BACKGROUND
E-health applications are an avenue to improve service responsiveness, convenience, and appeal, and tailor treatments to improve relevance, engagement, and use. It is critical to user engagement that the designs of e-health applications are intuitive to navigate. Limited research exists on designs that work for those with a severe mental illness, many of whom infrequently seek treatment, and tend to discontinuation medications and psychosocial treatments.
OBJECTIVE
The purpose of this study was to evaluate the influence of 12 design elements (e.g., website depth, reading level, use of navigational lists) on the usability of e-health application websites for those with, and without, mental health disorders (including severe mental illness).
METHODS
A 212-4 fractional factorial experimental design was used to specify the designs of 256 e-health websites, which systematically varied the 12 design elements. The final destination contents of all websites were identical, only the navigational pages varied. Three subgroups of participants comprising 226 individuals, were used to test these websites (those with schizophrenia-spectrum disorders, other mental illnesses, and no mental illness). Unique to this study was that the 12 design elements were manipulated systematically to allow assessment of combinations of design elements rather than only one element at a time.
RESULTS
The best and worst designs were identified for each of the three subgroups, and the sample overall. The depth of a website’s navigation, that is, the number of screens/pages users needed to navigate to find desired content, had the strongest influence on usability (ability to find information). The worst performing design for those with schizophrenia-spectrum disorders had an 8.6% success rate (ability to find information), the best had a 53.2% success rate. The navigational design made a 45% difference in usability. For the subgroup with other mental illnesses the design made a 52% difference, and for those with no mental illness a 50% difference in success rate. The websites with the highest usability all had several key similarities, as did the websites with the poorest usability. A unique finding is that the influences on usability of some design elements are variable. For these design elements, whether they had a positive or negative effect, and the size of its effect, could be influenced by the rest of the design environment, that is, the other elements in the design. This was not the case for navigational depth, a shallower hierarchy is better than a deeper hierarchy.
CONCLUSIONS
It is possible to identify evidence-based strategies for designing e-health applications that result in a high level of usability. Even for those with schizophrenia, or other severe mental illnesses, there are designs that are highly effective. The best designs have key similarities, but can also vary in some respects.
Key words: schizophrenia, severe mental illness, e-health, design, website, usability, website design, website usability, fractional factorial design.
