Small Tests Over Big Rollouts: Why the Model for Improvement Beat Lean and Six Sigma as the Frame for a Blood Culture Collection Bundle
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Doctor of Nursing Practice Program, Aspen University
DNP860: Evidence-Based Practice for Quality Improvement
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Month Day, Year
Small Tests Over Big Rollouts: Why the Model for Improvement Beat Lean and Six Sigma as the Frame for a Blood Culture Collection Bundle
An improvement model gives a project its structure: how problems are defined, how changes are designed and tested, and how success is judged. Choosing one deliberately matters, because models differ in what they emphasize and what they demand of a team. This paper states criteria for selecting a model for the emergency department blood culture contamination project, compares three widely used approaches, the Model for Improvement, Lean, and Six Sigma, and justifies the choice of the Model for Improvement.
Selection Criteria
Five criteria guided the choice. First, fit with the evidence: the appraisal found good evidence for each bundle component individually but none for the three together, so the model must allow components to be introduced and evaluated in sequence. Second, fit with the setting: a community emergency department with high turnover and no dedicated improvement staff. Third, speed of learning: the team wants early signals rather than waiting months for a full analysis. Fourth, data demands: the model must work with monthly contamination data from the laboratory. Fifth, evidence of effectiveness for the model itself in health care.
The Model for Improvement
The Model for Improvement opens with three questions that fix the aim, the measures that will show progress, and the ideas worth testing. It then tests changes through plan-do-study-act cycles, each of which states in advance what the team expects, tries the change on a small scale, compares what happened with what was expected, and decides what to do next (Langley et al., 2009). Tests begin small, such as one nurse on one shift, and grow as confidence increases.
The model fits the criteria well. It allows each bundle component to be tested separately and in sequence. It requires no specialized statistical training, which suits a team without improvement staff. Small cycles produce early learning. It works with run charts of monthly or weekly data. Its main weakness lies in how it is often applied rather than in the model itself. A systematic review of 73 articles reporting the use of plan-do-study-act cycles found that fewer than 20 percent fully documented a sequence of iterative cycles and only 15 percent of those analyzed let data gathered at least once a month steer them from one cycle to the next (Taylor et al., 2014). The model works when its discipline is kept; the risk is calling a single rollout a cycle.
Lean
Lean focuses on eliminating waste and improving flow by mapping the value stream, identifying steps that do not add value for the patient, and redesigning processes around the work. It would be useful for mapping how blood culture collection fits into the emergency department's flow, for example to reduce the time nurses spend gathering supplies for sterile collection. But its emphasis is on efficiency and flow rather than on reducing a specific defect, and a full value stream analysis would require facilitation expertise the department lacks. Lean tools, such as standardized work and supply kits at the point of care, can be borrowed within the Model for Improvement.
Six Sigma
Six Sigma aims to reduce variation and defects through the DMAIC cycle, define, measure, analyze, improve, and control, using statistical tools to identify root causes. Blood culture contamination is a defect with a clear rate, which makes Six Sigma attractive in principle. However, it typically requires trained belts, extensive baseline measurement, and statistical analysis before changes are made, which would slow the project and exceed the team's resources. Its evidence base in health care is also limited: a review of 177 articles on Six Sigma and Lean in health care found that only 34 reported any outcomes and fewer than a third of those included statistical tests of change, concluding that evidence that these approaches improve quality was very weak (DelliFraine et al., 2010).
The Decision
The Model for Improvement best meets the criteria. It supports sequential testing of the bundle's components, suits a team without specialized training, produces early learning, works with available data, and, although evidence about improvement models in general is limited, it is the most widely used and documented approach in health care. Lean tools will be borrowed for standardizing supplies, and the Six Sigma emphasis on defining the defect precisely has already shaped the definition of contamination used in the project.
What the Choice Commits the Project To
Choosing the Model for Improvement commits the team to its discipline. The aim will be stated with a number and a date: reduce contamination from 4.1 percent to below 2 percent within nine months. Each cycle will start with a written prediction and end with a documented decision to adopt, adapt, or abandon the change. The first cycle will test separate venipuncture with one nurse on day shift for one week; later cycles will add sterile technique and then diversion, expanding by shift and pod. Data will be plotted on run charts weekly. These commitments address the weaknesses the review of plan-do-study-act use identified.
Team Roles Within the Model
The model also shapes who does what. The DNP student will serve as improvement lead, responsible for keeping the cycle log, the run charts, and the discipline of predictions. Two emergency nurses, a day-shift and a night-shift colleague, will design and run each test on their shifts, because a change designed by the nurses who will carry it out tends to fit the realities of a busy shift. The microbiology supervisor will provide weekly contamination data by collector and method, and the infection preventionist will review each cycle's results with the team. The emergency department nurse manager will sponsor the project, protect time for the team's 30-minute weekly meeting, and remove barriers such as supply shortages. Writing these roles down at the start prevents the common pattern in which the improvement lead ends up running every test alone.
Conclusion
The Model for Improvement was selected over Lean and Six Sigma because it allows the bundle's components to be tested in sequence, suits a team without specialized training, and produces early learning from available data. Its known weakness, loose application, will be managed by committing to documented predictions, iterative cycles, and frequent data. Tools from the other approaches will be used where they help.
References
DelliFraine, J. L., Langabeer, J. R., & Nembhard, I. M. (2010). Assessing the evidence of Six Sigma and Lean in the health care industry. Quality Management in Health Care, 19(3), 211-225. https://doi.org/10.1097/QMH.0b013e3181eb140e
Langley, G. J., Moen, R. D., Nolan, K. M., Nolan, T. W., Norman, C. L., & Provost, L. P. (2009). The improvement guide: A practical approach to enhancing organizational performance (2nd ed.). Jossey-Bass.
Taylor, M. J., McNicholas, C., Nicolay, C., Darzi, A., Bell, D., & Reed, J. E. (2014). Systematic review of the application of the plan-do-study-act method to improve quality in healthcare. BMJ Quality & Safety, 23(4), 290-298. https://doi.org/10.1136/bmjqs-2013-001862
How this DNP 860 Module 5 example is structured
DNP860 Module 5 samples usually select an improvement model and justify it against alternatives. Aspen does not publish module deliverables, so check your classroom for the exact prompt. This example derives criteria from the evidence and setting, describes and evaluates three models with sources, makes and justifies a choice and states what the choice commits the project to.
DNP860 Module 5 questions, answered
What does DNP860 Module 5 usually ask for?
The module usually asks you to select an improvement model for your project, such as the Model for Improvement, Lean or Six Sigma, and justify the choice against alternatives. Aspen does not publish module deliverables, so your classroom's instructions govern.
What are the three questions of the Model for Improvement?
The questions ask what the team wants to achieve, how it will measure whether a change helped, and which changes are worth testing. Each change is then tried through plan-do-study-act cycles.
What is the difference between Lean and Six Sigma?
Lean focuses on eliminating waste and improving flow, while Six Sigma focuses on reducing variation and defects through the define, measure, analyze, improve and control cycle using statistical tools.
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