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QC Planning for Pathologists in Training or in Practice[This internet course is under development by Rakesh Sarda, MD, and James O. Westgard, PhD. The course is a resident project that is part of a training rotation in the Clinical Laboratories at the University of Wisconsin Hospital & Clinics, where training in clinical pathology is under the direction of Patrick Buckley, MD, PhD, and Karl Voelkerding, MD, the clinical laboratory is directed by Arthur Eggert, PhD, and the Chairman of Pathology and Laboratory Medicine is Michael Hart, MD.] |
IntroductionSimply put, a good quality control (QC) program assures you, the pathologist, as well as your clinicians and ultimately your patients, that the test results from your laboratory are consistently reliable.
Many pathology residents pass through their training only marginally aware of the constant background hum of QC because a good QC program makes little "noise." Pathologists new to their jobs are often confronted with situations that are unexpected, that they are ill-trained for, and sometimes resentful of (as reflected by the comment "Dammit, Jim, I'm a diagnostician, not a statistician" when confronted with a laboratory QC problem").
But a quiet QC program also has its benefits. Once established, it runs itself with minimal daily intervention, thus letting you get back quickly to your microscope. Reliable results are assured for your patients, and you are not being interrupted frequently by your technologists with what might be called "weird results" or by your clinicans with complaints about "what the hell is going on down there in the lab."
A physician calls you to discuss his/her impression that the recent results for Hemoglobin A1C testing from your laboratory do not seem to correlate with what they would expect clinically.
A Clinical Pathway Team asks you to help them decide what change in Hemoglobin AlC would be medically important and could be reliably measured in your laboratory.
New recommendations or guidelines have been published on the optimal clinical use of Hemoglobin AlC and you want to be sure the performance of your laboratory method is good enough for this more demanding application.
Your hospital purchasing agent asks you to define the performance specifications for a new instrument that will be used to measure Hemoglobin AlC in a clinic laboratory.
One of your technologists wants your help to decide what precision and accuracy is acceptable for Hemoglobin AlC and how much QC is necessary for the new instrument you have just acquired.
As a Laboratory Director, you have to satisfy the CLIA guideline 493.1407 that says you must "ensure that the test methodologies selected have the capability of providing the quality of results required for patient care; " "ensure the establishment and maintenace of acceptable levels of analytical performance for each test system," and "ensure that the quality control and quality assurance programs are established and maintained to assure the quality of laboratory services and to identify failures in quality as they occur."
As the Director of Laboratories, the CAP checklist requires that "the quality control program clearly define goals for monitoring analytic performance, procedures, policies, tolerance limits, corrective action and related information" [CAP General checklist, Question 01:3000, phase II deficiency]
As Director of the Clinical Chemistry section, the CAP inspector asks to see your "document for the design and evaluation of the laboratory quality control (QC) program." [CAP Chemistry checklist, question 03:2000, phase II deficiency].
Hospital accreditation by the Joint Commission requires that "the laboratory ensures that quality control results meets its criteria for acceptability before it reports patient test results" [1998-99 JCAHO standard QC1.5].
As a pathologist, you have a critical role in assuring that proper QC procedures are in place in your laboratory. That means you will be expected to:
This course will introduce you to a quantitative QC planning approach and some quantatitive QC planning tools that are important for analytical quality management.
The course is intended to help you establish a systematic way, or quantitative process, for deciding what amount of QC needs to be done to assure the quality required in your laboratory, taking into account the performance observed for the methods in use in your laboratory.
Specifically, the purpose is to help you select the appropriate statistical control rules and the appropriate number of control measurements that will guarantee the analytical quality you have defined as necessary for the tests performed in your laboratory.
The course does not describe how to do QC, but assumes some basic QC background and provides some links for review of basic QC practices. It also assumes some knowledge of method evaluation practices, and in the future, will include some links for review of basic method evaluation experiments and the statistical analysis of that data.
We don't expect to cover everything you need to know about analytical quality management or even quality planning in this course, but rather will focus on a few critical objectives. After completion of this course, you should be able to:
This Course Description contains links to Lesson Outlines, which in turn contain links to the materials for each lesson. This web-page provides a convenient bookmark and guide for the course.
Lesson Outlines describe the objectives for each lesson, provide links to the web-materials to be used, and provide suggestions for assessment. It is suggested that these assessment questions be the starting point for discussions between the resident and a faculty mentor.
Lessons, Essays, and Example Applications that are accessed through the links provided in the Lesson Outlines may be printed for study and later reference.
QC Validator computer program, version 2E (educational), is available by download from the website. Please contact Dr. Westgard to obtain a password [e-mail jo.westgard@hosp.wisc.edu, telephone (608)263-1498, fax (608)263-1568]. This educational version has a ninety day time of use control. The manual and automatic features are fully functional, but there is no capability to print graphs, charts, or reports. Note: the QC Validator program is intended for PC's (386 or higher processors) operating under Windows 3.x or higher or Windows 95.
Computer tutorials are available to learn the operation of the QC Validator program and can be downloaded from this website.
Glossary of Terms provide convenient reference to the many terms that are part of the language of QC and this course of study.
Reference List identifies the scientific papers that are the basis of the approach and the main references for the course materials.
Lesson 1: Is analytical quality still an issue in laboratory tests? In Myths of Quality, Dr. Westgard challenges current thinking that analytical quality is better than needed for medical care. He sets out the objective of developing a quantitative quality planning approach to guarantee that laboratory testing process will achieve the necessary quality in routine service. In Understanding Quality, Jerry Ehrmeyer discusses the relative nature of quality and the need for "standards" of quality to compare and judge quality.
Lesson 2: How do you manage quality? In Assuring Quality through Total Quality Management, Dr. Westgard describes a framework for defining and implementing a quality management process that provides continuous quality improvement. This framework shows the synthesis of quality laboratory processes, quality control, quality assessment, quality improvement, and quality planning into a process centered on and guided by quality requirements. The impact of laboratory regulations on quality management is discussed by Dr. Sharon Ehrmeyer in her update on What's New with CLIA'88, JCAHO, and CAP.
Lesson 3 (Optional):
Do you want to review basic statistical QC practices?
In QC - The Idea, Dr. Westgard describes
the basic concept and terminology of QC. QC - The Practice
provides an overview of the entire process of planning,
implementing, and operating statistical QC procedures in laboratories,
and provides links to more detailed materials. Internet
Tools for QC Training gives you access to a suite
of interactive tools for calculations, plotting, simulation, training,
and checking QC data. (Revised 11/99).
Lesson 4: What quality is needed for a laboratory test? In The Need for Standard Processes and Standards of Quality, Dr. Westgard discusses different terms and characteristics that are used to describe quality and provides a systems perspective to show the relationship between these different characteristics. Per Hytloft Petersen provides a review of approaches to setting analytical quality specifications in his discussion of European Approaches to Analytical Goal-Setting. Summary tables are provided for available CLIA analytical total error criteria, clinical decision interval criteria, and European biological goals. (Revised 11/99).
Lesson 5 (Optional): Do you want to review basic method evaluation practices? QC planning requires estimates of the imprecision (random error, standard deviation, coefficient of variation) and inaccuracy (systematic error, bias) of a method. These estimates are initially obtained from method evaluation studies. Resources and materials for method evaluation are provided in this lesson.
Lesson 6: How do you build quality into a laboratory testing process? In Mapping the road to analytical quality with charts of operating specifications, Dr. Westgard outlines an 8 step quality planning process that starts with the definition of the quality required for a test, accounts for the observed imprecision and inaccuracy of the method, then leads to the selection of appropriate QC procedures and an appropriate Total Quality Control strategy. This planning process is based on quality-planning models, which are described here in terms of "error budgets" that can be graphically displayed in the form of charts of operating specifications (or OPSpecs charts). These OPSpecs charts provide "maps" that can be used to locate the performance of your method and determine what QC is needed. Based on the available capabilities of the statistical QC procedure, you can then establish the appropriate mix of statistical and non-statistical components in your overall QC system, as described in Total Quality Control Strategies.
Lesson 7: How can you do QC planning? In Tools and Technology for QC Planning, Dr. Westgard traces the history of QC planning and describes practical QC planning tools, such as power function graphs, critical-error graphs, and OPSpecs charts. The QC Validator computer program is introduced as an example of the kind of computer technology that can make these graphical tools readily available. An educational version of the program (QC Validator 2E) can be downloaded to provide these tools for use during this course. A demo of the program can be downloaded from the website and viewed to illustrate QC Validator's use. Detailed tutorials are also available via download from the website. FAQs about QC Validator provides additional discussion of the use and application of this computer program.
Lesson 8 (Optional): Do you want to learning more about QC planning tools? This lesson provides a more in-depth discussion and a more quantitative treatment of power function graphs, critical-error graphs, OPSpecs charts, and quality-planning models. If you aren't satisfied with just learning how to use QC planning tools, but want to understand where they came from and why they work, this lesson provides the materials and references to papers in the scientific literature.
Lesson 9: Applications - How do you assess the performance of a recommended QC procedure? In The Myth of Medical Decision Limits, the practice of using clinical and fixed control limits is evaluated. The QC planning process is used to first figure out what the actual statistical control rule is, then to evaluate that rule's performance based on its error detection and false rejection characteristics. A Glucose Point-of-Care application illustrates the proper approach for designing a QC procedure on the basis of a defined clinical quality requirement.
Lesson 10: Applications - How do you select QC acceptability criteria to satisfy CLIA QC guidelines? In Selecting QC procedures to satisfy CLIA requirements, a detailed step-by-step procedure is described that begins with the definition of quality according to the CLIA proficiency testing criteria for acceptable performance and uses OPSpecs charts for selecting controls rules and numbers of control measurements. Detailed applications are discussed by Dr. Neill Carey in Tips on Managing the Quality of Immunoassays.
Lesson 11: Applications - How do you determine the precision and accuracy needed for a test? In Quality by Design, Dr. Westgard discusses how to use an OPSpecs chart to establish precision and accuracy "specifications for purchase." In the application QC planning using European biologic goals, this approach is used to compare the maximum allowable CVs for cholesterol and glucose testing processes that are designed to assure the quality required by clinical, analytical, and biological quality requirements.
Lesson 12: Am I done with QC now? In Future Directions in Quality Control and in QC 2000, Dr. Westgard discusses the expected evolution of analytical quality systems and considers the needs of total automation as well as point-of-care applications. Finally, in Trends in Quality Management, Dr. Westgard discusses the broader developments in quality management practices and the continuing need for well planned and well managed laboratory testing processes. (Revised 11/99).
At various times during this course, it may occur to the overworked resident or consultant pathologist- 'Why?!'
The answer is not easy. On the one hand, QC is something that Quincy never seemed to be worried about, as he dashed about peering down microscopes, turning up results critical to the investigation in his lab, and so forth. On the other hand, we did learn in the first few months of our residency that Quincy had as little to do with the real world of the pathologist as Kermit has to do with the work of a marine biologist. Besides, how could Quincy be sure that his toxicology analyzers were giving reliable results?
Today, our role as pathologists, especially in community hospitals, demands that we take an active -- and, more important, educated -- part in planning and overseeing quality control in the laboratory, if we are to maintain the trust of our clients, the clinicians and their patients, and the certification of the regulatory bodies.
There will be numerous occasions when learning QC will seem overwhelming. The answer is to plough through the course, ignoring problems that seem insurmountable, and then return to them later when the larger picture looks clearer. It is advisable to work with a mentor who is knowledgeable in QC; but don't worry if you cannot find one. Your questions have usually been asked by someone else who has taken the course before you -- refer to the FAQs. If you still need help, Dr. Westgard will be glad to help you- email him at jo.westgard@hosp.wisc.edu. But remember- in order to minimize your time-benefit ratio- don't give up!
There is no syllabus at the moment for this course.
