Manufacturers of home healthcare devices face a daunting product requirements challenge. Whether developing a new product or transitioning one from the clinic into the home, developing products for home healthcare entails recognizing, understanding, and mitigating a vast number of differences between home and clinical healthcare paradigms—differences that often lead to consequences that cannot be taken lightly, such as conflicting or poorly defined requirements, particularly when not well understood by all stakeholders.

For marketing and product management, conflicting and poorly defined requirements often cause missteps and rework, resulting in longer development schedules. For human factors and design, conflicts risk the development of a device that accommodates technologies and costs, rather than supporting the user and the treatment goals of the device, resulting in a less usable product that may fail to achieve certification from regulatory bodies due to increased risk, and one that fares poorly in the market. For engineers, aggressive product cost, quality, and development schedule goals may be missed.

Compared to medical professionals, home users are likely to be less experienced and knowledgeable about their device, the medical condition it is intended to treat, and how it operates. They are likely to be lacking the general medical knowledge and experience that allows medical professionals to quickly train on a new device. They may be less inclined to use advanced features of interest to medical professionals, and be more interested in their own circumstances rather than the potential range of their medical condition.

Compared to medical professionals, home users are likely to be less experienced and knowledgeable about their device, the medical condition it is intended to treat, and how it operates.

Depending on the condition being treated and the expected user population, home users may be faced with cognitive, sensory, and physical impairments caused by aging or their condition. They are more emotionally invested in the treatment, thus may experience a greater amount of stress when dealing with off-normal conditions. These differences between professional and home environments necessitate the development of design requirements that mitigate such user issues.

Similarly, the home environment brings other differences: the need for portability; different sterilization practices and standards; and different resources, including support equipment, processes, and personnel that require implementations specific for home use. Differences that relate to the device itself must also be addressed through well-defined requirements. These differences include: appropriate size and weight, expected battery and backup life, anticipated product life (including refurbishing for resale), availability of interfaces to other devices and systems for record keeping or alerts and alarms, the use and management of consumables and disposables, regulatory classifications, noise, and many more.

Trade-offs and compromises between engineering, human factors and design, and product management requirements that attempt to address these paradigm differences are inherent, but there are also opportunities for innovative solutions. Technology can quickly change both what is possible and what is expected of a device. The ability to understand these issues and make the right decisions is the key to developing a successful product. All approaches necessitate a thorough understanding of the market, user needs, use environment, technology, engineering, regulatory, human factors, training, support, cost, schedule, risk, and manufacturing issues that cannot be achieved through a siloed approach. An interdisciplinary team, following a structured approach and sharing common goals is the best path to success.

Trade-offs and compromises between requirements that attempt to address home use are inherent, but there are also opportunities for innovative solutions.

In any product development process, three functions represent the key roles necessary for successful product development. Marketing/product management must address the questions of what needs the product will address; who will buy it; what the market size and value are; what competing devices will be studied; what the lifecycle will be from sale to disposal; and which design, regulatory, manufacturing, training, support, and service schedules and costs will result in an attractive business model.

Human factors and design must be used to address the issues of who will use the product and how tasks will be accomplished; they must identify the use cases, and understand the use environments and what will be required from the user and the device to accomplish the intent. Design extends to outlining the form of the product requirements that meet these needs but does not necessarily extend to how the requirements are implemented.

Engineering must identify the technologies, components, and performance specifications that are required to meet the needs after they are defined, and how they can be implemented within the constraints of the business model, including assessments for cost, risk, and schedule. These functions may be filled by groups or individuals within the organization, or may be outsourced to subject experts and consultants.

An interdisciplinary, user-centered approach utilizing the principles and techniques of design thinking and design research results in the convergence of requirements. Design thinking is an inherently user-centered method of practical, creative identification and resolution of problems or issues. The better the team understands the user's needs and desires, the more successful the final product will be in regulatory review, patient compliance, outcomes, and the market. This process includes exploring existing products and technologies, including those of other fields, and developing insight into how they can contribute to innovative—even disruptive—solutions.

The standard Medical devices – Application of usability engineering to medical devices (ANSI/AAMI/IEC 62366:2007, Annex D)1 details a user-centered design approach to ensure that medical devices, including those intended for home healthcare, are designed for usability and for the safety of the user. The process also emphasizes the need for user research to be conducted throughout the design cycle once the therapy has been validated by clinical research: from exploratory research conducted before any product development decisions are made, through validation of the design approach and verification of implementation, through post-market surveillance to mediate any undetected issues.

In effect, this argues for the involvement of the designer in all phases of the product development lifecycle: The designer is the steward of the user's needs and desires, often either conducting the research that informs these decisions or being closely involved with those who do. To ensure that requirements address the needs of the user without overly constraining the implementation, engineers should also be involved throughout the design phases and be intimately aware of the research that informs the requirements. Product management should take an active part in design and user research to ensure that the product requirements represent the full, intended use market and do not become too narrow or uncompetitive.

It is the designer's mission to understand the user population and scenarios of use defined by product management, converting them into requirements. It is the engineer's charge to actualize design requirements based on those needs in a way that meshes with product business requirements set by product management. Often one camp sees the others as just not “getting it” – but the “it” differs; designers don't “get” the myriad trade-offs and limitations inherent in the engineer's world, and engineers don't “get” those based on the user. Marketing does not understand why design and engineering are so slow and complex when the world is filled with impressive very low-cost, high-tech consumer products (that are not subject to long regulatory reviews and do not require the reliability and longevity of medical devices.)

Often one camp sees the others as just not “getting it” – but the “it” differs; designers don't “get” the myriad trade-offs and limitations inherent in the engineer's world, and engineers don't “get” those based on the user.

Both designers and engineers feel pressured by overly aggressive schedules, features, and cost goals. This is often the result of organizations and individuals operating in silos, in which each function accomplishes the tasks assigned in isolation, resulting in a “throw-it-over-the-wall” transaction. An interdisciplinary effort utilizing design thinking principles and techniques brings designers, engineers and product managers together in such a way that each is privy to and understands the factors that drive the others.

For this approach to be effective, it is important for all involved to step away from the preconceived notions that they hold about the users, product, market, technology, engineering, software, regulatory, cost, schedule, and corporate history that inhibit innovation and creativity. By focusing on the shared goal of identifying and implementing the best (right) product, a team can more efficiently work together, streamlining development and regulatory reviews, especially when empowered with organizational commitment and appropriate decision-making authority.

One of the most effective means to accomplish the development of a shared goal is to ensure that product managers, engineers, and other stakeholders participate in user engagements early in the process. Too often, designers and human factors specialists are the only stakeholders actively engaged with the user. Obviously, it is the designer's task to develop a keen understanding of the user, his goals, the obstacles that may lie ahead, and his needs and wants when accomplishing the application.

However, the results of this siloed approach are design requirements crafted during exploratory research that satisfy the user-side of design by offering solutions presented as take-it-or-leave-it requirements that do not match marketing's vision and/or that prove difficult for engineering to actualize within the project constraints. Utilizing an interdisciplinary approach during this early user research phase helps to ensure a common understanding and enhances communication between the functions. The result is that requirements accurately distill the core needs of the user, without introducing unnecessary engineering constraints, and ensures requirements that mesh well with engineering implementations.

Utilizing an interdisciplinary approach during early user research phase helps to ensure a common understanding and enhances communication between the functions.

As an example of the conflict between the human factor and implementation, consider devices that include a graphic display. Lower margins, long battery life, and reduced interface complexity may lead the product management to desire the use of a smaller display, but if the product is intended for use by older patients with aging eyes the designer will likely suggest a larger display. Through the inclusion of an interdisciplinary team following a structured requirement development process, it is often possible to re-cast the conflicting requirements into an uncompromised solution. In this example, cost and battery life are on one side, with human factors and broad user population on the other. This conflict is the result of a complex set of assumptions involving the product features, user interface, user demographics, intended use(s), competitive and market influences, technology, cost, schedule, risk, and complexity.

The purpose of an interdisciplinary design process is to avoid these hidden assumptions before dealing with the more fundamental elements of the requirements. This opens the solution up to the appropriate mix of approaches and technologies that are available and understood by the interdisciplinary team, including disruptive solutions. The answer is not to compromise on the size of a display, but to understand the intended use application, user population, use environment, available technologies, costs, engineering risks and complexity, and regulatory requirements to develop the right product requirements.

In the case of screen size, important options for discussion might include improved information presentation, fixed labels versus dynamic screen content, buttons versus touch screen, pre-set versus configurable settings, daylight readability and backlight brightness, monochrome versus color, dedicated function indicators, and user needs versus support and service needs. Once these issues are exposed, engineering and technology can be added to the discussion to cover the cost, complexity, risk, performance, support, service, and product life impacts of the various solutions.

As an example of the need for the requirements of the user meshing well with the engineer's implementation, consider the common push from product management to include the latest technology in a device.

In this process, screen size is simply not a requirement worthy of discussion until the underlying requirements for functions, readability, fixed versus dynamic content, and use environment have been resolved. Technology options like wireless connectivity to smart devices or to remote monitoring, service, and support capabilities can be added to the team discussion, where the common goal and interdisciplinary expertise leads to efficient and innovative decisions.

Once this has been done, the size, type, sourcing, and cost of the screen options, if one is needed, can be resolved based on business and market inputs without compromising function, as long as the display meets the underlying requirements. As engineering proceeds with implementation, the detailed understanding of the users, scenarios of use, and motivations that resulted in the requirements informs the detailed engineering decisions, minimizing the risk that the device will have verification problems.

As another example of the need for the requirements of the user meshing well with the engineer's implementation, consider the common push from product management to include the latest technology in a device. An interdisciplinary approach enables design and human factors or engineering to convey the risk of doing so. A multi-touch interface utilizing complex gestures, though appealing from a marketing perspective, may be inappropriate for user populations not accustomed to their use or for users with physical limitations, such as diabetic neuropathy, that inhibit their use. Conversational voice-driven interactions, though leading to impressive demonstrations, require high processing capabilities and still prove too frustrating for broad use.

The challenges of developing the right set of requirements for a home healthcare device are significant and require techniques that address engineering, regulatory, and business concerns, while designing for the needs of the broader and more diverse user population and environments in home care. While the high level processes and procedures are similar to those already utilized by many manufacturers of medical devices, the interdisciplinary team approach advocated here and the techniques required to make it effective and efficient are new to most development teams. The time and effort needed to implement such an approach are negligible when compared to the cost of false starts, rework, and product failures that otherwise result when conflicting requirements fail to articulate the fundamental needs of the users, the environment, and the application.

ANSI/AAMI/IEC 62366:2007
Medical devices –Application of usability engineering to medical devices.
Association for the Advancement of Medical Instrumentation
Arlington, VA

About the Authors

Carolynn R. Johnson, PhD, is human factors and research manager at Daedalus, Pittsburgh, PA. E-mail:

R. Craig Campbell is lead electrical engineer at Daedalus, Pittsburgh, PA. E-mail: