Our Nation's health service delivery systems face growing challenges to enhance quality while reducing costs. Lean/Toyota Production Systems (TPS) is a process redesign strategy developed in manufacturing that promises to help health care delivery systems meet these twin challenges. Lean/TPS is a method for eliminating "waste"—defined as any activity that consumes resources without enhancing value to those being served by the process. This literature review explores possible adaptation of Lean/TPS to health care settings.
Our Nation's health service delivery systems face growing challenges to enhance quality while reducing costs. Lean/Toyota Production Systems (TPS) is a process redesign strategy developed in manufacturing that promises to help health care delivery systems meet these twin challenges. Lean/TPS is a method for eliminating "waste"—defined as any activity that consumes resources without enhancing value to those being served by the process.
In response to growing interest in Lean/TPS, the Agency for Healthcare Research and Quality (AHRQ) seeks to understand whether this innovative approach to quality improvement works in health care. If so, the goal is to identify the organizational and contextual factors that may systematically contribute to successful adoption of Lean/TPS. This literature review was designed to begin to answer these questions.
We searched peer-reviewed literature using academic databases, conducted an Internet search of gray literature, and reviewed documents provided by our project team and Lean/TPS experts. We also briefly reviewed literature about quality improvement and organizational learning, innovation, and change. To guide our efforts, we first developed a framework of the factors likely to affect Lean implementation across a variety of health care settings. These factors include contextual (organizational and environmental) variables, as well as variables associated with different change methodologies, project goals, and outcomes.
State of the Literature
The published and Internet literature does not consistently report important information about key dimensions and elements that we identified as potentially important for understanding Lean/TPS implementation. For example, there was little rigorous reporting about external impetus for Lean/TPS (e.g., market factors), organizational factors (e.g., how culture affects who implements Lean/TPS), outcomes (e.g., financial, quality), and sustainability. In addition, although there was a large volume of gray literature, we found only 31 relevant peer-reviewed articles. Many publications and reports are anecdotal and insufficiently documented.
More specifically, the literature (peer-reviewed and gray literature) displayed the following methodological limitations:
- Although many studies reported tangible results, few explained the methods by which the results were obtained.
- Nearly all the documents focused on a single organization, department, and project. It was very difficult to determine which features of organizations-and the external environments in which they operate-are important for successful implementation and maintenance of Lean/TPS.
- Studies generally failed to use rigorous quasi-experimental designs or comparative and longitudinal case study designs. Instead, most studies reported on case studies without documenting the use of rigorous case study methodologies.
- The Lean/TPS literature appears to have a positive publication bias. All but three documents reported positive outcomes from implementing Lean/TPS. This finding may have been related to the fact that most of the documents were authored by individuals who implemented the projects, rather than by independent investigators.
Preliminary Findings from the Literature
As a result of these limitations, the scan did not provide a solid evidence base about the effects of Lean/TPS applications in health care or about implementation practices and contexts that may shape its use or outcomes. The literature did, however, reveal the following trends that merit further investigation*:
- Implementation of Lean was reported in more than 50 locations across every geographic region in the United States and three foreign countries.*
- Internal impetus for adopting Lean/TPS was described more frequently than external impetus. Internal pressures included the need or desire to improve a given error rate, untenable organizational circumstances leading to clinician and staff frustration, or an internal "crisis" (e.g., a medical error resulting in patient harm).
- Most projects aimed at improving efficiency and quality at the departmental level, but a few organizations sought to use Lean to drive systemwide change.
- Lean projects were implemented in both clinical areas (e.g., laboratories, surgical units, emergency departments, endoscopy, gynecology, and intensive care) and administrative areas (billing, central scheduling, and medical records). Processes with linear workflows were targeted more frequently than nonlinear processes.*
- The most commonly cited activities were value stream (i.e., process) mapping and 5S (an organizing tool); Kaizen events (weeklong events to manage a specific process) were frequently cited as well.*
- Implementation teams ranged in size from one individual up to 17 and varied in composition, often including senior, mid-level, and frontline staff. Specific staff included physicians, nurses, technicians, quality improvement and redesign professionals, unit directors, department chairpersons, and Lean/TPS specialists.
- Champion/opinion leaders tended to occupy high-level administrative positions (e.g., chief executive officers, vice presidents, or department directors), although several identified champions were departmental level management staff.
- Change agents were typically outside experts with experience in Lean/TPS, often described as "facilitators," "trainers," "consultants," and "specialists."
- Impact was assessed using efficiency measures (cycle or turnover time, specimens per hour, cases per day/week, reductions in practitioners' walking distances, cost savings); measures of quality and safety (number of adverse events, bloodstream infections, overall rates of infection, medication errors); and measures of patient satisfaction.*
Further AHRQ research in the application of Lean/TPS across diverse health care delivery settings is currently underway. The full literature review, which was conducted for AHRQ by the American Institutes of Research, will soon be available. In the interim, please do not cite or quote this draft summary. For more information on AHRQ work on process redesign, please visit System Design: AHRQ Resources.
* Findings denoted with asterisks were observed in 75 percent or more of the studies (including both peer-reviewed articles and gray literature); those without asterisks were observed in at least 25 percent, but fewer than 75 percent, of the studies.