IVD Technology Magazine | IVDT Article Index
Originally published May, 1997
Commentary
Design control: IVD designers need to fine-tune their systems
Z. Frank TwardochlebFDA's new quality system regulation goes into effect on June 1, and with it will come a number of new regulatory requirements for the designers and manufacturers of IVDs. To harmonize U.S. practice with international standards, the regulation includes a number of new requirements based on ISO 9001, the fullest of the quality systems standards compiled by the International Organization for Standardization (ISO). These include new sections on management responsibility, purchasing controls, process validation, nonconforming products, preventive and corrective action, and servicing. But for IVD manufacturers, the most troublesome of the new requirements will undoubtedly be those related to design control (21 CFR 820.30).
FDA first brought the issue of design control to industry attention in 1989, when it published a guidance entitled "Preproduction Quality Assurance Planning: Recommendations for Medical Device Manufacturers." Since then, many IVD companies have implemented PPQA programs in various forms. Until now, however, these programs have not been open to FDA investigation.
With the advent of the design control requirements embodied in the new quality system regulation, major changes will occur in how IVD manufacturers do business. Starting June 1, manufacturers will be inspected for compliance with all the new quality system requirements, including those for design control. A year-long phase-in period will offer some leeway on compliance with the design control requirements, but FDA still expects that each manufacturer will have a design control system in place by this June 1, and that its system will be in full compliance with the regulation by June 1, 1998.
Despite industry calls for a sector-specific document that might help IVD manufacturers implement design controls, FDA has said that it has no plans to provide such guidance. But it has issued its "Final Design Control Inspection Strategy," a document intended to guide field inspectors and inform manufacturers about what a design control inspection should consist of. Available on the Center for Devices and Radiological Health web site (http://www.fda. gov/cdrh), the document is a key resource that IVD manufacturers should obtain and use in creating their design control systems.
It is encouraging to note that many IVD manufacturers already have some kind of design control system in place. For most of these companies, compliance with the new requirements will be less onerous than if they were starting with nothing. However, some of the existing programs were patterned after FDA's early PPQA guidance document, and now need to be fine-tuned in order to be brought into line with the final version of the requirements in the quality system regulation. Following are some key suggestions that an IVD manufacturer should consider when creating its design control system and the related design history file (DHF).
Distinguish Feasibility from Design. FDA has indicated that it does not expect manufacturers to maintain records of basic or exploratory research that is intended merely to confirm the feasibility of a product idea. Manufacturers should therefore seek to establish a bright line between studies that belong to the conceptual or feasibility phase of a product's development and material that relates to the actual design of the product and its related processes.
Keep It Simple. Written design control procedures should be as simple as possible. If they are complex, inevitably the entire design control program will be burdensome and time-consuming. This is especially true if the design team must constantly refer to the procedures to make sure they are being followed.
Make the System Auditor-Friendly. The manufacturer's design control system may be the subject of many types of inspection, including internal audits, notified body audits for ISO 9001 certification, and FDA inspection. A manufacturer can save itself a lot of headaches by creating a system in which such auditors can easily find their way. One way of doing this is to make use of the structure and language already contained in the ISO 9001 standard and FDA's quality system regulation. By labeling the system and its procedures with very clear and specific terms, such as design input and design output, auditors will easily be able to find the sections they need to review.
The same advice is true for the DHF. Dividing it into clear, recognizable sections, such as design review and design transfer, will simplify the auditor's task. Everything pertaining to the DHF should be placed in a single file.
Document Input and Output. A critical element of design control is the relationship between the gathering of input relevant to the product (e.g., regulatory requirements, voluntary standards, customer specifications) and the output embodied in the final product design. Manufacturers should therefore be certain that each of these aspects of the development process is thoroughly documented.
Each item of design input should be recorded clearly and include a reference to the source of the requirement (e.g., FDA, ISO, marketing department, user focus group). For each item of design input, the manufacturer should make certain that there is eventually a recorded design output. The final disposition of a design input may be to eliminate it--every requirement can't always be met--but it is still important to document how that decision is made, and to ensure that the design output records the final disposition.
Document Design Reviews. Manufacturers should be sure to document every major design review meeting as well as any minor meetings at which design-related discussions are held. Minutes of the major meetings should include three elements: a record of the discussion about each design input, whether there is a corresponding design output, and follow-up actions and activities to be covered during the next design review.
Consider Design Transfer. Another key contribution of design control is to eliminate the tendency of product engineers to design a product and then "throw it over the wall" to manufacturing. This practice is a sure recipe for confusion and for products that do not meet their specifications. Manufacturers should ensure that they have considered, during the design process, how their product is to be manufactured. Such considerations should embrace all of the processes necessary to complete the product, including lyophilization, sterilization, and packaging.
Design Changes. The iterative process of design control should make it easy to determine when all parts of a product's design are complete and ready for release to manufacturing. However, the status of subsequent changes may not be so clear. The manufacturer should ensure that its design control system clearly defines when design changes are to be placed under a formal change control system.
Maintain Document Confidentiality. Although the quality system regulation will give FDA inspectors access to a wide range of documents they were never before able to view, not all documents that might be requested need to be made available. For instance, information related to sales and marketing forecasts might be considered a vital component of the product development process. No doubt, some measure of design input depends on such data. Nevertheless, FDA investigators should not have access to them.
Similarly, notified bodies that audit companies for compliance with ISO 9001 sometimes require that postmarket surveillance data be maintained in the DHF as evidence that the design process was successful. However, FDA's quality system regulation does not require that such data be maintained in the DHF. Such documents are, of course, available to FDA inspectors elsewhere.
Take a Regulatory View. In the past, research and development engineers were responsible for writing most of the design documents that were not routinely subject to FDA inspection. Now, to ensure a successful inspection, nearly every document related to the design process will need to be written with a regulatory perspective in mind. Manufacturers should, therefore, ensure that all members of the design team are acquainted with the purpose of the documents they are creating, and they should submit each document to appropriate review prior to filing it in the DHF. Manufacturers should also take note that while FDA will be scrutinizing the DHF from a regulatory perspective, the file can also be used during civil litigation through the discovery process.
IVD manufacturers may well wish for more sector-specific guidance on the application of design control. No doubt, a document that described industry's current best practices in this area would be a boon to many. But with or without such guidance, FDA will soon begin inspecting the design processes related to new IVD designs and changes to existing designs to determine whether manufacturers are in compliance with the design control provisions of the quality system regulation.
By adhering to the suggestions provided above, IVD manufacturers will be able to avoid the worst pitfalls of an unsuitable design control program and to assemble a clear, concise, and straightforward DHF that can successfully pass an FDA inspection.
Z. Frank Twardochleb is president of Medical Device Auditing & Consulting, Inc. (North Potomac, MD).
