An integral part of developing medical devices is investigating issues that arise with the manufacturing process or with the device’s function or safety. Root cause analysis is an approach used to identify the underlying cause of the issue.
The goal of the approach is to prevent the problem from reoccurring by eliminating its source. It can also be an excellent opportunity for teams to gain insights into their processes and help prevent future problems.
When issues arise with a medical device, a root cause analysis offers an opportunity to gain understanding that will help with the current problem and provide insight moving forward. In addition, 21 CFR 820:100 states that manufacturers must have established procedures for implementing corrective and preventive action (CAPA), and these procedures must include “investigating the cause of non conformities relating to product, processes and the quality system.” Root cause analysis fills this role.
Not all investigations will be the result of a CAPA issue, some may arise from nonconformance, complaints, audits, and other avenues. Conducting root cause analysis, regardless of the reason for the investigation, can help improve quality and prevent problems in the future.
The process of investigating a problem involves several steps, with root cause analysis being only one part of the process. Once the problem is identified, its scope understood, and proper notifications are made, then a root cause analysis should be implemented. Once the analysis is complete, the results must be used to create a plan to correct the problem and prevent it from recurring or becoming systemic.
Root cause analysis is not defined by the tools used, but by the goal of identifying the underlying cause of the issue. However, there are several tools that have been used successfully in root cause analysis and quality teams should be familiar with them. They may include:
The tool or tools that will best reveal the root cause may vary with circumstances, as not all of these tools will necessarily be used in a root cause analysis. It may be appropriate to use other tools for the analysis as well.
One of the more commonly used tools for root cause analysis is 5 Whys. The concept is simple: start with asking why an issue occurred, and then when an answer has been settled upon, ask why that happened. Continue narrowing down the cause with “why” questions about the previous question’s answer.
In the end there may be more or less than five whys, but the point is to get to the true root cause rather than settling on a superficial answer.
A Fishbone Diagram, also called a cause and effect or Ishakawa diagram, is a visual root cause analysis tool that helps sort potential causes into categories. It starts with a problem statement, placed at the position of the fish’s mouth, with the backbone extending from it. Major categories that may have contributed to the problem are placed in the position of “bones” branching off from the backbone. The categories can be further broken down with subcategories arising from each branch.
The Fishbone diagram is an especially effective tool to use in a group setting, and helps prompt the team to consider all the possible causes rather than focusing on the first plausible scenario. It works particularly well when combined with the “5 Whys” approach to reach the root cause.
Investigations into quality issues require thorough documentation so they can be reviewed during an audit. This documentation must include the root cause analysis and any resulting corrective action plan.
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