SECTION E. DESIGN REVIEW

I. REQUIREMENTS

§ 820.30(e) Design review.

• Each manufacturer shall establish and maintain procedures to ensure that formal documented reviews of the design results are planned and conducted at appropriate stages of the device's design development.
• The procedures shall ensure that participants at each design review include representatives of all functions concerned with the design stage being reviewed and an individual(s) who does not have direct responsibility for the design stage being reviewed, as well as any specialists needed.
• The results of a design review, including identification of the design, the date, and the individual(s) performing the review, shall be documented in the design history file (the DHF).

Cross-reference to ISO 9001:1994 and ISO/DIS 13485 section 4.4.6 Design review.

II. DEFINITIONS

§ 820.3(h) Design review means a documented, comprehensive, systematic examination of a design to evaluate the adequacy of the design requirements, to evaluate the capability of the design to meet these requirements, and to identify problems.

III. DISCUSSION AND POINTS TO CONSIDER

In general, formal design reviews are intended to:

• provide a systematic assessment of design results, including the device design and the associated designs for production and support processes;
• provide feedback to designers on existing or emerging problems;
• assess project progress; and/or
• provide confirmation that the project is ready to move on to the next stage of development.

Many types of reviews occur during the course of developing a product. Reviews may have both an internal and external focus. The internal focus is on the feasibility of the design and the produceability of the design with respect to manufacturing and support capabilities. The external focus is on the user requirements; that is, the device design is viewed from the perspective of the user.

The nature of reviews changes as the design progresses. During the initial stages, issues related to design input requirements will predominate. Next, the main function of the reviews may be to evaluate or confirm the choice of solutions being offered by the design team. Then, issues such as the choice of materials and the methods of manufacture become more important. During the final stages, issues related to the verification, validation, and production may predominate.

The term "review" is commonly used by manufacturers to describe a variety of design assessment activities. Most, but not all, of these activities meet the definition of formal design reviews. The following exceptions may help to clarify the distinguishing characteristics of design reviews.

• Each design document which constitutes the formal output, or deliverable, of a design task is normally subject to evaluation activities, sometimes referred to as informal peer review, supervisory review, or technical assessment. These activities, while they may be called reviews, are often better described as verification activities, because they are not intended to be comprehensive, definitive, and multidisciplinary in their scope. Rather, their purpose is to confirm that design output meets design input. Verification activities affect and add to the design output, and are themselves subject to subsequent design review.
• Developers may conduct routine or ad hoc meetings to discuss an issue, coordinate activities, or assess development progress. Decisions from such meetings may not require formal documentation; however, if a significant issue is resolved, this should be documented. If the outcome results in change to an approved design document, then applicable change control procedures should be followed, as discussed in Section I (Design Changes).

Control of the design review process is achieved by developing and implementing a formal design review program consistent with quality system requirements. The following issues should be addressed and documented in the design and development plan(s).

NUMBER AND TYPE OF REVIEWS. It is a well-accepted fact that the cost to correct design errors increases as the design nears completion, and the flexibility to implement an optimal solution decreases. When an error is discovered at the end of the development cycle, difficult decisions have to be made regarding an acceptable corrective action. When that corrective action is implemented in haste, the result is often an unintended consequence leading to a new problem. Thus, formal design reviews should be planned to detect problems early. A corollary is that planners should presume that problems will be detected, and allocate a reasonable amount of time to implement corrective actions. Typically, formal reviews are conducted at the end of each phase and at important milestones in the design process.

As discussed in Section C (Design Input), it is beneficial in almost every case to conduct a formal review of the design input requirements early in the development process. The number of reviews depends upon the complexity of the device.

• For a simple design, or a minor upgrade to an existing product, it might be appropriate to conduct a single review at the conclusion of the design process.
• For a product involving multiple subsystems, an early design task is to allocate the design input requirements among the various subsystems. For example, in a microprocessor-based system, designers must decide which functions will be performed by hardware and which by software. In another case, tolerance buildup from several components may combine to create a clearance problem. System designers must establish tolerance specifications for each component to meet the overall dimensional specification. In cases like these, a formal design review is a prudent step to ensure that all such system-level requirements have been allocated satisfactorily prior to engaging in detailed design of each subsystem.
• For complex systems, additional reviews are often built into the development plan. For example, engineering sketches may be developed for prototyping purposes prior to development of production drawings. Evaluation of the prototype would typically culminate in a formal design review. Similarly, software development commonly includes a high-level design phase, during which requirements are elaborated to a greater level of detail and algorithms are developed to implement key functions. A formal design review would typically be conducted to review this work prior to beginning detailed coding.

There are a number of approaches to conducting formal design reviews at the end of the design process. In some organizations, engineering essentially completes the design, tests an engineering prototype, and conducts a formal design review prior to turning the design over to manufacturing. In such cases, an additional review will be needed after the design has been validated using production devices.

In some instances, components having long lead times may enter production prior to completion of the overall device design. The primary motivation for early production is to reduce time to market. The manufacturer runs the business risk that the design review at the end of the design process will uncover a defect that must be corrected in production devices before any devices are distributed.

All of these approaches to scheduling formal design reviews are valid. What is important is that the manufacturer establish a reasonable rationale for the number and type of reviews, based on sound judgment.

SELECTION OF REVIEWERS. In determining who should participate in a formal design review, planners should consider the qualifications of reviewers, the types of expertise required to make an adequate assessment, and the independence of the reviewers. Each of these concerns is discussed briefly in the following paragraphs.

Qualifications. Formal design reviews should be conducted by person(s) having technical competence and experience at least comparable to the developers. For a small manufacturer, this may require that an outside consultant be retained to participate in the evaluation of the design.

A manufacturer will often employ one or more specialists to conduct certain types of specialized assessments which are beyond the capabilities of the designers. For example, a mechanical engineer may be retained to perform a structural analysis of a design, and perhaps conduct vibration testing to verify its performance under stress. Such specialists may be assigned to participate in the formal design review. Alternatively, they may be assigned to make an independent assessment and submit observations and recommendations to the reviewers. Either approach is valid.

Types of expertise required. Many medical device designs involve a number of technologies, such as electronics, mechanics, software, materials science, or pneumatics. In addition, a variety of clinical and manufacturing issues may influence the design. Manufacturers should carefully consider which interests should be represented at formal design reviews. Subtle distinctions in reviewer perspective may have dramatic impact on device quality. For example, the marketing department of a small manufacturer shared a new design with several surgeons on their advisory board. The surgeons all thought the design was terrific. Subsequently, the manufacturer invited two experienced operating room nurses to participate in the final design review. During the course of the review, it became apparent that while surgeons may be the customers, nurses are the primary users of the device, and no one up to that point had consulted with any nurses. The nurses at the design review didn't like some of the features of the design. After some further market survey, the manufacturer decided to make changes to the design to accommodate these concerns. It was unfortunate (and expensive) in this case that the user requirements were not considered until late in the development cycle, but the design review was ultimately very successful.

Independence. The formal design review should include at least one individual who does not have direct responsibility for the design stage under review. In a small company, complete independence is very difficult to obtain. Within the context of formal design reviews, the practical solution is simply to ensure a fresh perspective, based on the principle that those who are too close to the design may overlook design errors. Thus, reviewers will often be from the same organization as the developers, but they should not have been significantly involved in the activities under review. As discussed in the following section, the formal design review procedures play a large role in assuring independent and objective reviews.

DESIGN REVIEW PROCEDURES. The manufacturer should have documented formal design review procedures addressing the following:

• Evaluation of the design (including identification of concerns, i.e., issues and potential problems with the design)
• Resolution of concerns
• Implementation of corrective actions

Evaluation of the design. Many formal design reviews take the form of a meeting. At this meeting, the designer(s) may make presentations to explain the design implementation, and persons responsible for verification activities may present their findings to the reviewers. Reviewers may ask for clarification or additional information on any topic, and add their concerns to any raised by the presenters. This portion of the review is focused on finding problems, not resolving them.

There are many approaches to conducting design review meetings. In simple cases, the technical assessor and reviewer may be the same person, often a project manager or engineering supervisor, and the review meeting is a simple affair in the manager's office. For more elaborate reviews, detailed written procedures are desirable to ensure that all pertinent topics are discussed, conclusions accurately recorded, and action items documented and tracked.

There is a dangerous tendency for design review meetings to become adversarial affairs. The reputation of the designers tends to be linked to the number of discrepancies found, causing the designers to become defensive, while the reviewers score points by finding weaknesses in the design. The resulting contest can be counterproductive. An added complication is the presence of invited guests, often clinicians, who are expected to provide the user perspective. These reviewers are often very reluctant to ask probing questions, especially if they sense that they may become involved in a conflict where all the rules and relationships are not evident.

These difficulties can be avoided by stating the goals and ground rules for conducting the formal design review clearly at the outset. While the designers are in the best position to explain the best features of the design, they are also most likely to be aware of the design's weaknesses. If the designers and reviewers are encouraged to work together to systematically explore problems and find solutions, the resultant design will be improved and all parties will benefit from the process. Participants must be encouraged to ask questions, avoid making assumptions, and think critically. The focus must be on the design, not the participants.

Not all formal design reviews involve meetings. For extremely simple designs or design changes, it may be appropriate to specify a procedure in which review materials are distributed or circulated among the reviewers for independent assessment and approval. However, such a procedure negates the benefits of synergy and teamwork, and should be considered only in cases where the design issues are limited in scope and well defined.

Resolution of concerns. The reviewers consider concerns raised during the evaluation portion of the formal design review and decide on an appropriate disposition for each one. There is wide variation in the way companies implement decision-making processes. In some cases, the reviewers play an advisory role to the engineering manager or other company official, who directs the formal design review and ultimately selects a course of action. In other cases, the reviewers are given limited or broad authority to make decisions and commit resources to resolve problems. The approach used should be documented.

In the real world, reviews often leave unresolved issues. Therefore, review procedures should include a process for resolving differences, and provide reviewers with enough leeway to make practical decisions while protecting the integrity of the process.

Implementation of corrective actions. Not all identified concerns result in corrective actions. The reviewers may decide that the issue is erroneous or immaterial. In most cases, however, resolution involves a design change, a requirements change, or a combination of the two. If the solution is evident, the reviewers may specify the appropriate corrective action; otherwise, an action item will be assigned to study the problem further. In any case, action items and corrective actions are normally tracked under the manufacturer's change control procedures.

RELATIONSHIP OF DESIGN REVIEW TO VERIFICATION AND VALIDATION. In practice, design review, verification, and validation overlap one another, and the relationship among them may be confusing. As a general rule, the sequence is: verification, review, validation, review.

In most cases, verification activities are completed prior to the design review, and the verification results are submitted to the reviewers along with the other design output to be reviewed. Alternatively, some verification activities may be treated as components of the design review, particularly if the verification activity is complex and requires multidisciplinary review.

Similarly, validation typically involves a variety of activities, including a determination that the appropriate verifications and reviews have been completed. Thus, at the conclusion of the validation effort, a review is usually warranted to assure that the validation is complete and adequate.