Software As A Medical Device (SaMD) is software made for one or more medical uses without requiring a medical hardware device for its use. The International Medical Device Regulators Forum (IMDRF) defines SaMD as software intended to be used for one or more medical purposes that perform these purposes without being part of a hardware medical device. Software as a Medical Device (SaMD) is one of three types of software associated with medical devices. The other two types of software are software in medical devices and software for manufacturing or maintaining medical devices.
SaMD products are sets of algorithms operating with data inputs to produce outputs for medical purposes as defined by the products manufacturer. Risks associated with SaMD products include risks posed by inaccurate input data and/or incorrect output of the SaMD product impacting the clinical management of healthcare practices.
Basic programming model of a SaMD product.
According the International Medical Device Regulators Forum (IMDRF) key definitions of Software as a Medical Device (SaMD) include the following:
- SaMD is capable of running on general purpose (non-medical purpose) computing platforms
- “Without being part of” means software not necessary for a hardware medical device to achieve its intended medical purpose
- Software does not meet the definition of SaMD if its intended purpose is to drive a hardware medical device.
- SaMD may be used in combination (e.g., as a module) with other products including medical devices
- SaMD may be interfaced with other medical devices, including hardware medical devices and other SaMD software, as well as general purpose software
- Mobile apps that meet the definition above are considered SaMD.
Examples of software that is not Software as a Medical Device (SaMD), but may be mistaken as SaMD include:
- Software 'part of' or used to 'drive or control' motors, pumping actions, or closed loop control systems for implantable medical devices (i.e pacemakers); these types of software are referred to as 'embedded software', 'firmware', or 'microcode', and are not SaMD
- Medical devices requiring software to perform their intended use even if the software required for their use is sold separately from the medical device itself
- Clinical communication software for patient registration, scheduling, and telemedicine
- Software relying on information provided by medical devices without any medical purpose, such as software for encrypting patient or clinical data transmitted by a medical device
- Software for monitoring the performance of medical devices, such as predicting when to replace x-ray tubes based on their performance or integrating and analyzing laboratory quality control data for identifying random errors or calibration trends for in virto diagnostics (IVDs)
- Software generating inputs useful for SaMD products that do not have any medical purpose are not considered to be SaMD; for example, a database for searching and querying medically relevant data is not a SaMD even when it's being used by a SaMD product
There are three main categories of SaMD products:
- Treating and/or diagnosing disease
- Driving clinical management
- Informing clinical management
SaMD products made for treating and/or diagnosing disease are used to take immediate or near term actions in clinical settings. They are connected to other medical devices, medicinal products, general purpose actuators, or other means of providing a form of therapy to human patients to treat or mitigate disease. SaMD products made for diagnosis, screening, and detecting disease are made to infer information gathered by sensors, healthcare data, or other information from any hardware or software device relevant to a disease or condition.
SaMD products for driving clinical management are made to aid patient treatment, patient diagnosis, patient triage, and help medical professionals identify the early stages of a disease or conditions for the next diagnostic or treatment interventions requiring immediate or near term intervention. These products provide enhanced support for safely and effectively using medical devices and medical products on patients by medical professionals, and to help analyze relevant patient information to more accurately predict disease diagnosis and disease risk.
SaMD products for informing clinical management differ from products made for driving clinical management because they aim to provide information not leading directly to immediate or near term action to treat, diagnose, or predict disease. These products help inform medical professionals about the options available for treating, diagnosing, preventing, or mitigating a specific disease or condition, and help aggregate relevant clinical information, such as information related to the disease, condition, drugs, medical devices, patient populations, and other relevant information, for analysis by medical professionals.
SaMD products are made for use in at least one or more of three distinct healthcare situations:
- Critical situation or condition
- Serious situation or condition
- Non-Serious situation or condition
A critical situation or condition requires immediate and/or time efficient treatment or diagnosis to avoid serious patient deterioration, long-term disability, death, or serious impacts to overall public health. SaMD products are used in a critical situation or condition where there is a life-threatening state of health, a major therapeutic intervention is required, the patient is in a highly fragile state, or the success of medical intervention is time critical.
SaMD products made for use in critical situations or conditions are intended to be used by people with specialized training using the SaMD product.
A serious situation or conditions is when the accurate treatment or diagnosis of a patient is important for avoiding interventions that are not necessary, or making timely interventions that mitigate the risk of irreversible patient or public health outcomes. SaMD products for serious situation or conditions are used when a patient is in a life-threatening state of health, a major therapeutic intervention is required, the required intervention is not immediately needed to avoid undesirable health outcomes (death, long-term disability, or serious health deterioration), or the patient is not in a fragile state in relation to their disease or medical condition.
SaMD made for serious situations or conditions are intended to be used by both specially trained users and lay users. When SaMD products made for serious a serious situation or condition is used by a person without specialized training, and without support by someone who is specially trained to use the software, the SamD product is considered to be used in a critical situation or condition; not a serious situation or condition.
A SAMD product for use in a non-serious situation or condition where an accurate diagnosis or treatment is important but not critical for preventing negative irreversible health consequences for patient or public health. SaMD products for non-serious situations or conditions are used when there is a slow and predictable disease or condition progression, effective management of the disease or condition is possible, or a minor therapeutic intervention is required that is normally noninvasive.
The intended target population of SaMD products for non-serious situations or conditions are meant for individuals aware of their conditions and individuals who are unaware of their condition, and may be used by individuals with specific training or no training using the SaMD product.
All three situations faced by SaMD products (critical, serious, and non-serious) are categorized in four categories (I, II, III, IV). Category IV has the highest level of impact and level I has the lowest.
SaMD categories.
All categories of SaMD products attempt to take into account all relevant factors contributing to patient safety to ensure positive patients outcomes. SaMD products attempt to understand how their use impacts the potential to lower or raise hazardous situations face by patients in complex clinical environments. Examples of aspects influencing patient safety in relation to SaMD products include:
- Type of disease or condition
- Patient fragility in relation to their disease or condition
- Progression and stage of disease or condition
- Usability of SaMD product
- Product design towards a specific user type
- Amount of user reliance based on the output of the SaMD product
- Transparency of the inputs, outputs, and methods of the SaMD product to the user
- Types of output information and the level of influence they have on clinical interventions
- Complexity of clinical models used to create the output information
- Known specificity of output information
- Maturity of clinical information used to determine output information and level of confidence in output information
- Benefit of output information in relation to patient baseline
- Technical characteristics involved in the overall operation of the SaMD platform
- Software distribution methods
SaMD regulation requires all stakeholders and regulators to ensure the promotion of safe innovation practices and patient safety. The IMDRF formed the Software as a Medical Device Working Group, chaired by the Food and Drug Administration (FDA), in 2013 with the goal of developing a global guidance strategy for increasing safe innovation, patient accessibility, and patient safety related to SaMD. The Software as a Medical Device Working Group and the FDA agreed upon key definitions, a framework for risk categorization, quality management systems, and clinical evaluation of SaMD products.
The clinical evaluation of SaMD products are based on three primary factors:
- There is a valid clinical association between the SaMD product and the SaMD's targeted clinical condition (valid clinical association)
- The SaMD product correctly processes and generates accurate, reliable, and precise output data (analytical validation)
- The SaMD product achieves its intended purpose accurately, reliably, and precisely in the context of the clinical care of a target population (clinical validation)
Valid clinical evaluation, also called scientific validity, of SaMD products refers to the products output being clinically accepted (or based on a body of scientific evidence) and corresponding accurately to the patients condition or healthcare situation designed to be addressed by the SaMD product. A valid clinical association helps indicate what level of clinical acceptance should occur and how much confidence can be assigned to the output of the SaMD product for its intended use in healthcare situations.
Analytical validation objectively measures the ability of the SaMD product to produce accurate, reliable, and precise technical output data based on its input data. If the SaMD products does consistently reproduce accurate, reliable, and precise technical outputs based on its input data then the SaMD product is considered to meet its specifications and conform to the needs of its users and intended use. The analytical validation phase occurs within the verification and validation phase of the software development lifecycle and is performed by the manufacturer of the product using a quality management system.
Clinical validation of a SaMD products is defined as a set of ongoing activities conducted in the assessment and analysis of its clinical safety, effectiveness, and performance as intended by the manufacturer of the SaMD product in its definition statement. Examples of measurements made for clinically validating SaMD products include: sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), number needed to treat (NNT), number needed to harm (NNH), likelihood ration negative (LR-), likelihood ratio positive (LR+), odds ratio (OR), clinical usability/user interface, and confidence interval.
An independent review of a SaMD products clinical evaluation is important to establish the level of impact the SamD products has on patients and public health through its ability to treat or diagnose and influence clinical management decisions. Independent reviews are important to improve the clinical confidence and evaluation of SaMD products by attempting to identify design errors, product limitations, broadening the technical competence of the product, testing appropriateness of assumptions made by the product, and managing bias present in the functioning of the product. The goal of subjecting SaMD products to an independent review is to gain a better understanding of the products risks and definition statement.
Risk based approach to importance of independent review.
