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August 9, 2021
October 2021
· 10 min read
At NSF, we work with companies on root cause analysis training and help companies improve their investigation systems and reports. The CAPA hierarchy is one of the most simple yet most effective tools in our toolbox.
In this article, we will look at:
Have you ever reviewed an investigation report and wondered whether the proposed corrective and preventive action (CAPA) would be effective?
Sometimes, we shrug our shoulders and say, “At least they put something in place.” We all know that the FDA expects us to include an effectiveness check, but do we have enough guidance to make these checks meaningful?
NSF suggests that you consider these three questions:
Here are two examples of how you can make your effectiveness checks meaningful:
But are these requirements sufficient? Is there any way we can evaluate the CAPA before implementation? We will lose valuable time if we must wait three to six months for the answer. The regulatory risk increases as the clock keeps ticking.
We propose introducing a CAPA hierarchy that investigators can use to help them select an appropriate CAPA most likely to deliver the desired outcome. It can also be used by approvers. The CAPA hierarchy might even give investigators additional leverage to push back for a better solution or help them articulate weaknesses they saw in previous CAPAs. After all, some corrective actions ARE more effective than others.
Eliminate the possibility of error. This can be accomplished by eliminating the task. Here are some examples of how you can eliminate the possibility of errors:
Elimination can also be accomplished by a poka-yoke (an error-proof device). This concept is widespread in manufacturing, where a special fixture makes a part impossible to install incorrectly.
NSF participated in an investigation for IV bags that were shipped to the customer without a thermal print label. Every time the operator pushed the emergency stop button, the printer and camera would lose their memory. The printer did not know what to print, and the camera did not know what to reject. We eliminated the problem by revising the PLC program to automatically reject the in-process bags following an emergency stop. We also added a verification clause to the validation procedure.
Use your imagination to think of other ways to adopt poka-yoke to pharmaceutical production.
Change the current process by replacing it with a more reliable one. For example:
Make the process easier to perform so mistakes are less likely to occur. For example:
Improve detection by adding new or better sensors at the source, if possible. For example:
Understand that a corrective action that improves detection is inherently weaker than a corrective action that eliminates the problem. Why? Because detection does not prevent defects, it just prevents escapes. And defects cost you money!
Minimize the effect of the error. This is typically the weakest form of corrective action.
For most companies, product designs are constrained. Probably the only way to mitigate is to sort or rework, but this should be viewed as an interim step, not a permanent corrective action. This is true even if you design a perfect automated re-inspection system. Rework is a crutch.
Sometimes you can combine detection and mitigation. Here are some examples of what you can do:
Now that you are aware of the CAPA hierarchy, it is time to consider reviewing a sample of past CAPA actions. How many fall into the detection and mitigation categories (which are the least effective actions you can take)? The percentages will surprise you.
The CAPA hierarchy does not include retraining. Sometimes it isn't easy to identify the root cause. Just be careful not to fall into the “blame and train” trap when you can’t think of any alternative actions.
Training is necessary but not sufficient. What happens in six months when there is employee turnover? People are human, and people make mistakes. If training is one of the CAPA actions, be sure to supplement it with at least one additional CAPA that falls into the CAPA hierarchy categories listed in this article.
Roll out the CAPA hierarchy to your organization to implement better preventive actions that deliver significant improvements. With the CAPA hierarchy, you can anticipate an effective outcome rather than wait several months for the CAPA implementation only to be disappointed by the effectiveness check results.