Rev Environ Health 2019; aop Original Article Selim Ahmed* Integrating DMAIC approach of Lean Six Sigma and theory of constraints toward quality improvement in healthcare https://doi.org/10.1515/reveh-2019-0003 Received March 25, 2019; accepted May 27, 2019 Abstract: Healthcare is a unique service industry and it deals with complex tasks. To overcome complex tasks, healthcare organizations need to implement DMAIC (Define, Measure, Analyze, Improve, Control) approach of Lean Six Sigma (LSS) to improve quality performance. Application of DMAIC in a healthcare organization provides guidelines on how to handle a quality service system toward patient satisfaction. This approach also helps healthcare service providers to reduce waste, variation and work imbalance in the service processes. This chapter discusses five phases of DMAIC approach and its integration with the theory of constraints (TOC) for continuous improvements in healthcare performance. The integration of TOC and DMAIC approach would enhance healthcare performance by reducing medical costs, medical errors, administration errors and defects. Moreover, this integration can improve performance in healthcare service processes where it is not possible to reduce bottlenecks. Keywords: DMAIC approach; healthcare; Lean Six Sigma; quality improvement; theory of constraints. Introduction In 1950s, the Lean Production System was introduced by Taiichi Ohno who worked at Toyota as an engineer. The purpose of this approach was to reduce waste and improve quality performance in production processing. This system was first implemented by the Toyota Company to enhance value-added activities and reduce non-value-added (NVA) parts in the automobile production process (1, 2). By introducing this approach, Toyota was able to beat Ford and *Corresponding author: Selim Ahmed, World School of Business, World University of Bangladesh, Plot – 3/A, Road – 4, Dhanmondi, Dhaka – 1205, Bangladesh, E-mail: [email protected]. https://orcid.org/0000-0002-0361-6797 became the second largest world car producer in 2004. After 2 years, Toyota profits increased to USD 12 billion, whereas Ford lost USD 12.7 billion and General Motors (GM) lost USD 3.4 billion (3). In 2008, Toyota beat GM and became the world’s greatest automobile producer. In 1990s, Xerox Corporation modified the Lean Production System as a Lean method and implemented it in their supply chain management process. In 2002, Xerox integrated Lean and Six Sigma methods together and named it “Lean Six Sigma (LSS)”. The main reason for this integration was to improve the quality production process by eliminating errors and reducing costs. Once the Xerox Corporation succeeded in implementing the LSS method in their production process, many healthcare organizations started to adopt this approach to improve their quality service toward patient satisfaction (4, 5). In addition, integration of Lean and Six Sigma approaches can improve the quality performance of the healthcare organization by increasing patient care toward satisfaction and loyalty. The LSS method ensures quality performance of the healthcare organization by reducing error in the medical test report, waiting time, costs and delivering test report (6, 7). According to De Koning et al. (8), the LSS method has a strong effect on developing innovative health service by reducing costs and errors such as the radiology department of Virtua Health reduced medication and laboratory errors and improved patient safety by implementing the LSS application. Similarly, the Commonwealth Health Corporation implemented the LSS approach in the project of the infection control group and they succeeded in reducing the infection rate by over 65% within a few years. The LSS approach not only reduces waste and costs but also establishes a culture of continuous quality improvement in a healthcare organization to ensure accurate outcomes in a timely fashion (9). Application of DMAIC in healthcare Application of DMAIC (Define, Measure, Analyze, Improve, Control) approach in a healthcare organization provides Brought to you by | La Trobe University Authenticated Download Date | 7/20/19 2:47 PM 2 Ahmed: Integrating DMAIC approach of LSS and TOC toward quality improvement in healthcare Define of the define phase is to analyze the project target and its duration. The define phase must confirm the understanding between the team and the management (10). Both the team and the healthcare management (sponsor) should: i Agree on the problem: what are the main issues that affect the patients, what are the main factors to determine the voice of the customers (VOC), how the present performance fulfil the desires of patients toward satisfaction; ii Understand the corporate strategy and its relationship with return on investment capital (ROIC); iii Agree on the limitations of the project; and iv Identify what indicators will be applied to measure the success of the healthcare organization. In the define phase, the top management of healthcare organization must clearly define the project objective and scope for the team according to the agreement. The top management needs to explain to the team “what the project is and what it should accomplish” to determine the needs of the customers (13). Precisely, the main task The abovementioned points are important in service organizations except the second point. When a process map is designed, the organization normally defines the project boundaries by identifying the starting and ending points on the project map (14). However, these LSS processes of mapping will not work if people issues are not guidelines on how to handle the organizational employees’ perspective of each phase toward better quality performance (10, 11). One of the key advantages of applying the LSS DMAIC process is that it prevents duplication process and continuously improves quality performance. Through the LSS approach, the organization’s employees and experts (i.e. Black Belt and Green Belt holders) will understand why both Lean and Six Sigma are necessary to maximize organizational performance (12). Figure 1 shows the LSS DMAIC process tools followed by a detailed discussion. Define Measure Analyze Project selection tools PIP management process Value stream map (VSM) High level process map Financial analysis Project charter Stakeholder analysis Kano analysis Communication plan Voice of customer (VOC) Operational definitions Data collection plan Pareto chart Histogram Box plot Statistical sampling Measurement system analysis Control charts Process cycle Process performance Pareto charts Cause & Effect (C&E) matrix Fishbone diagrams Brainstorming Constraint identification Time trap analysis Non-value-added analysis Hypothesis testing Confidence intervals Analysis of variance Queuing theory Improve Benchmarking TPM (total productive maintenance) Line balancing Process flow improvement Setup reduction Generic pull 5S Kaizen Poka-Yoka Solution matrix Control Control charts Standard operating procedures (SOPs) Project commissioning Visual process control Mistake-proofing Process control plans Training plan Project replication Plan-Do-Check-Act (PDCA) cycle Figure 1: Lean Six Sigma DMAIC process tools. Brought to you by | La Trobe University Authenticated Download Date | 7/20/19 2:47 PM Ahmed: Integrating DMAIC approach of LSS and TOC toward quality improvement in healthcare defined properly. Two people issues must be defined in the define phase, such as: i The project leader must ensure that the right team members are in the team. The team members should not only be assessed by knowledge, experience and training but also evaluated by their attitude and performance. ii The project leader must ensure that all team members are engaged in the project. The team members should start their project activities from the same page with the same expectations. The more the team members deliberately participate in the project and understand the importance of the project work, easier it will be to complete it (10). The project leader of the LSS program should develop a communication plan to provide information to the top management of the organization and receive feedback on the progress and direction of the project. It is very important for the project leader (Black Belt or Green Belt Champion) to often meet the project owner or top management to inform about the project results and processes (11). The project leader should inform the project owner early if any changes have been made in the project. The feedback of the project owner would provide direction which will facilitate the project’s success and implementation without complexity (15). Measure In this step, the measureable service indicators are identified according to the operational definition of critical to quality (CTQ). This phase also identifies the input and outcome measurements such as conducting process level data collection, establishing baseline metrics, logically placing array data in visual depictions and following statistical rigor: sampling and reporting (13). The measurement comprehends the VOC and then translates the customer feedback into measurable design requirements. The emphasis on VOC could be novel for those accustomed to DMAIC projects. Although customer needs shape the priorities in a DMAIC project, VOC analysis emphasizes an accurate understanding of the customer needs as a vital determinant of success (16). To understand the VOC, the team should measure the value stream mapping (VSM) through: i Data collection plan; ii Current and future state map; iii Determine specs for CQT; iv Use histograms to characterize the variables that could cause the quality issue under consideration; and v 3 Use variables search, scatter plots, response surface methodology, Pareto charts or measurement check sheets to focus attention on the vital few contributors to the quality issue. Unfortunately, it was observed that many people in service organizations have misused data and statistics to justify false arguments. Therefore, the project leaders should be involved in data collection and processing. They should ask the team members to decide what types of data should be collected and why, and how it will be used to measure the customers’ needs (10). Analyze This step analyzes the collected data and uses VSM to identify and validate the causes of errors that affect the NVA processes (17). This phase analyzes the information collected in the measurement phase to identify the sources of delays, waste and poor quality. In our analysis, we use Pareto diagram, cause-and-effect diagrams, scatter plots, design of experiments and 5 Whys analysis as part of our LSS approach to map and explore the causeand-effect relationships (13). In the analysis phase, the LSS team discovers problems in the service processes and determines the valueadded or NVA work for the customers. The value process can be classified into three different categories: i Customer value added (CVA): CVA only focuses on customers’ value; ii Business value added (BVA): Despite being useful for businesses, customers do not derive value from this category; and iii Non-value added (NVA): It is an activity which has no value from the customers’ viewpoint (18). In most service processes, work such as calls, forms and requests spends only 5% of its time in value-add and the remaining 95% is spent for waiting around, being reworked and so on. If the organization increases 20% value-add work, then it will reduce 20–50% NVA work and costs of the project. A well-trained Black Belt champion can identify the problems in service processes and facilitate a team through a VSM event to determine the steps of value-added and NVA work for the customers (16). Improve In this phase, the LSS project team eliminates the root causes of defects which have influenced the CTQ process Brought to you by | La Trobe University Authenticated Download Date | 7/20/19 2:47 PM 4 Ahmed: Integrating DMAIC approach of LSS and TOC toward quality improvement in healthcare (13). More importantly, the improve phase makes changes in the service processes by eliminating the defects, waste and costs related to the customer needs as identified in the define phase. This phase uses common tools and strategies to select the best alternatives to meet the customers’ needs. To select the best alternatives, the team must use the solution matrices tool, because it has a relationship with brainstorming solutions, project purpose and methods to meet customer needs (14). After selecting the best alternatives for customer needs, the project leader should pay attention to the implementation processes such as: i The project leader should focus on project activities closely and if there is anything wrong, the project leader will immediately stop the process of the project activity. Then, the project leader will figure out why those problems occurred, and how it will be eliminated to avoid delays or interruptions in the improvement process; ii Implement an action plan for eliminating the quality issue; and iii Plan a strategy for the removal of restraining forces and the subtle promotions of driving forces. However, nothing will be changed in the improve phase if the project leader does not pay attention to people issues, especially communication with team members, team involvement and commitment. Team members could be used as a sample to represent the larger group of people who work on that process. Their work could be facilitated by clear and regular communication with co-workers that would support the achievement of the targeted goals. They could share potential solutions, provide constructive feedback on the work of colleagues and ask for help. The concept of Kaizen can help define work tasks and measure the extent to which they are being achieved. It supports effective team work and proactive communication for enhanced work performance (16). Control The control phase aims to achieve sustainable solutions. Achieving this involves improving and controlling the variables critical to process performance and tracking the LSS process performance (19). The project team should share their knowledge with others who will resume their task and ensure that all members are working on the same set of updated procedures. There are six important issues of control in the service environment which must be followed by the team to ensure improved process performance (20, 21). These are: i ii Ensure the improve process is recorded; Turn the outcomes into cash (verified by the finance division); iii Maintenance of improvements must be confirmed during the working process; iv An automated monitoring system must be set up to identify “out of control” performance; v Organize the working process; and vi Create a control plan. According to Carreira and Trudell (18), a control process plan usually builds on the future state process map, indicating who is responsible for what is in the new process. Therefore, the LSS team must keep in mind the causes of the potential problems that could arise during the elimination of quality issues, and using control charts could help monitor the variations of the potential problems. Besides using the control chart, the team also needs to implement the control plan by observing the statistically significant variations and train the service operators to run the integrated quality control (QC) system effectively, and give them authority to make decisions during the service process (22, 23). Integrated theory of constraints and LSS The theory of constraints (TOC) was originally developed by Eliyahu M. Goldratt. It is a management philosophy that focuses on continuous improvement processes (24). The constraint is defined by Goldratt and Cox (25) as that which prevents a system from performing at the higher level than it currently does. TOC provides guiding principles and concepts which are supported by a set of logistical approaches to handle work processing flow through the system. It uses logical tools to identify system constraints and design and implement effective ways to improve the work processing systems (26). The fundamental assumptions of TOC include system thinking that views enterprises as a complete and complex system with interacting constituent parts. It regards constraints as an obstacle in the system that undermines peak performance and that there must be at least one such constraint in the system (25). According to Choe and Herman (24), TOC seeks to identify and address the constraint in the system to enhance the performance and facilitate the achievement of organizational goals. Choe and Herman (24) suggested that the organizational managers or top management need Brought to you by | La Trobe University Authenticated Download Date | 7/20/19 2:47 PM Ahmed: Integrating DMAIC approach of LSS and TOC toward quality improvement in healthcare These five steps of TOC are related to the Lean processing system which focuses continuously on quality improvement in the management processing systems of the organization (28). The TOC can be used to improve the Lean processing processes by eliminating bottlenecks (29). It is a tool that has had proven success in management processes, inventory and supply chains, project management and decision-making, among others (30). According to Breen et al. (31), TOC offers a logical and rigorous approach for analyzing and improving the performance of a healthcare organization. This theory has been applied in a number of areas in healthcare both in the United States and the United Kingdom to improve quality processing systems (31). Figure 2 illustrates the integration of LSS and the TOC model. According to Lepore and Cohen (32), TOC has a significant relationship with the LSS approach when it comes to improving the workforce management toward quality performance of the organization. The integration of TOC and the LSS approach enhances healthcare human resource management practices, such as human resource planning and management, training, employee recognition and job satisfaction. This integration helps healthcare organizations in reducing medical costs, medical errors, to determine what types of constraint tools will be used in the system processing for achieving the organizational goals at the earlier step in improving a system. They also mentioned that constraints can be divided into two parts of the processing system: physical and nonphysical. Physical constraints are often easier to address compared to nonphysical constraints which are hard to identify and resolve. Dettmer (27) defined constraints as a set of tools that change agents to increase organizational profits. Dettmer also stated that the existence of constraints provides an excellent opportunity for improvement of the organizational performance, because it allows the organizational processing system to highlight the most productive area through identifying and managing the constraints. There are five steps of TOC which would help the organization improve organizational processing. These are: i Identify the system’s constraint; ii Decide how to exploit it; iii Subordinate/synchronize everything else to the above decisions; iv Improve the system’s constraint; and v Return to step one, but beware of “inertia”. If the constraint has moved in the above steps, go back to step one. TOC Identification constraints Define If breaks, repeat Clinical coding Exploit constraints Cycle time in inpatient and outpatient diagnostic Patient waiting time Control Elevate Technical requirements Revenue cycle Billing process Lean Six Sigma Patient satisfaction Improve Measure Patient registration Medical costs Employee retention Defects Administration errors 5 Medical errors Analyze Subordinate Figure 2: Integration of Lean Six Sigma DMAIC method and TOC model in healthcare. Brought to you by | La Trobe University Authenticated Download Date | 7/20/19 2:47 PM 6 Ahmed: Integrating DMAIC approach of LSS and TOC toward quality improvement in healthcare administration errors and defects toward patient satisfaction and loyalty. This integration also helps healthcare organizations to recruit the best person for the job who possesses the skills and traits to perform the assigned tasks efficiently and exercise leadership. Such a person is key to quality improvement in healthcare service (33, 34). Grida and Zeid (35) conducted a study on the implementation of the TOC in Dar El-Shifa Hospital, Egypt. Their research objective was how TOC assumptions improve healthcare system by reducing waiting time in the operating room. Based on their study, it was observed that the implementation of TOC model helped the hospital to reduce the waiting time by 88%. This model also helped the hospital to improve the overall performance of the healthcare system by 6% and increase the doctor availability by 40%. Sahraoui and Elarref (36) conducted a study to reduce bed crisis and late cancellation of elective surgery in Hamad General Hospital, Doha, Qatar by applying five steps of TOC. Their research findings indicate that the TOC approach helps the hospital in analyzing the healthcare system and finding better solutions to reduce bed crisis and cancellation of elective surgeries. Pawlak (37) applied TOC techniques to eliminate the shortage of nurse workforce in the United States. According to her research findings, it was observed that TOC techniques help increase the availability of nurses in the hospital along with commitment. Discussion and conclusion Hospitals are highly concerned with the quality performance of their healthcare systems. To this end, they have incorporated quality techniques such as plan-do-studyact (PDCA), 5S, Kaizen, control charts and root cause analysis to achieve greater patient satisfaction (38). Studies on healthcare performance have explored the various ways to measure quality performance. This requires clearly defined performance outcomes with quantifiable measurements (39). Based on the assumption that quality performance reflects good-quality practices, in addition to the highly competitive nature of healthcare, hospitals are always seeking ways to improve their performance and increase patient satisfaction (38). However, with the complexity of healthcare, its highly specialized nature of many of its processes, the many staff and broad scope of its activities, it becomes difficult to measure quality performance (40). One of the difficult tasks to measure healthcare performance is the attribution variability associated with a high level of cognitive reasoning, problem solving, flexible decision-making and experiential knowledge (41). It is also hard to ascertain whether small mistakes were near misses or could have caused significant harm (42). To overcome the difficulties, the LSS and TOC model need to be integrated to enhance value-added activities toward quality performance in healthcare organizations. This integration not only increases the value-added activities but also reduces NVA activities (i.e. waste and unnecessary services) for the continuous improvement in healthcare quality performance (30). The DMAIC and TOC approaches depend on root cause analysis to investigate waste and errors within organizational processes. They support quality performance by eliminating waste and errors (43). In healthcare organizations, they support improvements in service quality performance. This integration also improves organizational human resource management practices such as recruiting the most appropriate person for the job who ensures that the tasks of the organization are executed as intended. This is vital for quality improvement (44). The present study mapped DMAIC with TOC assumptions to enhance the performance of the healthcare organization. However, due to less number of publications in peer-reviewed journals, it is required to conduct more research on DMAIC and its integration with TOC model to contribute theoretical knowledge as well as practical implications. For theoretical contribution, a common definition needs to be developed to distinguish between DMAIC and TOC for strengthening the existing literature. This study provides needful information to define both the approaches with examples. In addition, this study also provides the appropriate guidelines on how to analyze a healthcare system by integrating DMAIC and TOC approaches toward quality performance. For practical implications, the healthcare organization needs to obtain commitment and involvement of professionals for successfully implementing the DMAIC and TOC models. The implementation of these two approaches would help the healthcare organization to analyze healthcare performance such as patient safety, financial outcomes, patient satisfaction and loyalty (45, 46). Finally, from a strategic point of view, the integration of DMAIC LSS method and TOC model links internal and external performance of the healthcare organization. This integration not only provides insights to practitioners about the blueprint of the DMAIC and TOC for the continuous improvement of healthcare quality performance, but also creates a unique competency that may be difficult for competitors to duplicate. It is essential that the top management of the healthcare service providers should spend Brought to you by | La Trobe University Authenticated Download Date | 7/20/19 2:47 PM Ahmed: Integrating DMAIC approach of LSS and TOC toward quality improvement in healthcare time to understand both the applications and incorporate these models into management oversight and strategic planning for continuous improvement. When it is done properly, both approaches can increase the value of the healthcare services by improving quality performance. Research funding: None declared. Conflict of interest: Authors state no conflict of interest. Informed consent: Not applicable. Ethical approval: The conducted research is not related to either human or animal use. References 1. Chiarini A, Baccarani C, Mascherpa V. Lean production, Toyota Production System and Kaizen philosophy: a conceptual analysis from the perspective of Zen Buddhism. TQM J 2018;30(4):425–38. 2. Dahlgaard JJ, Mi Dahlgaard-Park S. Lean production, Six Sigma quality, TQM and company culture. TQM Mag 2006;18(3):263–81. 3. Chalice R. Improving healthcare using Toyota lean production methods: 46 steps for improvement. Milwaukee, WI: ASQ Quality Press; 2007. 4. Ahmed S, Abd Manaf NH, Islam R. Measuring Lean Six Sigma and quality performance for healthcare organizations. Int J Qual Serv Sci 2018;10(3):267–78. 5. Salah S, Rahim A. The integration of Six Sigma and Lean. In: An Integrated Company-Wide Management System. Cham: Springer, 2019;49–93. 6. Antony J, Palsuk P, Gupta S, Mishra D, Barach P. Six Sigma in healthcare: a systematic review of the literature. Int J Qual Reliab Manage 2018;35(5):1075–92. 7. Trzeciak S, Mercincavage M, Angelini C, Cogliano W, Damuth E, Roberts BW, et al. Lean Six Sigma to reduce intensive care unit length of stay and costs in prolonged mechanical ventilation. J Healthc Qual 2018;40(1):36–43. 8. De Koning H, Verver JP, van den Heuvel J, Bisgaard S, Does RJ. Lean Six Sigma in healthcare. J Healthc Qual 2006;28(2):4–11. 9. Neufeld NJ, Hoyer EH, Cabahug P, González-Fernández M, Mehta M, Walker NC, et al. A Lean Six Sigma quality improvement project to increase discharge paperwork completeness for admission to a comprehensive integrated inpatient rehabilitation program. Am J Med Qual 2013;28(4):301–7. 10. Maleyeff J, Campus H. Improving service delivery in government with Lean Six Sigma. Washington, DC: IBM Center for the Business of Government, 2007. 11. Momani A, Mumani A. Improving employees’ safety awareness in healthcare organizations using the DMAIC quality improvement approach. J Healthc Qual 2017;39(1):54–63. 12. Kovach JV, Curiel V, Franklin York A, Bogard S, Revere L. Enhancing information sharing in family drug courts: a Lean Six Sigma case study. Juvenile Fam Court J 2017;68(3):27–41. 13. Yeh HL, Lin CS, Su CT, Wang PC. Applying Lean Six Sigma to improve healthcare: an empirical study. Afr J Bus Manage 2011;5(31):12356–70. 7 14. Srinivasan K, Muthu S, Devadasan SR, Sugumaran C. Six Sigma through DMAIC phases: a literature review. Int J Product Qual Manage 2016;17(2):236–57. 15. Pojasek RB. Lean, Six Sigma, and the systems approach: management initiatives for process improvement. Environ Qual Manage 2003;13(2):85–92. 16. George A, Joseph AM, Kolencherry S, Kodath VV, Menaka K, Duraisingh B, et al. Application of Six Sigma DMAIC methodology to reduce medication errors in a major trauma care centre in India. Indian J Pharm Pract 2018;11(4):183. 17. Maynard KJ, Curri EJ, Washburn S. Patient Experience Project (PEP): understanding the patient experience to enhance patient satisfaction and care using the DMAIC process. J Oncol Navig Surviv 2016;7(9):31–2. 18. Carreira B, Trudell B. Lean Six Sigma that works: a powerful action plan for dramatically improving quality, increasing speed, and reducing waste. New York, NY: AMACOM/American Management Association, 2006. 19. Walters LM, Barneva R. Drilling the data: students use Six Sigma DMAIC to improve dental practice inventory management. BRC Acad J Educ 2017;6(1):57–74. 20. George M. Lean Six Sigma: Combining Six Sigma Quality with Lean Speed. New York: McGraw-Hill, 2002. 21. George ML, George M. Lean Six Sigma for service: how to use Lean speed and Six Sigma quality to improve services and transactions. New York: McGraw-Hill, 2003. 22. Devane T. Integrating Lean Six Sigma and high-performance organizations: leading the charge toward dramatic, rapid, and sustainable improvement. John Wiley & Sons, 2004. 23. Kuwaiti AA, Subbarayalu AV. Reducing patients’ falls rate in an Academic Medical Center (AMC) using Six Sigma “DMAIC” approach. Int J Healthc Qual Assur 2017;30(4):373–84. 24. Choe K, Herman S. Using theory of constraints tools to manage organizational change: a case study of Euripa labs. Int J Manag Organ Behav 2004;8(6):540–58. 25. Goldratt EM, Cox J. The Goal, Croton-on-Hudson. NY: North River Press Inc., 1984. 26. Dettmer HW. Goldratt’s theory of constraints: a systems approach to continuous improvement. Wisconsin: ASQ Quality Press, 1997. 27. Dettmer HW. Breaking the constraints to world-class performance. Wisconsin: ASQ Quality Press, 1998. 28. Nelson B, Sproull B. Epiphanized: a novel on unifying theory of constraints, Lean, and Six Sigma. New York: Productivity Press, 2015. 29. Rattner S. What is the theory of constraints, and how does it compare to Lean Thinking? Lean Enterprise Institute. Available at: http://www.lean.org/common/display/?o=223; 2006. 30. Rajini J, Nagaraju D, Narayanan S. Integration of lean, Six Sigma and theory of constraints for productivity improvement of mining industry. Int J Product Qual Manag 2018;24(3):424–40. 31. Breen AM, Burton-Houle T, Aron DC. Applying the theory of constraints in health care: Part 1 – the philosophy. Qual Manage Healthc 2002;10(3):40–6. 32. Lepore D, Cohen O. The theory of constraints and the system of profound knowledge. Great Barrington, MA: North River Press Publishing Co., 1999. 33. Gowen III CR, Mcfadden KL, Hoobler JM, Tallon WJ. Exploring the efficacy of healthcare quality practices, employee commitment, and employee control. J Oper Manage 2006;24(6):765–78. Brought to you by | La Trobe University Authenticated Download Date | 7/20/19 2:47 PM 8 Ahmed: Integrating DMAIC approach of LSS and TOC toward quality improvement in healthcare 34. Gowen III CR, McFadden KL, Settaluri S. Contrasting continuous quality improvement, Six Sigma, and lean management for enhanced outcomes in US hospitals. Am J Bus 2012;27(2):133–53. 35. Grida M, Zeid M. A system dynamics-based model to implement the theory of constraints in a healthcare system. Simulation 2018:1–13. 36. Sahraoui A, Elarref M. Bed crisis and elective surgery late cancellations: an approach using the theory of constraints. Qatar Med J 2014;1:1–11. 37. Pawlak R. Theory of constraints: what can we learn to support the nursing workforce? J Nurs Admin 2016;46(11):558–60. 38. Hughes RG. Tools and strategies for quality improvement and patient safety. In: Hughes RG, editor, Patient safety and quality: an evidence-based handbook for nurses. Rockville, MD: AHRQ Publication, 2008. 39. Varkey P, Reller MK, Resar RK. Basics of quality improvement in health care. Mayo Clin Proc 2007;82(6):735–9. 40. Ferlie E, Fitzgerald L, Wood M, Hawkins C. The nonspread of innovations: the mediating role of professionals. Acad Manag J 2005;48(1):117–34. 41. Lee JL, Chang BL, Pearson ML, Kahn KL, Rubenstein LV. Does what nurses do affect clinical outcomes for hospitalized patients? A review of the literature. Health Ser Res 1999;34(11):39–45. 42. Asch SM. Developing a clinical performance measure. Am J Preven Med 1998;14(3):14–21. 43. Khanchanapong T, Prajogo D, Sohal AS, Cooper BK, Yeung AC, Cheng TC. The unique and complementary effects of manufacturing technologies and lean practices on manufacturing operational performance. Int J Prod Econ 2014;153:191–203. 44. Laureani A, Antony J. Leadership and Lean Six Sigma: a systematic literature review. Total Qual Manage Bus Excel 2019;30(1–2): 53–81. 45. Bauer JM, Vargas A, Sellitto MA, Souza MC, Vaccaro GL. The thinking process of the theory of constraints applied to public healthcare. Bus Process Manage J 2019. DOI: https://doi. org/10.1108/BPMJ-06-2016-0118. 46. Gupta N, Lteif A, Creo A, Iqbal AM, Pittock S, Tebben PJ, et al. Improved utilization of waist-to-height ratio in cardiometabolic risk counselling in children: application of DMAIC strategy. J Eval Clin Prac 2019;25(2):300–5. Brought to you by | La Trobe University Authenticated Download Date | 7/20/19 2:47 PM
