Corrective and Preventive Action (aka Capa corrective and preventive action) is the most widely misunderstood part of ISO 9001, and it’s the most powerful tool available to companies and industries of all types. The intent of this paper is to help people understand it as a tool, so that it is used to the fullest, and benefit from the business aspect of having a Quality Management System. This paper will therefore help you understand how to avoid harmful misunderstandings, and how to get the most business benefits from the CAPA process.
Common Misunderstandings
- It is common for people to mix Corrections with Corrective Actions.
- Corrections are actions you take to make a defective product good enough to be able to sell to a customer. The steps are detection (of a defective product- nonconformance) and disposition of the defective or non-conforming product. The point is that the manufacturer is focused only on the number of defective products on hand. Common methods for dispositioning are Scrap, Rework, Repair, Return to Vendor, use as is (with special approval from product specialists or customers).
Often Rework and repair requires additional process steps to remove the defect, and Best Practice is to document these steps for help in future incidents, and in calculating the Cost of Poor Quality.
It is a requirement to document incidents of nonconformance. These are called Records of Nonconformance. It is Best Practice to record all incidents of nonconformance, no matter how easy or simple or fast it is to dispose of the nonconforming product. The reason is that over time Nonconformances (NCs) provide valuable understanding of the manufacturing process.
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- Corrective Actions. The terms “Corrective Action” and “Preventive Actions” (CAPA) are special terms in Quality Assurance Technology to define actions that are taken to prevent Nonconformances in the future. The normal English usage of the term does not assume any time boundaries, and therefore some people mistakenly think that they have taken CAPA when they have performed actions such as rework, scrap, return to vendor, etc. These, of course, are Dispositions as described above.
To understand this special terminology- CAPA, we need to consider an axiom: “Product is the Result of a Process”. Just like a commonly known axiom: “A straight line is the shortest distance between two points”. It’s self-evident and does not need any proof.
Just remembering this axiom, it is easy to understand the magnitude of the difference between Corrections and CAPA. It is easy to understand that for doing CAPA, you must change the process that produced the NC. In other words, you work on the product to dispose of the NC, and you must work on the process to perform CAPA.
Also, you should note that CA generally PA is focused on negative triggers, such as nonconformances, findings, etc—aka Problems. There is difference, however, between Corrective Actions and Preventive Actions. Although they both prevent future problems, in the first case, the problems have already occurred. In the second case the problems are forecast to occur.
Another point to remember but usually considered are “Opportunities”, as the opposite of “Risk”. Mathematically speaking, the difference is only in the – or + sign. The work-flow are all the same--- because you are always focused on the process that needs to be changed to effectuate the risk or the opportunity. A good term for the process of enjoying an opportunity could be Opportunity Capture.
The above may be referred to as Capa corrective and preventive action.
- When you are in the realm of disposing of a Nonconforming Product, you are working on the product. For Capa Corrective Action, you must be working on the Process that produced the product. A good way to differentiate is to think about Health Care. When you have an illness, such as high-sugar condition, and trying to cure it—you are disposing of the illness—such as taking medication for high sugar. However, when you are changing your life style like reducing sugar intake, reduction of weight, doing regular exercise, you are trying to prevent the condition. If done right, and are successful , you may stop taking the medication. This is the capa meaning.
The Role of Risk Based Thinking (RBT) in CAPA.
Thinking about Risk in decision-making of all sorts is good way to determine the type of actions you need to be taking to continuously improve the Quality of your product and the effectiveness of all your work processes.
The decision to take Disposition Action for a Nonconforming product is easy. You MUST dispose of the NC product. Ignoring detected NCs is not a choice. Not doing so is the fastest path to a rapid downfall.
Whether or not you take Capa Corrective Action steps is a decision in which you have a choice. It should be based on your assessment of the risk of not taking CAPA action. The use of RBT in CAPA is an essential part of the system, and is called Risk Based Corrective Action, Do not fall into the trap of doing CAPA for all NCs. Many people do that. The result is a poor CAPA system, taking short-cuts, and diluting the power of a Good CAPA.
Most of all, you may end up spending more resources than is necessary.
RBT can solve this problem for you. The method is to do a proper Risk Assessment to determine if you should take the path of Process Improvement, or stick with current manufacturing processes with a review of Detection (i.e. Inspection) and Disposition methods. A popular metric for Risk Assessment is the Risk Priority Number (RPN), with an usual range of 1-1000. So, a RPN of say 950 is a no brainer—you must follow the CAPA workflow.
A RPN of say 74 is an indication that it’s a good business decision to freshen up the Inspection and Containment processes, and deal with the Cost of Poor Quality.
The best part of RBT is that it provides numerical values to assess if the CAPA undertaken was successful. The way to do that is to do another Risk Assessment at the end of the CAPA. So in the example above (950 RPN), you assess that the RPN has fallen to say 85 you have fact based assessment of the Effectiveness of the CAPA. This is special power of Risk Based Corrective Action.
The CAPA Work-Flow or the Capa Process
A comprehensive work-flow for a CAPA would consist of the following steps. This will ensure capa quality. The work-flow is the Capa Management Process.
- Identification of a candidate for CAPA. The candidates can be chosen from a multitude of sources, such as product nonconformances at all stages of manufacturing, process nonconformances, audit findings, customer complaints, Risk Assessments and others.
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- For most of these sources of candidates, it is a matter of escalation into the CAPA work flow. Examples: During the process of handling a NC, you would escalate to a CAPA. Similarly for Customer Complaints, HSE incidents, Audit findings, etc
- You should remember that the work-flow for CAPA and for Opportunity Capture is the same. Shifts in national economic activities, industry changes, keeping track of new technologies and markets are examples of sources of opportunities. Keeping an eye for opportunities provides a new set of candidates for the CAPA work-flow.
- Evaluating the Candidate. The evaluation of candidates is best done with Risk Assessment methodologies which simply stated keeps an eye the Magnitude of effect and the Probability of occurrence.
- In the case of negative impact candidates—which are by far the majority of candidates in a QMS, the term used for Magnitude is Severity, and the term for Probability is just Occurrence. Some people use another factor: Difficulty of Detection. The product of SXOXD- SOD is used. The most common method is called FMEA, and a common scale for each of the SOD is 1-10, thus giving an Risk Priority Number (RPN) ranging from 1 to 1000.
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- In the case of positive impact candidates the calculation would be even simpler—Just MXO.
Most people do not use a formal approach to decide whether to proceed with a candidate for CAPA. The advantages of using a formal approach is that records are kept, and in a computerized data-base system such as QISS there is big advantage of Search Capabilities that help with evaluating historical data.
Regardless of which method you use, there must be a recognition that each candidate must be approved or rejected after due consideration of resources and other factors. Also, remember that all candidates do not need to proceed further. It needs to be a deliberate decision.
- Containment of the Problem. This step is necessary to ensure that the problem doesn’t spread, moves forward, all the way to the end point—such as Final Inspection or the customer. Remember that this step is related to the process of Correction, and not a direct part of the Prevention process.
- Root Cause Analysis. This step is the strongest factor behind Capa Quality. Lets reiterate the QA axiom of Product is the Result of a process. So, to do a CAPA, we need to know which process or part of a process needs to be modified or replaced. To find that answer, we need to know what is or would be the cause, and work on that. In the vast majority of cases, the intent would be to eliminate the root cause.
It should be noted that although the common term is Root Cause, the pursuit of a comprehensive one cause will likely show that there are several that can be classified as Direct, Contributing, and Root. To do a more effective CAPA, all of the different causes in the network should be considered examined.
- Solution Generation. This is a typical manufacturing engineering activity that yields a new process to modify the ineffective one or replace it with a new one. It should follow similar rigor and documentation.
- Solution Implementation. This again is a typical manufacturing engineering activity to ensure that the new process is implemented as designed.
- Check for Effectiveness. This is the second most important step for Capa Quality. This should be done to ensure that the CAPA was effective in preventing future occurrences of the problem that was identified. The following methods are recommended:
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- Reassessment of the Risk Level (RPN). The CAPA should reduce the risk to the desired level.
- Running the new process to verify that the problem does not occur over an appropriate period of time.
- Do tests to verify that there is reason to believe that the probability of occurrence is low enough
- Re-Evaluation: When appropriate, you might want to schedule a Re-Check of the effectiveness after a period of time.
- Ensure that related documents are updated. This is to ensure that new procedures are developed and existing ones updated as appropriate. Also that affected personnel are trained.
- Design and implement appropriate reports and analytics. This is the third most important factor for Capa Quality. There should be a number of reports and analytics designed and implemented to monitor the health of the CAPA process also known as (Capa Plan) as appropriate.
The following flow chart helps understand the flow, and interactions between the steps of the capa management process.
