SIX SIGMA IN HEALTHCARE DELIVERY Matthew J. Liberatore, Villanova University, 610-519-4390, matthew.liberatore@villanova.edu ABSTRACT This paper reviews and assesses the extant literature on the application of six sigma in health care delivery, focusing on the areas of application, process changes initiated and outcomes, including improvements in process metrics, cost, and revenue. The reported six sigma applications were classified using a two-dimensional framework: area of application within health care delivery and key process metrics improved. The findings suggest that although six sigma has been effective in improving health care delivery, more emphasis needs to be placed on improving the process of identifying and evaluating alternatives, and verifying that the changes implemented offer significant and sustainable improvements. INTRODUCTION The United States continues to devote substantial amounts of its resources to health care. U.S. health care spending growth decelerated in 2008, increasing 4.4 percent compared to 6.0 percent in 2007. Hospital spending growth increased 4.5 percent to $718.4 billion compared to 5.9 percent growth in 2007. Health spending growth for state and local and private sources of funds also slowed while federal health spending growth accelerated in 2008. Total health expenditures reached $2.3 trillion in 2008, which translates to $7,681 per person and an increase to 16.2 percent of the nation’s GDP or Gross Domestic Product [132]. While health care spending continues to rise, so do concerns about health care quality. A major impetus toward recognizing the need to improve health care quality and patient safety occurred when the Institute of Medicine (IOM) released a report in November 1999 estimating that as many as 98,000 patients die as the result of medical errors in hospitals each year [65]. Through process and quality improvement efforts, the quality of health care for millions of Americans improved in 2007 but significant variations in performance continue to leave many people receiving substandard care [86]. The IOM report and the ongoing interest in improving operational cost and quality led a number of authors to recommend the application of six sigma to health care in the US and elsewhere [6] [21] [48] [60] [64] [68] [83] [92] [127]. Carrigan and Kujawa [16] states that six sigma is an effective strategy tool that can be used to establish and sustain competitive advantage and facilitate achievement of long-term strategic goals in health care. Physician participation is critical, and strategies to support their engagement are discussed in [42]. Some authors suggest that Six Sigma grew out of the total quality management (TQM) movement. TQM had a number of shortcomings, including not providing evidence of better patient outcomes, increased satisfaction, or improved financials. These factors, along with its inability to remove root causes of problems and demonstrate a strategic importance, led to TQM’s eventual decline. In contrast, Six Sigma offers time and money deliverables; the sigma metric to indicate the current state of process, outcome, or service quality; and a focus on improving the “critical to quality” (CTQ) characteristics vital to internal and external customers [11]. Woodard [143] describes evolution of quality control methods and compares them to six sigma, and ultimately advocates for six sigma. However, Landek [76] argues that six sigma is a useful tool that may not be effective in hospitals because of the cash and resources required. Neff (2003) states that six sigma can be overwhelming in scope if not broken down into manageable pieces, and requires significant investment in time. The purpose of this paper is to review and assess the extant literature on the application of six sigma in health care delivery, focusing on the areas of application, process changes initiated, and outcomes, including improvements in process metrics, cost, and revenue. Those areas that have seen the most successful application are identified, and suggestions for other application areas and improved usage of six sigma are discussed. OVERVIEW OF SIX SIGMA Six sigma is credited with helping Motorola win the Malcolm Baldridge Award in 1988. Six sigma is a process improvement goal that was developed by Motorola in the early 1980s and subsequently has been adopted by many organizations. Traditionally a capable process was one in which its natural variation of plus or minus three standard deviations, or sigma, from the mean was less than the target specifications. Under the assumption of normality, this translates to a process yield of 99.73 percent. Motorola's Six Sigma asks that processes operate such that the nearest target specification is at least plus or minus six sigma from the process mean. This translates into an error rate of 2 parts per billion. Often, an error rate of 3.4 parts per million is associated with Six Sigma quality, under the assumption that the process mean can shift 1.5 standard deviations on either side of the mean [80]. Six Sigma projects are undertaken to improve the process of interest, focusing on the CTQ. A structured approach is used to uncover the root cause of problems using the DMAIC (DefineMeasure-Analyze-Improve-Control) methodology: Define the problem within a process Measure the defects Analyze the cause of defects Improve the process performance to remove causes of defects Control the process to make sure defects do not recur. DMAIC is a data-driven process that uses various quality and process improvement tools that have been developed over time, including: statistical analysis, cause and effect diagrams (fishbone, Ishikawa), control charts, design of experiments, Pareto Analysis, process mapping, Failure Modes and Effects Analysis (FMEA), Quality Function Deployment (QFD)/House of Quality, and Suppliers, Inputs, Process, Outputs, and Customers (SIPOC diagrams), among others. Organizations that use Six Sigma emphasize employee participation and training through three levels: Green belts: individuals that have completed basic training and participate in Six Sigma projects Black belts: individuals competent to serve as on-site consultants and lead project teams Master black belts: individuals who have mastered the Six Sigma process and are capable of teaching it to others and acting as resources for project teams [35] [93]. Six sigma is sometimes combined with lean management, which is based on the principles of the Toyota Production System [141] [142], and the resulting method is called lean six sigma. A kaizen event may be used, which is a focused, intensive, short-term project targeted to improve a process. Jacobson and Johnson [67] argue that the combined implementation of lean and six sigma drives effective results in healthcare, when DMAIC and the lean principles of speed, efficiency, and immediate action are applied. Daley [28] addresses the most common misconceptions regarding lean six sigma using several mini cases to provide anecdotal evidence. LITERATURE REVIEW There are some studies that have attempted to assess the implementation of six sigma in health care. Martin and McLennan [82] surveyed health care organizations and found that six sigma was the most common approach utilized by nearly one in five (18.5%) of the respondents followed closely by lean processes (13.3 %). Antony et al. [6] include a summary of outcomes and financial savings from ten health care organizations having six sigma programs. Of the ten firms, six were able to estimate cost savings and/or revenue increases. Revere et al. [105] provide a summary of some six sigma applications, while Gras and Philippe [54] review the application of six sigma in some clinical laboratories. All of the specific applications mentioned in these reviews are included in our application review if sufficient information was found in either these or other articles. RESEARCH METHODOLOGY To identify those journal articles that describe the application of six sigma in healthcare, an extensive literature search was conducted. The research process used the keyword “six sigma,” in combination with the keywords “healthcare,” “health care,” and “hospital.” We searched Pub Med, ABI/Informs Proquest (business), Compendex (engineering), CINAL (The Cumulative Index to Nursing and Allied Health Literature), and PsycINFO using these keywords. The topics of the articles that were uncovered in the database searches were screened to determine if the six sigma methodology had either been recommended for application or actually applied in a health care context. Our search excluded conference proceedings and doctoral dissertations since we assume that important research will eventually appear in academic or professional journals. We also exclude non-English language publications from our search. Applications were included in this review if they provide sufficient details concerning the study approach, process changes initiated, and the results achieved, often including improvements in metrics. RESULTS Ninety-seven six sigma applications were identified, and address a variety of application within health care delivery, as shown in Table 1. At the highest level, area of application was defined to include inpatient care, therapeutic support, emergency care, ambulatory care, and administrative. Inpatient care includes the processes associated with the major flow of patients through a hospital or medical center, including admission, medical/surgical, critical/intensive care, hotel services, and discharge. For example, hospital admission and pre-registration processes and the time required to obtain subsequent treatment are areas that have been addressed using six sigma. These studies indicate that six sigma has been effective in improving admission-related processes, and is an area of application that might be considered by more hospitals. Table 1: Six Sigma Applications in Health Care Delivery Inpatient Admissions Registration process Pre-registration system Bed assignments for patients needing to be isolated Development of kidney transplant list Medical/Surgical Catheters: infection, UTIs, groin injuries, insertion Cardiac surgery infections Insulin, heparin, breast milk administration Correct blood transfusions Double stapling technique (surgical procedure) Incidence of falls pressure Medication errors, timing, compliance, usage CHF, COPD, Ventilator, Delivery Room LOS Surgery, OR TAT & productivity Pain management, nursing efficiency Intensive/critical care Ventilator days spent, incidence of pneumonia Transfer time to regular patient unit Compliance with hand hygiene regulations Hotel services/discharge/other TAT for bed assignment Time to complete patient discharge: routine, SNF, Medicare Centralized equipment delivery Removal of old inventory Unresolved work orders Therapeutic Support Laboratory TAT for ED laboratory orders TAT for MCI test Pneumatic tube system wait/travel time Laboratory requisition errors Phlebotomists’ efficiency Diagnostics/Radiology Defect rate of X-ray films Communicating findings without defects Test wait time Report creation time Stress test TAT Mammography screening cycle time Radiology scheduling process CT capacity Pharmacy Medication safety, errors In-hospital drug sales Pharmacy call backs to physicians Emergency Care Physician turnover Reduce patient “walk out” rate: improve flow; add capacity, reduce staff turnover Patient flow: throughput rate, LOS Door-to-doctor time Patient wait time for treatment Patient wait time for a bed Ambulatory Care Ambulance Best hospital destination, response time Home health Prospective payment system – process automation reduce low utilization payment adjustments use of telehealth device Outpatient/Surgical Clinics LOS for post-anesthesia and ambulatory surgery Medicine dispensing errors Patient access to OB/GYN clinic Delays in starting treatments for oncology patients Wait time from lab order placement to specimen collection Reduce rate of follow-up to new patient in Genitourinary Medicine clinics Administrative Billing/Employee Management Billing accuracy Number of invoice mistakes from temporary employment agencies Employee recruitment process time Employee vaccination rate Develop tool for staff effectiveness Figure 1 shows the number of reported six sigma applications over time. Note that the initial applications coincided with the publication of the IOM report. After a period a rapid growth, the number of reported six sigma applications has remained steady since 2004, the year when the first lean six sigma application appeared. Interestingly, the number of reported lean six sigma applications has remained at a steady level since 2005, perhaps indicating that those health care organizations that are adopting lean principles are not necessarily combining their efforts with six sigma. Figure 1: Reported Six Sigma Applications in Health Care Delivery Over Time 16 14 14 14 14 13 13 Count of Applications 12 12 10 12 12 10 9 8 8 8 8 7 6 6 4 4 4 4 2 0 1 1 0 0 2000 2001 1 0 2002 1 0 2003 2004 2005 2006 2007 2008 2009 Year Six Sigma Lean Six Sigma Total ANALYSIS To obtain a better understanding of the extent of successful Six Sigma implementation, the reported applications were classified using a two-dimensional framework: area of application within health care delivery (as described above) and key process metrics improved (Table 2). The second dimension, process metric, includes defect rate, medication error, process time, compliance rate, and productivity. We note whether data on the level of improvement of the metric(s) are provided, whether cost and revenue improvements were obtained, and whether the application is six sigma or lean six sigma. Focusing first on the rows in Table 2, we see that of the 97 applications reviewed, the health care delivery areas receiving the most attention are medical/surgical (33), diagnostics (14), and emergency care (11). These applications offer useful information and guidance to other health care organizations facing similar problems. A limited number of applications were found in inpatient areas such as admission, discharge, and hotel services, which should be amenable to six sigma process and quality improvement efforts. Also, limited applications were found in ambulatory care areas such as surgery and clinics, which face issues similar to those in the medical/surgical area. In addition, there were no reported applications in other support areas within the hospital such as respiratory therapy and rehabilitation, as well as in physician practices, an important area of primary care. These findings suggest that six sigma can see much more widespread application in health care delivery. Second, nearly all of the reported applications indicate the level of improvement of the key process metric after implementation. Only about one-third of the applications translate the level of process improvements into cost savings or revenue enhancement to demonstrate value and significance. The value of six sigma applications need to be clearly demonstrated to help maintain commitment to the process changes implemented. Along the same lines, only three of the applications discussed the sustained improvement in the key metrics. The control process is critical, so that the process and quality improvements are maintained. Six sigma focuses on reducing process variation and errors, so it is clear why over one-third of the reported applications have error rate (defect rate, medication errors, or compliance rate in Table 2) as their driving metric. Of the remaining applications, about one-third focus on process time (e.g., cycle time, TAT, LOS, wait time) and slightly less than one third focused on productivity (e.g., resource utilization, throughput, capacity) metrics. Selection of the key metric is a critical task that directs six sigma process improvement efforts. CONCLUSIONS In this paper we have reviewed the reported applications of six sigma in health care delivery and presented a two-dimensional framework that has categorized the applications by area and the metrics improved. Our research demonstrates that many health care organizations have reported the application of six sigma or lean six sigma. Across the reported health care delivery applications, DMAIC is widely used to implement six sigma, and a number of hospitals have utilized consultants, including GE Healthcare Systems. Over time, the number of reported six sigma applications has remained at a steady rate. Hospitals that have not implemented six sigma or lean six sigma can learn from the successful applications discussed in this paper. Table 2: The Six Sigma Applications in Health Care Delivery Literature Classified Using a Two‐Dimensional Framework Functional Area Defect Rate Medication Error Process Time Compliance Rate Productivity Total Inpatient Care C Admission C R Medical/ Surgical Intensive/ Critical [47**, 120], [33*], [84*], [27*, [109**], [9**], C 55*, 90**], [57**], [59***], [40** ], [77, 99, [116**], [88**], [29], [137**] 144], [37] C 52** ], [98**], [121**], [10 , [125 ], [25*], [102***] C 135 , 134 ], [95**] [4**], [69** ] [100**] Discharge [123**], [5*] 4 C [135** , 30 ,134], [32], C C [118**] CR [1** ], [109***], [122** , 41**, C C [115** , 58** ] C Hotel Services Other R [111**],[43* ], [46** ] C [44**], [50** ], [111**], C [73**], [140** ], [34**] [38**] C [12** ] C [110**] C [30 ], [78 , 117**] 33 4 1 3 3 Therapeutic Support C Laboratory C [75**], [91** ], [117**] 5 [106**], [128** ] R R C [79** , 119** ], [7** ], [19**], [71*], [139**], [117**, Diagnostics C C [23** ], [53**] C Pharmacy [97**], [17*] C 26* ], [8, [39** ] [104** ], [18*], [51**], [138**] C [85**] [61** ] 14 4 Emergency Care C [81**], [124**], [45**], [111* ], Emergency Care C R R 11 [24**], [74], [96*], [78** ] [63** ], [129** ], [113**] Ambulatory Care C Ambulance Operations Home Health [126** ] C C [37 ], [82** ] [108***] Surgical [62**] Clinic [19*] R [14** ], [66] [2**, 56**, 3], [107**, 26**] 1 3 1 5 Administrative Billing Employee Management C C 2 3 [117** ], [30 ] [117**] [72**], [91*] C Legend: []articles in brackets relate to the same applicatio n, *beginning o r ending metric, **beginning and ending metirc, ***beginning, ending and sustained metric, co st savings, R revenue generated, bo ld Lean Six Sigma applicatio n For those applications applying DMAIC, statistical analysis is sometimes used to identify the sources of process variation. Process and other changes typically are developed in response to the major drivers of variation, but are sometimes implemented without statistical or other proof that the change is valid. On the other hand, in some cases we have sufficient statistical power so that even miniscule differences of no practical value will be seen as significant. More attention needs to be directed to make certain that the changes implemented are of statistical and practice significance. Generally, mathematical, computer, or statistical modeling are not used to help identify the best course of action, or to predict the change in behavior before implementation. There are opportunities to increase the use of modeling to improve the analysis phase of DMAIC. Overall, six sigma has made important contributions in improving health care delivery, and should find increased application, often in conjunction with lean management. 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