of the 2 fundamental Studies of the Project
	First Study	Second Study
Area of application	Surgery departments	Medicine areas
Number of analysed patients	20,000	28,000
Analysed period	January 2011 to December 2014	January 2011 to December 2016
Define phase	Statistical tools: project charter Gantt diagram SIPOC analysis critical‐to‐quality (CTQ) definitions	Statistical tools: project charter Gantt diagram CTQ definitions
Measure phase	Patient data are extracted from QUANI, a program developed by Bim Italia to record patients' hospital discharge data and flow data for the monitoring of sentinel bacteria. The used statistical tools are scatter box plot	Data for the study were extracted from the hospital database, which is able to record patients' hospital discharge data as well as flow data for the monitoring of sentinel bacteria. The used statistical tools are histograms, chi‐square tests, and Fisher tests.
Analyse phase	The used statistical tools are control chart histograms, chi‐square tests, and Fisher tests. Additionally, an Ishikawa fishbone diagram was developed to determine the root causes for the identified problem.	Analysis of the data collected during the measure phase. The used statistical tool is cause‐effect diagram and brainstorming sessions to deepen and validate the analysis of the root causes with the support of expert and healthcare staff.
Improve phase	Expert advice was obtained by administering a questionnaire to members of the Hospital Infection Committee that would allow them to indicate any necessary corrective measures to improve the process. A table summarizes all of the causes validated through the questionnaire and the corresponding corrective actions to be implemented in the process to optimize the process performance and reduce the risk of HAIs.	Expert advice was obtained by administering the same questionnaire. The previous phases and the questionnaire results allow for the identification of causes and the implementation of corrective actions to optimize the examined process.
Control phase	To control the course of the process, monitoring was performed by using process indicators.	To continuously improve the process and maintain a high standard of quality, a quality control plan was implemented.
Percentage of colonized patients	0.37%	0.36%
Implementing corrective actions	The application of corrective actions leads to a reduction in the percentage of colonized patients from 0.37% to 0.21%. Furthermore, the corrective actions significantly reduce the mean (SD) number of days of hospitalization from 45 (30.78) (with a data distribution approximately 2σ) to 36 (5.68) (with a data distribution approximately 3σ)	The percentage of colonized patients was reduced from 0.36% to 0.19% (only 25 patients of total patients analysed).