Limitations
depression, cognitive impairment, anxiety
MINOR, RECRUITMENT, ATTRITION
This study has several limitations. First, it was not a randomized controlled trial but rather a pre-post pilot study. Hence, we did not have any control for potential natural changes in the outcome measures over time, although we would not expect the measures to improve without intervention. All questionnaires had high test-retest reliability, indicating stability over time [Another limitation was the use of a convenience sample, which was highly educated, had high levels of computer literacy, and limited cultural diversity. An important next step will be to target recruitment more widely and examine the feasibility and acceptability for people with less education and computer literacy and more varied cultural backgrounds. The consideration of providing further support to engage older adults with less familiarity with technology [In terms of strengths, the OPTIMiSE pilot did reach some rural residents, enabling participation by those who would not have been offered a face-to-face group. It also enabled scale of economy by delivering content to over 300 participants, rather than to 8 to 12 participants in a typical in-person group intervention. Moreover, much of the content would be used in future renditions of OPTIMiSE. In terms of sustainability, as delivered in this study, OPTIMiSE has some ongoing costs related to participant recruitment and support and the sections of the course that involve interaction (discussion boards, weekly summaries, and end-of-course panel discussion). Compared with a synchronous intervention, which would also require ongoing costs related to participant recruitment and support, as well as facilitator time, these costs are likely to be minimal.Although attrition was similar to that observed in other web-based studies, it was high compared with that observed for in-person interventions. Attrition may be reduced by providing more information to participants before registration for the intervention (as many participants withdrew before giving consent) and providing accurate information regarding the duration of modules, given that the length required was a commonly suggested improvement. More flexibility around time to complete the course may also assist, given the lower attrition rate observed in another web-based memory study without a fixed time frame [Attrition impacts our primary measures of acceptability, which were administered at the end of the course and hence completed by only those who finished the course. Thus, we can only confidently state that the program was acceptable to the completers. Having data only from intervention completers is a common issue in determining the acceptability of an intervention. We tried to account for this by asking those who withdrew to complete a short web-based form providing the reasons for withdrawal, which provided us with some data; however, this form was only completed by 18.3% (24/131) of participants. We did gather information about acceptability along the way through feedback on each individual module (Participant feedback suggests that only minor tweaks are necessary for future revisions of OPTIMiSE. These include reducing the length of modules where possible, providing accurate information about the expected time commitment for each module (especially those with more content), providing handouts throughout the course, and revamping some of the expert interviews to be less technical. Further adaptations may be needed for different target groups, for example, older adults with greater memory difficulties (such as those with mild cognitive impairment) and those from more diverse cultural backgrounds. Conversely, OPTIMiSE may be most suited for older adults dwelling in the community, with subjective concerns but only minimal objective changes in their cognition. It may fit as an early or low-intensity intervention within a stepped or staged care model, akin to the models used for the treatment of anxiety and depression, which are especially useful for those living in rural communities [