Understanding how to prevent mistakes in manufacturing starts with learning why errors are made in the first place.

Human Error and Quality Control in Medical Devices

Human error is a broad category that includes the clearly identifiable, easily diagnosable, and seemingly excusable mistakes we all make. Error encompasses all those occasions in which a planned sequence of mental or physical activities fails to achieve its intended outcome, and when these failures cannot be attributed to the intervention of some chance agency. The definition of error may be complex but the outcome in the workplace, where accuracy is paramount, is not.

ProdDevIns_sherman.jpgHuman errors are often simple mistakes that can be catastrophic to those responsible, and more importantly, to the user or patient. Avoiding mistakes is an important consideration for companies striving to reduce errors.

Error reduction was addressed more than 30 years ago by W. Edwards Deming, a quality expert. He cited the need to seek a fresh approach to reduce mistakes and defective workmanship.1 Deming noted, that in many organizations, human error accounts for more than half of unnecessary business expenses. Of that portion, the rule of thumb is that about 85% result from automatic errors of execution, the causes of which remain inadequately understood and addressed.2 One of Deming’s quotations is worth repeating: “Defects are not free. Somebody makes them and gets paid for making them.”

There are a number of articles and several recent books that deal with human errors, how they occur, and what to do about them. Many such resources can be used for training purposes. This article will discuss why we make mistakes, the concept of poka yoke (mistake proofing), and various means to reduce mistakes, including training methods, checklists, and flow charts. The article will also provide suggestions for procedures designed to address a major cause of recalls or other corrective action. 

Why We Make Mistakes

One reason for making mistakes involves the power of first impressions. Most people stay with an initial choice for an answer to a test question at least 70% of the time, even when they learn that the answer is incorrect. Nearly 80 years of research on answer changing shows that most people who change their answers usually improve their test scores.3 Moreover, most people let their minds wander more often than they might think. According to one study, students reported that their minds wandered an average of 5.4 times in a 45-minute session. Depending on the experiment, people tend to spend up to half their time working on a task thinking about other things, even when they have been explicitly told to pay attention.4 Another reason is that most of us are not equipped for multitasking. The number of things we can do at once is extremely limited. In general, the human memory cannot retain more than five unrelated items at one time; many of us retain even less.  Multitasking is not thinking—it impairs the ability to think. Thinking means concentrating on one thing long enough to develop an idea about it.5 Individuals do their best thinking by slowing down and concentrating. Furthermore, individuals often blame the wrong cause, and thus learn little from a mistake experience.

To develop a quality error reduction program it is critical to understand what constitutes errors of thinking. Some researchers categorize five different types of erroneous thinking, as follows:5

  • Partialism. This occurs when the thinker observes problems through one perspective only.

  • Adversary. This occurs when the thinker believes that because someone else is wrong, he should be right (e.g., some politicians use this to sway voters).

  • Time Scale. This happens when the thinker sees a problem from a limited time frame.

  • Initial Judgment. This occurs whenever the issue or problem is not considered objectively.

  • Arrogance and Conceit. This occurs whenever the thinker believes that his or her solution is absolute and no better one exists.


All of this information should be considered in the company’s training program and accompanied by lessons learned from 483s and other warning letters.

Other reasons for making mistakes in the workplace are similar to those made by healthcare practitioners who use medical devices. The errors are described in an FDA guidance document for human factor engineering.6 Like healthcare personnel, individuals working for medical device companies vary greatly in their physical, sensory, and mental abilities. The latter refers to higher mental phenomena such as memory, information processing, use of rules and strategies, hypothesis formation, and problem solving. An employee’s performance can be compromised by noise, poor lighting, glare-producing surfaces, excessive heat, improperly used cleaning products, electrical interference, poorly written procedures, inadequate training, a wide array of equipment used, stress, and fatigue. Risk influencing factors (RIFs) worsen natural tendencies to make errors.

Poka Yoke and Six Sigma in Device Manufacturing

Quality personnel focusing on defect prevention can use principles embodied in mistake proofing or poka yoke. The system involves the use of any automatic device or method that either makes it impossible for an error to occur or makes the error immediately obvious once it has occurred.7 Unfortunately, poka yoke is not implemented by medical device companies as often as it should be. Neither ISO 13485:2003 nor the quality system regulation (QSR) under corrective and preventive action reference problem solving or error proofing. These topics are, however, included in ISO 16949:2009, the quality management standard that contains particular requirements for the application of ISO 9001:2008 for automotive production and relevant service organizations. The standard suggests that organizations incorporate error-proofing methods into corrective action policies and implement a defined process for problem solving designed to identify and eliminate root causes. No guidance is given for implementation, however. The recently issued final document on corrective and preventive action and related QMS processes from the Global Harmonization Task Force does not directly refer to problem solving or error proofing techniques, however, it does describe a number of statistical and nonstatistical techniques to be used for analysis.8

The training section of the QSR states that personnel should be made aware of device defects that may occur from improper performance of their specific jobs. Personnel who perform verification or validation activities must be made aware of defects or errors that may be encountered as part of their job function.9

Such notification requirements are admirable. But without addressing error proofing, they are insufficient. The Six Sigma problem solving approach known as DMAIC is a road map that can be followed for all projects and process improvements.10 It includes the following steps:

  • D—Define the overall problem.

  • M—Measure the problem to gather accurate and sufficient measurements and data.

  • A—Analyze the data to see if they are consistent with the problem definition and use these data to identify a root cause.

  • I—Improve processes. Once a solution is identified, it must be implemented and the results must be verified with independent data.

  • C—Control the solution. A verification of control must be implemented. A robust solution will be easier to keep in control than a qualitative one.

Education and Training

Only a few well-established programs that deal with aspects of thinking have taken hold in universities. Critical and creative thinking, reflective and metacognitive thinking (awareness and understanding one’s own thought processes), self-regulation, decision-making, problem solving, and other disciplinary forms of thinking are taught and practiced. Such programs should also be part of career development initiatives and offered to all employees. Problem solving and good quality thinking are essential skills for employees to attain, now more than ever.

Training should be industry specific. Employees should be encouraged to pay attention to detail, avoid behavior that results in unwanted outcomes, and focus on past experiences of dealing with past problems. Once employees become aware of the basic principles they are often able to apply experience of their own work to find practical ways of reducing the risk of error. Recognition that adverse influences (rather than individual shortcomings) are the intent of training reassures employees that the company is concerned with finding constructive ways to avoid error rather than blaming people.2 Training programs could begin with this oft-cited quotation by Voltaire, the noted French philosopher: “No problem can withstand the assault of sustained thinking.”

Checklists

One of the means to minimize errors is to use a checklist, otherwise known as work procedures or conformation check sheets.7 Checklists are now being aggressively promoted in medical literature and the popular press, and rightly so.11–13
Many hospitals have started to implement more comprehensive checklist procedures in the operating room aimed at increasing compliance with practices known to reduce complications and enhance teamwork. WHO has reported that such checklists cut surgical morbidity and mortality almost in half.14 A recent controlled study, showed that the implementation of a comprehensive checklist in six regional and tertiary care centers in the Netherlands improved outcomes substantially. The study also provided insights into why checklists work and should be considered by manufacturers of medical devices.15
Quality teams should review each of their processes and reported errors to determine whether a checklist would prove beneficial. When creating a checklist for steps in a process, it is a good idea to first prepare a flow chart to determine what the steps are and how they should be sequenced.

Flow Charts

Flow charts are diagrams that use graphic symbols to depict the nature and flow of steps in a process. They have a number of benefits:

  • They promote the understanding of the process.

  • They provide a tool for training.

  • They can identify problem areas and opportunities for improvement.

  • They depict customer-supplier relationships.


Flow charts are similar in style to cause-and-effect diagrams, which are defined as graphic tools that help identify, sort, and display possible causes of a problem or quality characteristic. A cause-and-effect diagram uses an orderly, easy-to-read format and helps to determine root causes, encourages group participation, indicates possible causes of variation, and most importantly, increases knowledge of the process.

A Procedure for Mistake Proofing. A mistake proofing procedure should be developed to include a flow chart of the process when possible. Each step of a particular process should be reviewed to determine where or when human errors are likely to occur. The procedure should require working back through the process to find the source of each potential error. It may be possible to eliminate an error by omitting the step that causes it or by replacing that step with one that is error-proof. The procedure should also include methods of detecting errors that are impossible to prevent and specify ways to minimize their effects, including inspection levels and techniques. This could include successive inspections of self and source. The procedure should be discussed at each training program to ascertain how it can be used more effectively. The book Quality Toolbox 2nd Edition provides an excellent section on mistake proofing that can be used to write the procedure and to understand inspection methods. It also includes a sample flow chart.10

Conclusion

It is common knowledge that errors committed by employees can be extremely costly from both a regulatory and litigious perspective and can cause irreparable damage to a company’s image. More importantly, these errors can cause injuries to patients or users of devices. It is astonishing that companies spend so little time training employees to think about thinking and to adopt mistake-proofing and problem-solving methods. This is especially perplexing in light of the techniques that are readily available to management. Six Sigma and poka yoke programs are two examples that companies can use to reduce costs and improve quality. Such programs can also be used to train employees on mistake proof methods and awareness.

References

1.    WE Deming, Out of the Crisis (Cambridge, MA: MIT Press, 1986).
2.    JM Evans, “Look for Trouble,” Quality Progress  39, no. 12 (December 2006): 56–62.
3.    H Treason, Human Error (Cambridge, UK: Cambridge Univ Press, 1990).
4.    C Zimmer, “The Brain; Stop Paying Attention: Zoning Out is a Crucial Mindset,” Discover Magazine, (July/Aug 2009): 24–25.
5.    A Raghunathan, “How to Improve Your Thinking,” Psychology4All.com; available from Internet: www.psychology4all.com/Thinking.htm.
6.    “Do It By Design” FDA; available from Internet: www.fda.gov/downloads/MedicalDevices/DeviceRegulationandGuidance/GuidanceDocuments/UCM095061.pdf.
7.    NR Tague, Quality Tool Box 2nd Ed., (Milwaukee, WI: ASQ Quality Press, 2005).
8.    “Quality Management System-Medical Devices-Guidance on Corrective Action and Preventive Action and Related Processes,” Global Harmonization Task Force Final Document, Study Group 3, November 2010.
9.    21 CFR Part 820.25 (b)(1) and (b)(2).
10.    W Brussee, Statistics for Six Sigma Made Easy (New York, NY: McGraw-Hill, 2004).
11.    R Ritchhart, DN Perkins, “Learning to Think: the Challenges of Teaching Thinking” in The Cambridge Handbook of Thinking and Reasoning, ed. KJ Holyoak and RG Morrison, (New York: Cambridge University Press, 2005).
12.    P Pronovost et al., “An Intervention to Decrease Catheter-Related Bloodstream Infections in the ICU,” New England Journal of Medicine 355 (2006):2725–2732.
13.    P Pronovost  and E Vohr, Safe Patients, Smart Hospitals: How One Doctor’s Checklist Can Help Us Change Healthcare from the Inside Out (New York, Hudson Street Press, 2010).
14.    A Gawande, The Checklist Manifesto: How to Get Things Right (New York: Metropolitan Books, 2010).
15.    AB Haynes et al., “A Surgical Safety Checklist to Reduce Morbidity and Mortality in a Global Population,” New England Journal of Medicine 360 (2009):491–499.

Further Reading

Problem-solving techniques are readily accessible. One of the first systematic methods was put forward by in Charles Kepner and Benjamin Tregoe in their work, called the New Rational Manager. In addition, a recent book by Greg Fainberg, called How to Solve Just About any Problem: Timeless Practices for Solving Problems provides comprehensive practical information useful in solving problems. It includes guidance, insights, checklists, and templates. He believes that teaching people to think effectively, solve problems, and make better decisions are the most important enterprises in the world today. Medical device companies that haven’t already done so should adopt his philosophies and suggestions as part of their training programs.

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