Design Controls

The concept of Design Controls is a mandatory system of procedures required for medical device manufacturers under the U.S. FDA's Quality System Regulation (QSR), specifically defined in 21 CFR Part 820, Subpart C (§ 820.30).

Design Controls are defined as a set of quality practices and procedures used to control the design process. Their fundamental purpose is to ensure that a medical device meets the user's needs, intended uses, and specified requirements.

1. Importance and Applicability

Definition and Goal

Design Controls ensure that the finished devices manufactured will be safe and effective and otherwise comply with the Federal Food, Drug, and Cosmetic Act (the act). By utilizing design controls, manufacturers can build quality, safety, effectiveness, and savings into their medical devices. Implementing adequate design controls is key to preventing future quality issues. Historically, about 44% of voluntary recalls from 1983 through 1989 might have been prevented by adequate design controls.

Applicability (When and To Whom)

Design controls are required for specific classes of devices:

• All Class II and Class III medical devices.
• Only certain Class I medical devices, specifically:
  • Devices automated with computer software.
  • Tracheobronchial suction catheters (868.6810).
  • Surgeon's gloves (878.4460).
  • Protective restraints (880.6760).
  • Manual radionuclide applicator system (892.5650).
  • Radionuclide teletherapy source (892.5740).
• Manufacturers should start applying design controls after the feasibility or "proof of concept" phase, and before the start of any Investigational Device Exemption (IDE).

2. The Nine Elements of Design Controls (21 CFR 820.30)

The Design Control requirement is broken down into nine essential, documented elements that guide the development process:

Element

Requirement (21 CFR 820.30)

Core Function/Objective

(b) Design and Development Planning

Establish and maintain plans that describe or reference design and development activities and define responsibility for implementation.

To organize the project, define interfaces (interactions between different groups or activities), and ensure the plan is updated as development proceeds.

(c) Design Input

Establish procedures to ensure design requirements are appropriate and address the device's intended use, user needs, and patient needs.

To define the physical and performance requirements (the basis for the design). Procedures must include a mechanism for addressing incomplete, ambiguous, or conflicting requirements. The outputs of risk management are essential inputs.

(d) Design Output

Procedures for defining and documenting design output in terms that allow adequate evaluation of conformance to design input requirements.

To specify the results of the design effort. Output must contain or reference acceptance criteria and identify outputs essential for proper functioning. The finished design output forms the basis for the Device Master Record (DMR).

(e) Design Review

Establish procedures to ensure formal documented reviews of the design results are planned and conducted at ** appropriate stages**.

To systematically examine the design, evaluate its adequacy, and identify problems. Review teams must include representatives of all concerned functions and an individual who does not have direct responsibility for the stage being reviewed.

(f) Design Verification

Procedures for verifying the device design to confirm that the design output meets the design input requirements.

"I made the product correctly". This is verification against internal specifications. Results must be documented in the Design History File (DHF).

(g) Design Validation

Procedures for validating the device design to ensure it conforms to defined user needs and intended use(s).

"I made the correct product". This must be performed under actual or simulated use conditions on initial production units, lots, or batches. It must include software validation and risk analysis, where appropriate.

(h) Design Transfer

Procedures to ensure that the device design is correctly translated into production specifications.

To move the proven design into manufacturing, ensuring it can be consistently produced.

(i) Design Changes

Procedures for the identification, documentation, validation or where appropriate verification, review, and approval of design changes before their implementation.

To control all alterations made to the design after initial establishment.

(j) Design History File (DHF)

Establish and maintain a DHF for each type of device.

To compile or reference the records necessary to demonstrate that the design was developed in accordance with the approved design plan and QSR requirements.

3. Integration with Risk Management and Quality Systems

Design Controls are fundamentally linked to risk management, reflecting FDA's focus on proactively ensuring safety and effectiveness.

Risk Analysis and Safety

• Mandatory Risk Integration: Design validation must include risk analysis, where appropriate. This is considered required unless a manufacturer can justify otherwise, and performing initial risk analysis earlier during design is advisable.
• ISO 14971 Integration: The ISO standard for medical device risk management (ISO 14971) requires that the outputs of risk management are explicitly used as one of the design and development inputs.
• Hierarchy of Risk Controls: When applying risk control measures, manufacturers are required to follow a hierarchy that favors safety inherent in the design:
  1. Inherently safe design and manufacture (e.g., selecting appropriate materials or designing to minimize sharp edges).
  2. Protective measures (e.g., safety guards, quality control checks).
  3. Information for safety (e.g., labeling, warnings, instructions for use, and user training). This last layer is considered the least effective as it relies heavily on user action and consistency.

Human Factors and Continuous Improvement

• Human Factors: Human factors (or usability engineering) is the study of the interactions between humans and the device interface, and it is a critical input to design control. The FDA provides guidance to manufacturers to help improve the design of devices to minimize potential use errors and resulting harm.
• Postmarket Role: Design Controls play a continual role in both premarket and postmarket device development. Problems identified via sources like complaints or nonconformities often trigger Corrective and Preventive Action (CAPA), which may result in necessary design changes that must, in turn, be controlled and verified/validated using the procedures established under Design Changes (820.30(i)). For example, certain specialized devices must document an appropriate end user device training program as part of their 21 CFR 820.30 design controls to mitigate the risk of incorrect operation.

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