What Is Lean Management in Health Care? Development of an Operational Definition for a Cochrane Systematic Review

Importance of an Operational Definition

Without an agreed upon a definition or inclusion criteria, especially in health care, studies investigating Lean implementation often lack relevant information (Mazzocato et al., 2012) and vaguely refer to Lean management, Lean principles, or Lean thinking (Atkinson & Mukaetova-Ladinska, 2012; G. Smith, Poteat-Godwin, Harrison, & Randolph, 2012; Van Vliet et al., 2011; Vegting et al., 2012).

This article describes the process and outcomes related to creating an evidence-informed operational definition of Lean health-care management. An iterative process of testing, updating, and retesting the criteria was used to identify relevant characteristics; this approach has been suggested by Kinsman, Rotter, James, Snow, and Willis (2010) and Wieland, Manheimer, and Berman (2011).

It is important to note that this process was used to develop an operational, rather than a theoretical, definition. A theoretical definition characterizes the fundamental nature of a construct. In contrast, an operational definition provides a concrete test to determine whether or not a specific example falls within that construct (Wieland, Manheimer, & Berman, 2011). This difference is illustrated by Wieland et al. (2011) who provide the example of a randomized control trial for depression medication. In such a trial, the theoretical construct of the disease being treated is “depression,” but the operational definition may be a score of 20 or more on the Beck Depression Inventory or answering “yes” to the question “Are you depressed?” As such, the operational definition brings practical use to a theoretical construct. The need for an operational definition of Lean is supported in a review by Bhamu and Sangwan (2014), which identified 33 definitions of Lean used in OM. Since all of the definitions were theoretical, rather than operational, they could not be applied as content inclusion criteria.

Literature Search

We developed a search strategy (Online Supplemental Content File 1) for OVID MEDLINE and searched from database inception on 1946 to December 2013. The strategy was comprised of key word phrases since there were no Medical Subject Headings to describe Lean management in health care. The search phrases included the word “Lean” in proximity to a group of synonyms aimed at identifying management processes (e.g., organization, management, process, and technique). This search was the first stage in the iterative process of developing a search strategy for our systematic review. At this point, the search strategy was not intended to identify all applications of Lean management.

Screening Methods

Primary studies were initially included or excluded using the definition and inclusion criteria published in the systematic review protocol (Lawal et al., 2014). The population, intervention, comparison, and outcomes used as inclusion/exclusion criteria in the protocol are presented in Online Supplemental Content File 2.

Titles and abstracts of search results were screened for inclusion independently by two authors. Disagreements were resolved by discussion or by a third author. After title and abstract screening was completed, the full text of the remaining primary articles was retrieved and assessed.

Data Extraction

Two authors independently extracted the descriptions of Lean interventions used in each of the 33 primary articles. Results of this process showed that 27 articles mentioned some aspect of Lean thinking, Lean philosophy, or Lean-based continuous improvement throughout the organization or a subunit of the organization; 26 studies described the use of value-stream mapping (VSM); 15 studies illustrated the use of a Rapid Process Improvement Workshop (RPIW); 7 studies utilized sort, sweep, simplify, standardize, and sustain/self-discipline (5S) methodologies; 6 studies reported the use of Gemba walks; 4 depicted standard work; 3 studies reported A3 problem-solving; 3 studies utilized leveled production; 3 studies illustrated the use of daily visual management (DVM); and 2 studies applied stop the line techniques. Details regarding the methods and Lean activities used in each study can be found in Table 2.

Data Synthesis

Based on the extracted information, we summarized key characteristics into two themes that encompass the defining elements of Lean management in health care: Lean philosophy (characterized by Lean principles and continuous improvement) and Lean activities (characterized by assessment and improvement activities). These themes underpin the definition developed and are operationalized in the following list:

• Lean philosophy is a set of ideas at the center of Lean. Lean philosophy is made up of Lean principles and continuous improvement:

  • Lean principles refer to an overarching set of principles aimed at transforming workplace culture (Kruskal, Reedy, Pascal, Rosen, & Boiselle, 2012). These include a focus on eliminating waste (DelliFraine, Langabeer, & Nembhard, 2010; Mazzocato, Savage, Brommels, Aronsson, & Thor, 2010; Poksinska, 2010); improving the flow of patients, providers, and supplies (Black & Miller, 2008; Holden, 2011; Poksinska, 2010); and ensuring all processes add value to customers (Kim, Spahlinger, Kin, & Billi, 2006). Further, Lean principles suggest that problems are identified and addressed by frontline staff members as it is believed that the people doing the work are best suited to create solutions (Casey, Brinton, & Gonzalez, 2009; Holden, 2011; Kruskal et al., 2012).
  • Continuous improvement refers to the acknowledgment that Lean does not occur as a single intervention but instead requires ongoing efforts and interventions aimed at improving the workplace (DelliFraine et al., 2010; Holden, 2011; Mazzocato et al., 2010).
• Lean activities are a set of management practices, tools, or techniques that can be directly observed and are prescribed to improve the workplace. There are two types of Lean activities: assessment activities and improvement activities.

  • Lean assessment activities work as analytic tools to identify waste and areas of possible improvement. These activities allow team members to see problems and identify opportunities to reduce waste and make improvements but do not prescribe specific solutions. Lean assessment activities include VSM, spaghetti diagrams, RPIWs, Gemba walks, and root cause analysis.
  • Lean improvement activities suggest specific ways to reduce waste, improve the workplace, and set up new working practices. These include actions and concepts such as 5S events, leveled production, DVM (including Kanban supply management), standard work, and stop the line techniques.

Operational Definition

Based on the themes identified, we created an operational definition of Lean management in health care that will act as an objective screening criterion for our systematic review. The resulting operational definition requires that included studies describe an organization or subunit of an organization (e.g., department or ward) which

1. integrated Lean philosophy into the organization’s mandate, guidelines, or policies and demonstrated by (1a) evidence of Lean principles and (1b) evidence of continuous improvement; and
2. utilized at least one Lean activity and demonstrated by (2a) evidence of a Lean assessment activity or (2b) evidence of a Lean improvement activity.

Evidence of (1a) Lean principles was considered sufficient where there was an explicit statement that the organization had adopted Lean management or an in-house system based on Lean (e.g., the Virginia Mason production system) or a management system which explicitly incorporates the following three components: reducing waste, improving flow, and utilizing an employee-driven approach to improvement. Evidence of (1b) continuous improvement was considered sufficient when there was a statement asserting that the organization had created a dedicated quality improvement team/unit or that the organization conducted at least two distinct quality improvement projects including any projects described in the article.

Evidence of Lean activities was considered sufficient when the study described the use of (2a) a Lean assessment activity (e.g., VSM, spaghetti diagrams, RPIWs, Gemba walks, or root cause analysis) or (2b) a Lean improvement activity (e.g., 5S events, leveled production, DVM, standard work, or stop the line techniques) or both. A screening form demonstrating how the operational definition will be used can be found in Table 3.

Testing of Operational Definition

In order to test the coherence between the 33 primary studies and the operational definition, the definition was applied to each of the studies identified. Results indicated that 27 of the 33 studies fit well with the criteria and were included based on this definition. The remaining six studies were excluded due to their failure to demonstrate integration of Lean philosophy. Information regarding changes in inclusion status can be found in Online Supplemental Content File 3. Additional information regarding excluded studies is available in Online Supplemental Content File 6. Of the 27 included studies, 15 reported only a Lean assessment activity, 11 reported both assessment and improvement activities, and 1 study reported using only a Lean improvement activity. As noted, details on activities used are presented in Table 2.

Study Selection After Applying Operational Definition (Rescreening)

All 511 search results were rescreened based on the operational definition presented above. During the title and abstract rescreening phase, 367 records not meeting the inclusion criteria were excluded. Full-text assessment of the remaining 136 records resulted in selecting 43 studies. This process excluded six previously included studies and included 16 previously excluded studies. Details on newly included and excluded studies can be found in Online Supplemental Content File 3. The flowchart for this process can be found in Online Supplemental Content File 7, and decisions for each article can be found in Online Supplemental Content File 8.

Interrater Reliability

Screening results for full-text articles led to a consensus to include 43 studies and exclude 77 studies with disagreement on 16 studies prior to discussion. These results suggest approximately 88% agreement. Statistical testing suggested excellent agreement between judgments, K = 0.753, p < .001. Following discussion, agreement was reached for all 136 studies.

Coherence With the Literature

The definition developed fits well with the current literature, operationalizing many of the characteristics identified in previous reviews. The Lean activities identified are similar to those reported in the work by Radnor, Holweg, and Waring (2012), which identifies “assessment activities,” “improvement activities,” and “performance monitoring activities.” However, we did not identify the “performance monitoring activities” described by Radnor et al. This may have resulted from the fact that only four studies from the original screening phase and five studies from the rescreening phase provided follow-up data for more than 24 months.

Further, the Lean characteristics identified in this article align well with the work of Poksinska (2010), which describes the steps of Lean implementation as “focusing on the patient as the primary customer” (“patient orientation”), “learning to see process shortcomings,” and “specifying how work should be done.” In this case, “patient orientation” is comparable with the integration of “Lean principles,” while “learning to see process shortcomings” and “specifying how work should be done” are analogous to “assessment activities” and “improvement activities,” respectively. Finally, parallels can be seen between “Lean philosophy” and “Lean activities” and the work of Hines, Holweg, and Rich (2004), which notes that Lean exists at both the “strategic” and “operational” levels.

It is also interesting to note that the priorities identified in the operational definition only partially overlap with those presented in much of the OM literature. For example, the focus on including frontline staff, committing to continuous improvement, and utilizing standard work mesh well with the concepts of total quality management and human resource management outlined by Shah and Ward (2003); however, we found little emphasis on just-in-time systems and total productive maintenance.

Similarly, the integration of “continuous improvement” and “Lean principles” is in line with the areas of “Lean implementation” and “workforce management” identified by Papadopoulou and Ozbayrak (2005). Further, the “Lean activities” we identified seem to focus on the “product/process-oriented” and “production, planning, scheduling, and control” areas described by Papadopoulou and Ozbayrak. In contrast, “production floor management” and “supply chain management” appear deemphasized. Exploration of the reasons for these differences is outside the scope of this article, but we hope to focus on this area in subsequent publications.

Sustainability and Study Type

Among all the studies utilized in the development of the operational definition, only four had follow-up periods greater than 24 months. Furthermore, all studies identified were empirical studies rather than theoretical or conceptual articles. As a result, the studies captured are likely to be focused on the process of implementing Lean interventions rather than providing a conceptual framework for Lean. Taken together, these points suggest that the operational definition developed best describes organizations in the early stages of Lean implementation. As such, future research will be needed to determine whether the definition is applicable to organizations which have been utilizing Lean for an extended period of time.

Lean Assessment and Improvement Activities

The issue of an imperfect distinction between assessment and improvement activities results from the fact that characterizations were made based on the primary nature of each activity. However, many Lean activities include both assessment and improvement components. This can be seen in 5S events, where the “sort” component requires team members to identify and eliminate unneeded tools, parts, or supplies, thereby acting as an assessment activity. In contrast, the “set in order” and “standardize” components dictate that items should have a standardized location and that these locations should be visually represented; therefore, these components act as a Lean improvement activity.

Importance of an Operational Definition

The application of the operational definition to the 511 search hits unambiguously illustrates the importance of having a clear operational definition for systematic reviews. Without using the operational definition, 16 relevant studies would have been missed and 6 irrelevant studies would have been included. This resulted in a net increase of 10 studies (23% of included studies). It is noteworthy that applying the operational definition resulted in a substantially higher number of studies included (43 studies) as compared to 33 studies included using the definition and inclusion criteria published in the systematic review protocol (Lawal et al., 2014). It is also important to note that the operational definition developed showed an excellent level of agreement, demonstrating consistent application.

The relatively weak definitions relating to Lean were also obvious in the way Lean methods were reported in the literature. One major shortcoming identified was that many authors did not have a standard template outlining which components of an organization’s use of Lean should be described. This was most obvious in reporting of Lean philosophy as it was unclear whether some organizations had integrated Lean philosophy or whether the intervention was a single “Lean-inspired experiment.” For this reason, six of the originally included studies were excluded. This is a necessary distinction as Lean is an overall management system rather than a set of tools (Bhasin & Burcher, 2006). Many tools such as VSM, spaghetti diagrams, and root cause analysis are not unique to Lean and are used in other continuous quality improvement approaches. As such, it is hoped that this operational definition will help improve reporting of Lean interventions used in health care.

We acknowledge the financial support provided for this project and the critical appraisal and help provided by Dr. Gary Teare, CEO of Saskatchewan Health Quality Council.