The Eight Disciplines (8D) model is a problem-solving methodology used primarily within the automotive industry to identify root causes, correct them in the short term and prevent them in the long term.
Given its reputation for reliability in the automotive space, it's no surprise the method has been embraced by engineers in other industries tasked with solving similar types of problems. Drug and device manufacturing is one such space where 8D seems like a fit, particularly within corrective and preventive action (CAPA) programs.
But despite its success, the 8D model presents a serious compliance problem under both FDA and global ISO regulations—one that regulators are seizing on as evident by the top-cited inspectional observation within the device space since 2010: "Procedures for corrective and preventive action have not been [adequately] established" (21 CFR 820.100(a)).
In short, 8D's treatment of corrective action verification is at odds with FDA and ISO expectations. More specifically, 8D places corrective action verification ahead of implementation rather than after it. This puts the emphasis of verification on the implementation of corrective actions itself rather than the effectiveness of those actions—a serious procedural lapse.
Fortunately, mitigating the risk of importing 8D into a CAPA program is mainly a matter of understanding the problem. Here's a brief rundown of what 8D is and where the problem lies.
The 8D model was developed by the Ford Motor Company (then called "Team Oriented Problem Solving," or "TOPS") during the 1980s. The model proved so effective and easy to teach, it became Ford's primary method of documenting problem-solving efforts and is still widely used throughout the automotive industry today.
8D works by alternating inductive and deductive problem-solving steps to identify a root cause and work toward a resolution. This can be done a number of ways, but it typically includes using data-driven tools and analysis for inductive activities and an individual or group of subject matter experts to deduce results.
No matter how it's implemented, 8D follows a generally rigid set of eight core disciplines. These were codified in Grace L. Duffy's Modular Kaizen: Continuous and Breakthrough Improvement, published by the ASQ Quality Press:
D0: Plan—Plan for solving the problem and determine the prerequisites.
D1: Use a team—Establish a team of people with product/process knowledge.
D2: Define and describe the problem—Specify the problem by identifying in quantifiable terms the who, what, where, when, why, how, and how many (5W2H) for the problem.
D3: Develop interim containment plan; implement and verify interim actions—Define and implement containment actions to isolate the problem from any customer.
D4: Determine, identify, and verify root causes and escape points—Identify all applicable causes that could explain why the problem occurred. Also identify why the problem was not noticed at the time it occurred. All causes shall be verified or proved, not determined by fuzzy brainstorming. One can use 5 Whys and cause and effect diagrams to map causes against the effect or problem identified.
D5: Choose and verify permanent corrections (PCs) for problem/nonconformity—Through preproduction programs, quantitatively confirm that the selected correction will resolve the problem for the customer.
D6: Implement and validate corrective actions—Define and implement the best corrective actions.
D7: Take preventive measures—Modify the management systems, operation systems, practices, and procedures to prevent recurrence of this and all similar problems.
D8: Congratulate your team—Recognize the collective efforts of the team. The team needs to be formally thanked by the organization.
As mentioned earlier and shown above, 8D positions verification of corrective actions before implementation.
This is fundamentally at odds with both FDA and ISO regulations governing CAPA, which both require manufacturers to verify that the actions they took to correct a problem were actually effective at doing so. It's not enough to simply verify that they were implemented.
The relevant sections of both regulations are offered below.
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(3) Identifying the action(s) needed to correct and prevent recurrence of nonconforming product and other quality problems;
(4) Verifying or validating the corrective and preventive action to ensure that such action is effective and does not adversely affect the finished device;
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d) planning and documenting action needed and implementing such action, including, as appropriate, updating documentation;
e) verifying that the corrective action does not adversely affect the ability to meet applicable regulatory requirements or the safety and performance of the medical device;
f) reviewing the effectiveness of corrective action taken.
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As FDA Group consultant Brian Dense explains, medical device companies need to ensure their CAPA procedures verify effectiveness by analyzing data and that the process incorporates reasonable timeframes for collecting that data based on the products in question.
"Your verification of effectiveness has to come after you have implemented corrective actions. This is a general problem. Many procedures treat verification as going back to make sure actions were implemented. Really what it's asking for is verification that corrective actions were effective.
Every one of your effectiveness checks is going to be different. If you've got a high-volume manufacturing situation where you're making tens of thousands of devices each week, you may be able to do an effectiveness check a week later.
However, others might require months before they've gathered enough data to conduct an effectiveness check. The 8D process flips verification––but even without the 8D process, it's easy to misunderstand what the effectiveness check is. It's imperative that this is done after data is collected and analyzed."
The Ingredients of a Compliant CAPA Effectiveness Check
Simply verifying that all the actions you planned take were completed is not a valid CAPA effectiveness check. Instead, use the following components to guide the process:
Watch our free recorded webinar, The Complete Guide to Root Cause Analysis & CAPA, to learn more about compliant, effective problem-solving procedures and techniques for FDA-regulated manufacturers.