To understand the mechanism involved in the apical sorting of glycosylphosphatidylinositol (GPI)-anchored proteins (GPI-APs) we fused to the C-terminus of GFP the GPI-anchor-attachment signal of the folate receptor (FR) or of the prion protein (PrP), two native GPI-anchored proteins that are sorted apically or basolaterally, respectively, in MDCK cells. We investigated the behaviour of the resulting fusion proteins GFP-FR and GFP-PrP by analysing three parameters: their association with DRMs, their oligomerisation and their apical sorting. Strikingly, we found that different GPI-attachment signals differently modulate the ability of the resulting GFP-fusion protein to oligomerise and to be apically sorted. This is probably owing to differences in the GPI anchor and/or in the surrounding lipid microenvironment. Accordingly, we show that addition of cholesterol to the cells is necessary and sufficient to drive the oligomerisation and consequent apical sorting of GFP-PrP, which under control conditions does not oligomerise and is basolaterally sorted.

Background There is currently limited evidence on the level and intensity of physical activity in individuals with hemophilia A. Mobile technologies can offer a rigorous and reliable alternative to support data collection processes but they are often associated with poor user retention. The lack of longitudinal continuity in their use can be partly attributed to the insufficient consideration of stakeholder inputs in the development process of mobile apps. Several user-centered models have been proposed to guarantee that a thorough knowledge of the end user needs is considered in the development process of mobile apps. Objective The aim of this study is to design and validate an electronic patient-reported outcome mobile app that requires sustained active input by individuals during POWER, an observational study that aims at evaluating the relationship between physical activity levels and bleeding in patients with hemophilia A. Methods We adopted a user-centered design and engaged several stakeholders in the development and usability testing of this mobile app. During the concept generation and ideation phase, we organized a need-assessment focus group (FG) with patient representatives to elicit specific design requirements for the end users. We then conducted 2 exploratory FGs to seek additional inputs for the app’s improvement and 2 confirmatory FGs to validate the app and test its usability in the field through the mobile health app usability questionnaire. Results The findings from the thematic analysis of the need-assessment FG revealed that there was a demand for sense making, for simplification of app functionalities, for maximizing integration, and for minimizing the feeling of external control. Participants involved in the later stages of the design refinement contributed to improving the design further by upgrading the app’s layout and making the experience with the app more efficient through functions such as chatbots and visual feedback on the number of hours a wearable device had been worn, to ensure that the observed data were actually registered. The end users rated the app highly during the quantitative assessment, with an average mobile health app usability questionnaire score of 5.32 (SD 0.66; range 4.44-6.23) and 6.20 (SD 0.43; range 5.72-6.88) out of 7 in the 2 iterative usability testing cycles. Conclusions The results of the usability test indicated a high, growing satisfaction with the electronic patient-reported outcome app. The adoption of a thorough user-centered design process using several types of FGs helped maximize the likelihood of sustained retention of the app’s users and made it fit for data collection of relevant outcomes in the observational POWER study. The continuous use of the app and the actual level of engagement will be evaluated during the ongoing trial. Trial Registration ClinicalTrials.gov NCT04165135; https://clinicaltrials.gov/ct2/show/NCT04165135

BACKGROUND Mobile technologies can offer a high potential solution to increase the rigorousness and reliability of data collected within clinical studies. However, the development process of mHealth apps is often inadequate and not sufficiently participatory, affecting the potential to meet intended purposes. OBJECTIVE The aim of this study was to design and validate a mHealth app for physical activities and electronic patient-reported outcomes (ePRO) collection in the POWER observational study currently enrolling patients with haemophilia A. METHODS We adopted a user-design process grounded in design science engaging several stakeholders in the development and usability testing of this mobile application, measured through the mHealth app usability questionnaire (MAUQ). During an initial need-assessment focus group we elicited the specific design requirements of the end-users. We then conducted 2 Exploratory Focus Groups to seek additional inputs for improvement and 2 Confirmatory Focus Groups to validate the proposed artifact and test its usability in the field. RESULTS Findings from thematic analysis of the need-assessment FG revealed a demand for sense making, simplification of app functionalities, maximized integration, and minimized feeling of external control. Participants involved in the later stages of the design refinement contributed to improve the design further by refining the app layout and adding aspects such as a chatbot function and a visual feedback on the number of hours the wearable device has been worn, to make sure the minimum is reached and observed data are actually registered. The end-users rated the app highly during the quantitative assessment, with an average MAUQ score of 5.32 (range 4.44-6.23) and 6.20 (5.72-6.88) out of seven in the two iterative usability testing cycles. CONCLUSIONS The results of the usability test indicated high and growing satisfaction with the app. The adoption of a thorough user-centered design process can maximize the likelihood of sustained retention of the POWER mHealth app and make it fit for data collection of relevant outcomes in the observational study. Findings from our work support the use of different types of focus groups in the design process of a mHealth app. Continuous use of this tool and the actual level of engagement will be properly evaluated during the on-going study.

No abstract