2019 FDA Guidance - Off-The-Shelf Software Use in Medical Devices

OBSOLETE: Replaced by the 2023 Guidance 🔗

About this Transcript 🔗

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Preamble 🔗

Document issued on September 27, 2019. For questions about this document, contact the Division of Digital Health by e-mail at digitalhealth@fda.hhs.gov.

I. Introduction 🔗

Off-the-shelf (OTS) Software is commonly being considered for incorporation into medical devices as the use of general-purpose computer hardware becomes more prevalent. The use of OTS Software in a medical device allows the manufacturer to concentrate on the application software needed to run device-specific functions. However, OTS Software intended for general-purpose computing may not be appropriate for a given specific use in a medical device. The medical device manufacturer using OTS Software generally gives up software life cycle control, but still bears the responsibility for the continued safe and effective performance of the medical device. This guidance document was developed to address the many questions asked by medical device manufacturers regarding what they need to provide in a premarket submission to the FDA when they use OTS Software. The specific response to these questions depends on the medical device in question and the impact on patient, operator, or bystander safety if the OTS Software fails. Thus, the answer to the question, “What do I need to document?” may differ and is based on the risk analysis that is an integral part of designing a medical device. The detail of documentation to be provided to FDA and the level of life cycle control necessary for the medical device manufacturer increase as severity of the hazards to patients, operators, or bystanders from OTS Software failure increases. This document lays out in broad terms how the medical device manufacturer can consider what is necessary to document for submission to the Agency. A basic set of need-to document items is recommended for all OTS Software, and a detailed discussion is provided on additional (special) needs and responsibilities of the manufacturer when the severity of the hazards from OTS Software failure become more significant. For the current edition of the FDA-recognized standard(s) referenced in this document, see the FDA Recognized Consensus Standards Database. 1 For more information regarding use of consensus standards in regulatory submissions, please refer to the FDA guidance titled Appropriate Use of Voluntary Consensus Standards in Premarket Submissions for Medical Devices. 2 ” FDA's guidance documents, including this guidance, do not establish legally enforceable responsibilities. Instead, guidances describe the Agency’s current thinking on a topic and should be viewed only as recommendations, unless specific regulatory or statutory requirements are cited. The use of the word should in Agency guidance means that something is suggested or recommended, but not required.

II. Scope 🔗

The purpose of this document is to describe the information that generally should be provided in a medical device application involving OTS Software. This information is in addition to the documentation described in the Guidance for the Content of Premarket Submissions for Software Contained in Medical Devices. 3 Many of the principles outlined herein may also be helpful to device manufacturers in establishing design controls and validation plans for use of OTS Software in their devices. This guidance discusses key elements reviewers should look for in the submission, thereby providing a common baseline from which both manufacturers and reviewers can operate. This should improve predictability of Agency interaction with sponsors regarding applications involving OTS Software. The guidance provided in this document reflects a safety-based approach to risk management and is designed to be consistent with international standards on risk management. Existing international standards indicate that the estimation of risk should be considered as the product of the severity of harm and the probability of occurrence of harm. Probabilities of occurrence are calculated based on clinical and engineering considerations. On the clinical side, manufacturers use patient populations, user skill sets, labeling, and risk benefit analysis to calculate risk and acceptable risk levels. On the software engineering side, probabilities of occurrence would normally be based on software failure rates. However, software failures are systematic in nature and therefore their probability of occurrence can not be determined using traditional statistical methods. Because the risk estimates for hazards related to software cannot easily be estimated based on software failure rates, CDRH has concluded that engineering risk management for medical device software should focus on the severity of the harm that could result from the software failure. ‘Hazard Analysis’ is defined as the identification of hazards and their initiating causes. Based on the definition of ‘Risk Analysis, 4 ’ hazard analysis is actually a subset of risk analysis; because risk analysis for software cannot be based on probability of occurrence, the actual function of risk analysis for software can then be reduced to a hazard analysis function. Technically speaking, the use of either term risk or hazard analysis is appropriate. However, CDRH has chosen to use the term hazard analysis to reinforce the concept that calculating risk based on software failure rates is generally not justified, and that it is more appropriate to manage software safety risk based on the severity of harm rather then the software failure rates.

III. Definitions 🔗

  1. Is life threatening,
  2. Results in permanent impairment of a body function or permanent damage to a body structure, or
  3. Necessitates medical or surgical intervention to preclude permanent impairment of a body function or permanent damage to a body structure.

Permanent – For the purpose of this subpart, permanent means irreversible impairment or damage to a body structure or function excluding trivial impairment or damage.

Other software terminology used in this document is defined in FDA's Glossary of Computer System Software Development Terminology. 7

IV. OTS Software Decision Schematic 🔗

The content of the application supporting use of OTS Software in a medical device depends on the results of the hazard analysis. Figure 1 provides a schematic of the decision process and a table of contents for Section V of this guidance document.

Table 1 summarizes the recommended contents for an OTS Software submission based on Figure 1.

Table 1. Documentation Summary from Figure 1.

Minor Level of Concern **before mitigations** Minor Level of Concern **after mitigations** Moderate Level of Concern Major Level of Concern **after mitigations**
Hazard Analysis Hazard Analysis Hazard Analysis Hazard Analysis
Basic Documentation Basic Documentation Basic Documentation Basic Documentation
Hazard Mitigations Hazard Mitigations Hazard Mitigations
Describe and Justify Residual Risk Describe and Justify Residual Risk
Special Documentation

V. OTS Software Use 🔗

A. Basic Documentation for OTS Software 🔗

The OTS Software Basic Documentation is intended to answer the following questions:

  1. What is it? For each component of OTS Software used, the following should be specified:

Note: The medical device manufacturer should only use the OTS Software as specified in an appropriate document, i.e., design record. If the version of the OTS Software changes, the appropriate document should be updated to reflect the change.

Note 1: FDA recommends that software test, verification, and validation plans identify the exact OTS Software (title and version) that is to be used. When the software is tested it should be integrated and tested using the specific OTS Software that will be delivered to the user.

Note 2: If the manufacturer allows the use of the medical device with different versions of OTS Software, then the manufacturer should validate the medical device for each OTS Software version.

B. OTS Software Hazard Analysis 🔗

A comprehensive risk management approach includes hazard analysis and mitigation that continues iteratively throughout the life of the product. The manufacturer is expected to perform an OTS Software hazard analysis as a part of a medical device (system) hazard analysis.

OTS Software failure, malfunction, or misuse may present a hazard to the patient, operators, or bystanders. Figure 2 summarizes the typical hazard management and mitigation process that would include a hazard analysis of the OTS Software component.

The submission should include the following information to document the OTS Software hazard analysis:

Note: A tabular format of the OTS Software hazard analysis or a tabular summary will facilitate review. The hazard analysis for OTS Software may be included in the overall device hazard analysis provided adequate documentation is provided.

If the device with the OTS Software represents a Minor Level of Concern, then the Level of Concern for the OTS Software can be no greater. The hazard analysis for the OTS Software in such a device may simply document the Minor Level of Concern of the device.

Where failure, malfunction, or misuse of the OTS Software poses no possibility of injury to the patient, operators, or bystanders, then the OTS Software is said to present a Minor Level of Concern, and the fulfillment of the Basic Documentation (see Section V.A) will be considered sufficient.

C. OTS Software Hazard Mitigation 🔗

Hazard mitigation activities may seek to reduce the severity of the hazard, the likelihood of the occurrence, or both. Hazard mitigation interventions may be considered in three categories with the following order of precedence:

Figure 2. Typical Hazard Analysis and Mitigation

These approaches may involve hardware and/or software. These three mitigation approaches are by no means mutually exclusive and may be used concurrently. The most desirable approach is to design in effective controls, i.e., eliminate the need for a hazardous operation or component. Protective measures are considered passive (from the user’s standpoint) since they do not require any action on the part of the user. The least effective approaches depend on some action (or lack of action) on the part of the medical device user.

The submission should include the following information to document the OTS Software hazard mitigation:

  1. A list of all identified medical device hazards associated with the OTS Software;
  2. The steps taken to mitigate each hazard; and
  3. The residual risk.

Note: A tabular format of the risk management or a tabular summary will facilitate review. These results will typically be included as a part of the overall medical device hazard analysis and mitigation plan.

One example of a comprehensive approach to injury prevention in public health was developed around ten “countermeasures. 9 ” Table 2 (see next page) illustrates a generic approach to the hazard mitigation, in this case, to preventing injury-related energy release to patients, operators, or bystanders.

With implementation of each hazard mitigation, the residual risk is assessed as well as assessment of any new hazards that may be introduced.

Acceptable levels of residual risk, based on the severity or the likelihood of the residual risk occurring, will depend on the intended use of the medical device and the function performed by the software. In the case of diagnostic tests, injury includes results that can lead to unnecessary invasive diagnostic testing (e.g., biopsy) or withholding or delaying important diagnostic or therapeutic procedures.

The sponsor will need to describe and justify the residual risk (Section V.D) for Moderate or Major Levels of Concern. Where failure, malfunction, or misuse of the OTS Software is likely to result in death or serious injury to the patient, operators, or bystanders, then the OTS Software is said to present a Major Level of Concern. If the residual risk from the OTS Software presents a Major Level of Concern, the sponsor will need to fulfill Special Documentation (Section V.E).

Table 2. Injury Reduction Countermeasures

Countermeasure
1. Prevent accumulation of the energy.
2. Reduce the amount of the energy delivered.
3. Prevent inappropriate release of the energy.
4. Modify the release of the energy.
5. Separate the patient from the energy in time and space.
6. Provide physical barriers between the energy and the patient.
7. Change the surfaces or basic structures at the interface.
8. Reduce likelihood of misapplication or Increase resistance of the patient.
9. Provide rapid emergency response to injury.
10. Improve medical care and rehabilitation after the injury.

D. Describe and Justify Residual Risk 🔗

The sponsor should provide a detailed (complete) discussion of the risk that remains.

The risk related to the use of OTS Software should be considered in relation to the risk of the alternatives, e.g., custom developed software. Any experience (data) with the use of the OTS Software in this or a related application should be presented by the sponsor and will be considered by the reviewers. Whether the residual risk is acceptable depends on the specific medical device application.

E. Special Documentation for OTS Software 🔗

To fulfill Special Documentation for OTS Software of a Major Level of Concern, the medical device manufacturer is expected to:

  1. Provide assurance to FDA that the product development methodologies used by the OTS Software developer are appropriate and sufficient for the intended use of the OTS Software within the specific medical device. FDA recommends this include an audit of the OTS Software developer’s design and development methodologies used in the construction of the OTS Software. This audit should thoroughly assess the development and qualification documentation generated for the OTS Software (see Note below). Note: If such an audit is not possible and after hazard mitigation, the OTS Software still represents a Major Level of Concern, the use of such OTS Software may not be appropriate for the intended medical device application.
  2. Demonstrate that the procedures and results of the verification and validation activities performed for the OTS Software are appropriate and sufficient for the safety and effectiveness requirements of the medical device. Verification and validation activities include not only those performed by the OTS Software developer, but also include those performed by the medical device manufacturer when qualifying the OTS Software for its use in the specific medical device.
  3. Demonstrate the existence of appropriate mechanisms for assuring the continued maintenance and support of the OTS Software should the original OTS Software developer terminate their support.

VI. OTS Software Used in Marketing Applications 🔗

A. Examples 🔗

Examples of medical devices using OTS Software are described in this section. These examples illustrate the reasoning that leads to defining the Level of Concern for a medical device and thus the kinds of development processes that should be used and the information to be provided in a regulatory submission.

(1) Corneal Topographer 🔗

Minor Level of Concern medical device (see Section V.A).

Intended Use: A corneal topographer provides images of the abnormalities in the curvature of the cornea, the simplest being astigmatism.

Description: A corneal topographer consists of a hollow cone that the patient looks into from the base looking towards the interior of the point (like looking into the big end of a megaphone with one eye). The inside of the cone is white with black concentric circles. The concentric circles reflect off the eye and are imaged by a camera with a computer controlled lens situated at the point of the cone looking at the patient’s eye. The shapes of the reflections of the concentric circles are used to develop a topographic map of the cornea curvature that is printed out.

OTS Software: An OTS operating system such as Windows is commonly used to interface the user, the microcomputer hardware platform, the corneal topographer, data storage, and output devices.

OTS Software Level of Concern: A corneal topographer represents no threat of direct harm to the patient. The risk of indirect harm from a misdiagnosis relating to medical device malfunction is small since the worst case is an incorrect image that is considered correct. The OTS Software in this medical device thus represents a Minor Level of Concern (see Section V.B) and should satisfy Basic Documentation (see Section V.A).

(2) Perineometer 🔗

Minor Level of Concern medical device (see Section V.A).

Intended Use: Perineometers are used to provide feedback to a patient performing muscle strengthening exercises (Kegel exercises) for the treatment of certain types of urinary incontinence.

Description: There are two types of perineometers: those that measure pressure, and those that measure electrical activity (EMG) from muscles. Each device consists of a probe that is placed into either the vagina or the rectum, and a monitoring unit. The pressure devices use an air-filled probe connected to the monitoring unit by a piece of plastic tubing. When the patient performs the exercise, the probe is compressed, and the monitoring unit reports the change in pressure. The electrical devices use an electrode to measure the electrical activity of the target muscles during the exercises, and this information is reported by the monitoring unit.

OTS Software: An OTS operating system, such as DOS or Windows, may be used to record and display the data collected by the monitoring unit.

OTS Software Level of Concern: Perineometers represent no threat of direct injury to the patient, since no energy is applied by the medical device to the patient. The risk of indirect injury due to inaccurate feedback during the exercise session is expected to be small, as these medical devices are only used as an adjunct to exercise therapy, and they are used under clinical supervision. The OTS Software in this medical device thus represents a Minor Level of Concern (see Section V.B) and should satisfy the Basic Documentation (see Section V.A).

(3) Implantable Medical Device Programmers 🔗

Describe and Justify Residual Risk (see Section V.E).

Intended Use: An implantable medical device programmer provides interface and two-way communication with an implantable cardioverter-defibrillator (ICD) or cardiac pacemaker.

Description: An implantable medical device programmer consists of an electromagnetic programming head that is placed over the implanted device and provides through-the-skin communication with the implanted device, the personal computer (PC) interface, and the PC hardware and software. The programmer permits the physician-user to:

OTS Software: An OTS operating system such as DOS or Windows is used to provide a user interface (sometimes graphical), interface to the PC (hardware platform), and interface with data storage, and output devices.

OTS Software Level of Concern: The on-board software for the implant satisfies the definition of Major Level of Concern software (life supporting/life sustaining) and would need to satisfy the Special Documentation (see Section V.E). Whether the device programmer can be considered of lesser Level of Concern depends primarily on the protection designed into the implant or the programmer. Steps taken to mitigate the risk might include: