Accessibility is becoming an increasingly important consideration in home healthcare due to changing user demographics, an emphasis on baby boomers, and the greater number and complexity of devices being used outside clinical environments. Medical device accessibility is defined as the degree of “ability to access” or benefit from the intended uses of devices within environments. Accessibility includes consideration of diverse users with functional limitations and analysis of barriers to use.12 Medical device accessibility can address diverse user needs related to receiving and providing safe and effective home healthcare.The number of home healthcare recipients will likely continue to increase as the U.S. population ages, which also means more devices will be used outside of clinical settings.3 In 2010, about 12 million individuals received home healthcare, and this number will increase to 27 million by 2050.4 Along with professional caregivers, about 52 million informal and family caregivers provide care for others. Unpaid family caregivers likely will remain the largest long-term care provider group, reaching about 37 million caregivers by 2050.5Home healthcare will continue to grow as we are “sending people home sicker and quicker” to manage their health conditions, while “devices [are becoming] a frequent sight in the home” according to Mary Weick-Brady, U.S. Food and Drug Administration (FDA) senior policy advisor. Lay users are increasingly using devices that were not designed for use in nonclinical environments, and home-based medical procedures are becoming more complex, including dialysis and intravenous therapies.Therefore, increased emphasis on development of safe and effective medical devices by applying accessibility and human factors considerations for a broad spectrum of users and environments is necessary to improve the overall quality and safety of home healthcare. Overall, observing FDA draft guidance for applying the human factors process to medical device and product design is a good starting point for creating safer and more effective devices for end users.678 There are numerous human factors methods, publications, and findings that also relate to the safe and effective design of home healthcare devices, however discussion of these resources is beyond the scope of this paper so they are not discussed here.In recent years, more than 19,000 adverse events in home healthcare were reported to the FDA, which were attributed to challenges such as environmental hazards (e.g., power overload or failure), poor usability, and unsafe devices (e.g., insufficient labeling, complex displays, lack of easy-to-understand troubleshooting guidance).9With respect to accessibility, Molly Follette Story, FDA human factors and accessible medical technology specialist says, “FDA wants to know who's using the device; and for human factors, we want to make sure that the people who are identified as being users can use the device safely and effectively. It relates to the match between the capabilities of the user, the knowledge of the user, and the demands of the device. As an agency, we can help make people aware of different user populations and the types of interface attributes that cause problems, ways to address those, and features that make interfaces easier and safer to use, and more accessible for more people. I really think if industry knew how simple this can be in some cases, they would do more to accommodate broader user populations.”Accessibility is typically considered for people with diagnosed disabilities from conditions such as spinal cord injury or blindness. Older adults also benefit from accessible designs. However, when considering home healthcare devices and lay users, “disabilities” can exist due to environmental factors or other nonconventional user limitations.Figure 1 compares two conceptual models for thinking about accessibility applied to home healthcare devices. Figure 1A represents more common thinking about users with diagnosed disabilities, such as older adults or users who are blind, being a minority user population for whom accessible design needs exist. Common thinking relegates people with disabilities to the lower end of the skewed normal distribution, and the majority of device users are nondisabled. Classic thinking suggests that accessible design is helpful for a limited number of users.Figure 1B represents more realistic thinking about users with “disabilities” or functional limitations that can be caused by user or environmental limitations in home healthcare. Here, the normal distribution is shifted towards lower functional abilities. By considering nontraditional users and environmental limitations that emerge in home healthcare, it can be seen that a majority of users can benefit from accessible design in home healthcare. Examples of lay user abilities, disability diagnoses, and potential disabling factors in home healthcare that can present as functional limitations with regards to device use are provided in Table 1.Home healthcare users are diverse in age, backgrounds, and abilities, with 69% of the 12 million lay caregivers being 65 or older6 and likely experiencing their own functional limitations due to aging (e.g., decreased strength, vision and hearing loss). Many caregivers face nonhealthcare-related life demands, such as being employed in addition to their caregiving roles.1011 Lay caregivers are at increased risk for physical and mental health issues,1213141516 especially with potential emotional impacts from learning about a diagnosis, navigating a care plan, and providing unsupervised healthcare with complex medical devices.Some common emotional reactions include difficulty concentrating, memory loss, and decreased processing and problem-solving capabilities. 171819 Therefore, although users with severe functional limitations may not initially be intended to use devices independently, it is important to consider human factors that could cause physical, sensory, and cognitive limitations for users in home healthcare.Some of the unique factors of home healthcare environments, such as diverse noise and lighting conditions of the outdoors or workplaces, can also cause users to experience “disabilities.” Weick-Brady explains that home healthcare devices include “devices in a nonclinical environment being used by somebody who is not a healthcare professional.” Home healthcare environments are unpredictable compared to clinical settings, and lay users might not understand environmental risk factors, such as lighting, noise, or sterility and their potential negative impacts.According to Story, “Environmental issues are something that manufacturers often don't take into consideration as much as they should.” Therefore, it is important for manufacturers, healthcare providers, and patients to work together to better understand the risks and improve designs for home healthcare.Accessibility literature relevant to medical device design can be referenced from different disciplines such as engineering, rehabilitation, and occupational therapy. Specific minimum accessibility guidelines and standards also exist, including a few targeted to medical device design and home healthcare. Forthcoming guidance is also likely due to FDA's Home Healthcare Initiative, as well as the development of AAMI's TIR49, Design of training and instructional materials for medical devices used in non-clinical environments. Some accessibility guidance relevant to home healthcare is provided in Table 2.Beyond applying human factors and accessibility methods to the design process, the following general accessibility considerations for home healthcare devices and lay users can help create safer and more accessible devices.Home healthcare devices are used by a diversity of users operating within highly variable environments. Therefore testing devices early and often with users with disabilities is beneficial for understanding potential lay user risk profiles. Because many user-environmenttask interactions in home healthcare can closely mimic performance characteristics of people with disabilities, evaluating devices with these users helps drive design decisions to improve safety and use.When recruiting participants, it is often acceptable to group people with similar functional limitations that might manifest from different diagnoses, especially when trying to understand the diversity of potential risks that may exist for home healthcare devices. Disability experts can be useful for informing design teams about potential risks for people with disabilities, but should not replace the observation of people with disabilities interacting with devices.Therefore, even if devices are not necessarily intended for users with disabilities, there is benefit in observing the alternative performance strategies of these users, talking to people with disabilities, and learning more about potential risks for users with impairments that could apply to other users, use scenarios, and environmental characteristics.Many lay users in home healthcare have coexisting functional limitations. For example, it is practical that someone who is aging with diabetes might have tremor, strength, and grasping difficulties from aging as well as retinopathy and neuropathy from diabetes. People with disabilities also frequently use assistive technologies to enhance their function such as eyeglasses, canes, and hearing aids, which should be considered as part of the lay user profile for home healthcare devices.For example, devices intended to monitor people as they sleep could be tested in a darkened room while participants are not wearing glasses to better simulate a scenario of an alarm state occurring as a caregiver is awakened from sleep. Observing performance strategies developed by people with disabilities, such as assembling a device by someone with arthritis or tremor, can help manufacturers learn potential alternative task strategies utilized by users with functional limitations. This could ultimately lead to device designs with decreased task demands for all users. Testing scenarios and users with functional limitations can help manufacturers create safer designs for home healthcare.Finally, the limitations of disability simulation techniques for understanding user performance characteristics need to be realized. Disability simulation, such as having people wear sight-reducing goggles or earplugs, can help inform designers what it could be like to use devices with decreased abilities. However, simulation does not provide user performance data representative of users with functional limitations or opportunities to discuss any observed use errors. Simulation fails to represent impairments correctly and does not address potential coping strategies or skills that people can develop when living with disabilities.20 Therefore, disability simulation techniques are recommended for early conceptual discussions. Observing real users with functional limitations interacting with designs is key to obtaining better understanding of user performance and risks.Homes and other informal healthcare settings represent incredibly diverse and complex environments. Lay users more often encounter devices well suited for professional users and inpatient settings, which become difficult to use outside of clinical settings. Ultimately, the unique nature and diversity of users and environments in home healthcare cause human factors challenges that need to be adequately addressed to improve patient and user safety.For example, many home healthcare devices are used in relatively dark settings, especially in traditional homes as compared to clinical environments. In a formative analysis of a device with an LCD display used by emergency medical technician (EMT) workers under sunlight and spot lamp indoor lighting conditions, most participants commented that the display had poor readability and mentioned the importance of backlighting and high contrast for displays in the home. Understanding “worst case” environmental interactions in home healthcare can help improve product labeling, training, and device use to positively impact patient and user safety.Flexible or adjustable designs help address the diversity of users and environments in home healthcare. For example, audio displays with adjustable volume might be thought of as critical for users with age-related hearing loss or ear infections. But users operating devices in homes with the windows open and fans running on a hot day, or in a crowded restaurant, might experience similar hearing limitations due to environmental characteristics. Therefore, designs that include adjustable features can benefit large proportions of home users and environments.Redundant formats for product labeling are important for devices that depend on effective labeling, training, and practical troubleshooting tips. In home healthcare, product labeling could be the only mitigation available to end-users in times of need, for example when clinical facilities are closed or experienced device users are unavailable. Printed instructions for use could be supplemented with other labeling, such as web-based instructions for use or video-based troubleshooting tips. Redundant labeling formats help users with visual limitations who might not be able to read traditional printed text; users who cannot find printed documentation; users in different locations than their documentation; or users needing interactive guidance to understand device processes, such as calibration or repair.Performance-based user prompts are important for home lay users who are often not medically trained. Therefore, informative user prompts can guide lay users through complex task sequences involving multiple steps. For example, accessible prompts on a display to help lay users discover and eliminate a line occlusion go beyond using readable fonts and simplified terminology, such as “blocked flow” instead of “line occlusion.”More accessible designs need to provide meaningful alerts and performance-based prompting for action steps, such as “Check for blocked flow. Remove blockage and restart.” Otherwise, lay user confusion about seemingly common procedures could leave users unaware of critical steps required after an alert is acknowledged. Therefore, accessible alerts, alarms, and user prompts need to provide timely, detailed, understandable, and user performance-based information.According to Story, addressing home healthcare risks is “a shared responsibility among the agency, manufacturers and medical providers for the health and safety of the patient.” Weick-Brady explains that it includes “practitioners taking more responsibility for who their patient is, or demanding devices that are designed based on what their individual patients need. Patients need to be more demanding for products that are designed more for ease of use. And manufacturers need to be more attuned to whom they're selling their devices to and knowing that their devices are probably going into the hands of somebody who is not a prescriber or not a healthcare professional.” Ultimately, accessible design can address the diversity of user and environmental characteristics that confound the complex risks associated with home healthcare devices, which will help to improve the health and safety of patients and lay users.The authors thank Mary Weick-Brady, senior policy advisor at the Office of the Center Director, CDRH, FDA, and Molly Follette Story, human factors and accessible medical technology specialist, CDRH, FDA, for their Sept. 21, 2012 interview.