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MEASURING MEDICATION ERRORS WITH SIX SIGMA
Lee Revere*, Assistant Professor, Decision Sciences,
School of Business and Public Administration
University of Houston-Clear Lake
Houston, TX 77058
Ken Black, Professor, Decision Sciences,
School of Business and Public Administration
University of Houston-Clear Lake
Houston, TX 77058
Six Sigma is a quality tool that may be used for measuring and monitoring medication errors. Six Sigma facilitates prioritizing improvement areas
and allocating resources. Project teams and healthcare executives can monitor progress, report successes, compare TQM projects, and benchmark
with other facilities. The application of Six Sigma streamlines the identification of TQM projects, the analysis of data, and the reporting process,
making TQM efforts even more successful. This paper discusses implementing Six Sigma to specifically reduce medication errors.
Public and private sector groups are demanding a reduction in medical errors. Government agencies, non-profit organizations, private-
interest groups, and external review boards are devoting resources to reduce errors nationwide. By 2003, the Department of Health and
Human Services (HHS) will have allocated $84 million for projects aimed at reducing medical errors (Gardner, 2002). The Institute
of Medicine (IOM) is developing data standards for collecting, coding and classifying adverse event data and errors data (IOM,
2002)a, and The Institute for Safe Medication Practices is focused on reducing medication errors
(ISMP, 2002). The Joint Commission on Accreditation of Healthcare Organizations (JCAHO) has also identified patient safety as a
major issue (JCAHO, 2002)b, and over forty percent of the JCAHO standards are related to patient safety (Torpy, 2002).
Medication errors are a component of medical errors that are receiving a lot of attention. Medication errors often result in
serious patient harm and/or death. A 1999 IOM report estimated medication errors accounted for 7,000 deaths per year
(Phillips et al, 2001). During 2000, 41,296 medication errors were reported by 184 U.S. hospitals to US Pharmacopeia (USP), a
national standards-setting organization; three percent of these (1,238) resulted in patient harm (Pallarito, 2002). In 1995, JCAHO
reviewed 1,541 adverse events with 178 directly related to medication errors. Eighty-one percent of the adverse events (excluding
patient suicide) resulted in death or loss of function to the patient (JCAHO, 2002)ab The Federal Drug and Alcohol Administration
(FDA) collected data on 5,366 medication errors during 1993-1998, of these 78 percent resulted in serious patient outcome or death
For over a decade, U.S. hospitals have been adopting and implementing various continuous quality improvement programs
which could, in theory, be used to reduce medication errors. In fact, eighty-nine percent of hospital organizations claim to have
organization-wide efforts for improving the medication use process (ISMP, 2002)b. Presumably, these medication error reduction
efforts have included such total quality management (TQM) tools as interdisciplinary project teams, flow diagrams, Pareto charts,
control charts, and measurement goals. However, as documented above, in spite of such efforts medication errors continue to be a
serious and costly problem for hospitals and have become a leading area of concern in on-going dialogue about healthcare safety. Six
Sigma is a quality movement that offers hope for significant improvement in the delivery of quality healthcare and in the reduction of
Six Sigma is a relatively new quality management tool that started in the late 1980’s at Motorola to accelerate the rate of change in the
competitive marketplace. It was greatly expanded upon and developed in the 1990’s at General Electric and Allied Signal/Honeywell
and has had a dramatic effect on the total quality management programs of many companies in the business world (Pande et al, 2000).
While Six Sigma has been highly successful in many industries, it is only just beginning to be implemented in healthcare. Six Sigma
has great potential for helping healthcare organizations provide higher quality service. Through Six Sigma, healthcare organizations
can measure, analyze, and reduce their number of adverse outcome events driving improvement in patient safety. In fact, healthcare
organizations operating at ‘Six Sigma’ have adverse event (defect) rates of 3 per million opportunities (Harry, 2000). Presumably, this
near-zero rate is acceptable to non-profit organizations measuring quality, private-interest groups interested in medical errors, external
reviewers monitoring medication error rates, as well as consumer and insurer customers.
While Six Sigma’s potential for reducing medication errors in the healthcare industry is great, few healthcare organizations
have implemented Six Sigma (Lazurus, 2002). Some of the more successful attempts at implementing Six Sigma into healthcare
include those at Charleston Area Medical Center, Mount Carmel Health, Scottsdale Healthcare, and Virtua Health. Charleston Area
Medical Center used Six Sigma to reduce the inventory of surgical equipment and related costs. Six Sigma led Mount Carmel Health
to redefine their billing standards. Scottsdale Healthcare was able to reduce the amount of time to find a bed and transfer a patient out
of the emergency room. Virtua Health improved patient satisfaction and reduced the length of stay for its congestive heart failure
patients by using the Six Sigma principles and tools. All of these organizations noticed improvements in their profitability, either
directly or through a reduction in length of stay.
Six Sigma can be an excellent managerial tool for monitoring and reducing medication errors because of its focus on
identifying, analyzing, and monitoring errors. Six Sigma is an approach that uses deep-level data measurement, collection, and
analysis; extensive employee education and training; and a philosophy that permeates the organization. “Six Sigma aims for the
optimal solution rather than what’s simply ‘good enough.’ It really takes traditional TQM efforts to the next level and has a great
future in healthcare” (Lazarus, 2001). Six Sigma’s measurement orientation and goal of obtaining only 3.4 errors per million
opportunities heightens quality efforts by quantitatively measuring goals, tracking progress, and providing a relative comparison rate.
SIX SIGMA AND TQM
Six Sigma does not have to replace other TQM efforts but rather can be used to complement, embellish, and strengthen such
programs. Six Sigma’s Failure Mode and Effect Analysis (FMEA) is used by team members to identify opportunities for failure, or
potential areas where medication errors may occur, and their effect on the patient and organization. This is analogous to TQM’s
multidisciplinary team approach to reducing medication errors. Using the medication processes defined by JCAHO (prescribe,
dispense, and administer) hospitals delineate failure opportunities available for each process. The quality management department
assists with data collection and reporting of medication errors. Errors are charted to better understand root causes, and a Six Sigma
level can be computed. The sigma level is used to compare medication processes, allocate resources, track progress, and report to
SIX SIGMA IMPLEMENTATION
In Six Sigma, a company’s sigma level for a given process can be computed through the use of a ratio of the number of errors to
number of opportunities for error. This ratio as it applies to medication errors is determined as:
Medication Error Ratio = Number of Medication Errors (1)
Number of Opportunities for Error
This ratio is used to compute the percentage of items “in compliance” which, in turn, is used to determine the sigma level. Defining
and determining the number of opportunities for medication errors is a critical part of this process.
The JCAHO categorizes medication errors into three areas. These include 1.) Prescription Errors, 2.) Dispensing Errors, and
3.) Administering Errors. Each hospital organization must define the opportunities for failure, or error, that can occur within each of
these three categories. This can be done using existing TQM teams and/or current literature. Current literature suggests prescribing
errors may include: drug knowledge deficit, miscalculation of dosage, poor oral communication, and poor written communication.
Dispensing errors may include: misinterpretation of order, name confusion, poor labeling, poor packaging and design. Likewise,
administering errors may include: wrong time, inappropriate dose (including omission), incorrect drug, improper route of
administration, and wrong patient (Phillips et al, 2001 and Mullins, 2002).
The denominator used in calculating sigma represents the total number of potential opportunities for failure within each
category. Thus, a different denominator will exist for each medication error category.
Once the TQM team has identified the total number of potential opportunities for failure, data collection efforts are necessary
to record anytime one of these failures (errors) occurs. The actual number of medication errors that occur within each category is the
numerator in computing the sigma level. Once the ratio of actual medication errors to opportunities for errors has been computed, a
Six Sigma chart is cross-referenced to obtain the actual sigma level (Harry, 2000).
Using the sigma levels, management can identify which area (prescribing, dispensing, or administering) is the largest
contributor to the overall number of medication errors. To better identify where to focus improvement efforts, traditional TQM tools
such as Pareto charts and control charts can be used to further investigate where the errors are occurring within each category.
Six Sigma is a new management tool that extends TQM medication error reduction efforts by seeking an almost non-existent error
rate. Sigma levels are easily computed using already collected data. The sigma level can be used to identify which area (prescribing,
dispensing, or administering) needs to be focused on first. Project teams, and healthcare executives, can measure success by
monitoring one indicator, the sigma level. The healthcare systems, as well as external organizations such as JCAHO, can use sigma
levels to equitably compare hospitals.
The implications of integrating Six Sigma with all of the existing TQM efforts are tremendous. This paper presents a
framework for including Six Sigma in an organization’s TQM plan and provides an example using medication errors. Extending Six
Sigma to other TQM projects is easily achievable. Using existing TQM teams and FMEA, opportunities for failure are identified. The
data that are currently being collected by the TQM team can be used as the failures. A quick mathematical computation yields the
error rate that is cross-referenced to the sigma level. Once determined, the sigma level can be used to monitor progress, report
successes, compare TQM projects, and benchmark with other facilities. The application of Six Sigma streamlines the identification of
TQM projects, the analysis of data, and the reporting process, making TQM efforts even more successful.
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