Influence of Patient Characteristics and Psychological Needs on Diabetes Mobile App Usability in Adults With Type 1 or Type 2 Diabetes: Crossover Randomized Trial

Background More than 1100 diabetes mobile apps are available, but app usage by patients is low. App usability may be influenced by patient factors such as age, sex, and psychological needs. Objective Guided by Self-Determination Theory, the purposes of this study were to (1) assess the effect of patient characteristics on app usability, and (2) determine whether patient characteristics and psychological needs (competence, autonomy, and connectivity)—important for motivation in diabetes care—are associated with app usability. Methods Using a crossover randomized design, 92 adults with type 1 or 2 diabetes tested two Android apps (mySugr and OnTrack) for seven tasks including data entry, blood glucose (BG) reporting, and data sharing. We used multivariable linear regression models to examine associations between patient characteristics, psychological needs, user satisfaction, and user performance (task time, success, and accuracy). Results Participants had a mean age of 54 (range 19-74) years, and were predominantly white (62%, 57/92), female (59%, 54/92), with type 2 diabetes (70%, 64/92), and had education beyond high school (67%, 61/92). Participants rated an overall user satisfaction score of 62 (SD 18), which is considered marginally acceptable. The satisfaction mean score for each app was 55 (SD 18) for mySugr and 68 (SD 15) for OnTrack. The mean task completion time for all seven tasks was 7 minutes, with a mean task success of 82% and an accuracy rate of 68%. Higher user satisfaction was observed for patients with less education (P=.04) and those reporting more competence (P=.02), autonomy (P=.006), or connectivity with a health care provider (P=.03). User performance was associated with age, sex, education, diabetes duration, and autonomy. Older patients required more time (95% CI 1.1-3.2) and had less successful task completion (95% CI 3.5-14.3%). Men needed more time (P=.01) and more technical support than women (P=.04). High school education or less was associated with lower task success (P=.003). Diabetes duration of ≥10 years was associated with lower task accuracy (P=.02). Patients who desired greater autonomy and were interested in learning their patterns of BG and carbohydrates had greater task success (P=.049). Conclusions Diabetes app usability was associated with psychological needs that are important for motivation. To enhance patient motivation to use diabetes apps for self-management, clinicians should address competence, autonomy, and connectivity by teaching BG pattern recognition and lifestyle planning, customizing BG targets, and reviewing home-monitored data via email. App usability could be improved for older male users and those with less education and greater diabetes duration by tailoring app training and providing ongoing technical support.

INTRODUCTION 2a-i) Problem and the type of system/solution proof page 2 2a-ii) Scientific background, rationale: What is known about the (type of) system proof page 1 Does your paper address CONSORT subitem 2b? proof page 2 METHODS 3a) CONSORT: Description of trial design (such as parallel, factorial) including allocation ratio proof page 3 3b) CONSORT: Important changes to methods after trial commencement (such as eligibility criteria), with reasons no 3b-i) Bug fixes, Downtimes, Content Changes 4a) CONSORT: Eligibility criteria for participants proof page 3 4a-i) Computer / Internet literacy We verified mobile phone use proficiency by screening for app use and did not include typical mobile phone usage for calls, texting, emailing, or taking pictures. 4a-ii) Open vs. closed, web-based vs. face-to-face assessments: Procedures section 4a-iii) Information giving during recruitment proof page 3 4b) CONSORT: Settings and locations where the data were collected 7. Individual study sessions were held in a private room. 4b-i) Report if outcomes were (self-)assessed through online questionnaires proof page 3 4b-ii) Report how institutional affiliations are displayed Proof page 3 5) CONSORT: Describe the interventions for each group with sufficient details to allow replication, including how and when they were actually administered 5-i) Mention names, credential, affiliations of the developers, sponsors, and owners Proof page 3 5-ii) Describe the history/development process proof page 4

5-iii) Revisions and updating
The same 2017 version of both apps were used during the study period 5-iv) Quality assurance methods proof page 3 5-v) Ensure replicability by publishing the source code, and/or providing screenshots/screen-capture video, and/or providing flowcharts of the algorithms used proof page 3 5-vi) Digital preservation OnTrack and mySugr are publicly available in the app store 5-vii) Access proof page 3 5-viii) Mode of delivery, features/functionalities/components of the intervention and comparator, and the theoretical framework Theoretical Framework section proof page 2 5-ix) Describe use parameters proof page 3 -procedure 5-x) Clarify the level of human involvement proof page 3 -procedure 5-xi) Report any prompts/reminders used proof page 4 -

5-xii) Describe any co-interventions (incl. training/support)
Proof page 3 and 4 6a) CONSORT: Completely defined pre-specified primary and secondary outcome measures, including how and when they were assessed Measurements section in the paper Proof page 4 6a-i) Online questionnaires: describe if they were validated for online use and apply CHERRIES items to describe how the questionnaires were designed/deployed not applicable 6a-ii) Describe whether and how "use" (including intensity of use/dosage) was defined/measured/monitored Proof page 3 6a-iii) Describe whether, how, and when qualitative feedback from participants was obtained Proof page 3 6b) CONSORT: Any changes to trial outcomes after the trial commenced, with reasons 7. Individual study sessions were held in a private room. 7a) CONSORT: How sample size was determined 7a-i) Describe whether and how expected attrition was taken into account when calculating the sample size Proof page 4 7b) CONSORT: When applicable, explanation of any interim analyses and stopping guidelines Measurements section in the paper Proof page 4 8a) CONSORT: Method used to generate the random allocation sequence Proof page 3 8b) CONSORT: Type of randomisation; details of any restriction (such as blocking and block size) Proof page 3 9) CONSORT: Mechanism used to implement the random allocation sequence (such as sequentially numbered containers), describing any steps taken to conceal the sequence until interventions were assigned Proof page 3 10) CONSORT: Who generated the random allocation sequence, who enrolled participants, and who assigned participants to interventions Proof page 3 11a) CONSORT: Blinding -If done, who was blinded after assignment to interventions (for example, participants, care providers, those assessing outcomes) and how 11a-i) Specify who was blinded, and who wasn't Proof page 3 11a-ii) Discuss e.g., whether participants knew which intervention was the "intervention of interest" and which one was the "comparator" Proof page 3 11b) CONSORT: If relevant, description of the similarity of interventions Not applicable 12a) CONSORT: Statistical methods used to compare groups for primary and secondary outcomes Proof page 4 12a-i) Imputation techniques to deal with attrition / missing values The only missing data was an HbA1c level from one participant.

12b) CONSORT: Methods for additional analyses, such as subgroup analyses and adjusted analyses
Proof page 4 RESULTS 13a) CONSORT: For each group, the numbers of participants who were randomly assigned, received intended treatment, and were analysed for the primary outcome

Proof page 4 13b) CONSORT: For each group, losses and exclusions after randomisation, together with reasons
There were no losses. The only missing data was an HbA1c level from one participant. 13b-i) Attrition diagram not applicable, we did not have attrition 14a) CONSORT: Dates defining the periods of recruitment and follow-up Proof page 3 and 4 14a-i) Indicate if critical "secular events" fell into the study period not applicable 14b) CONSORT: Why the trial ended or was stopped (early) The trial did not ended or stop early.

15) CONSORT: A table showing baseline demographic and clinical characteristics for each group
Proof page 4 and 5 15-i) Report demographics associated with digital divide issues In Table 1. Device brand, n (%) and Mobile phone comfort level, n (%)

16a) CONSORT: For each group, number of participants (denominator) included in each analysis and whether the analysis was by original assigned groups 16-i) Report multiple "denominators" and provide definitions
Proof page 1

16-ii) Primary analysis should be intent-to-treat
All participants were analyzed. 17a) CONSORT: For each primary and secondary outcome, results for each group, and the estimated effect size and its precision (such as 95% confidence interval) Proof page 3-6 17a-i) Presentation of process outcomes such as metrics of use and intensity of use This was not applicable in this study. 17b) CONSORT: For binary outcomes, presentation of both absolute and relative effect sizes is recommended not applicable. We did not have binary outcomes 18) CONSORT: Results of any other analyses performed, including subgroup analyses and adjusted analyses, distinguishing pre-specified from exploratory Proof page 6 18-i) Subgroup analysis of comparing only users Proof page 6 19) CONSORT: All important harms or unintended effects in each group Proof page 9, Fatigue with the 2-hour testing session ..

19-i) Include privacy breaches, technical problems
Proof page 3 19-ii) Include qualitative feedback from participants or observations from staff/researchers Proof page 9 DISCUSSION 20) CONSORT: Trial limitations, addressing sources of potential bias, imprecision, multiplicity of analyses

20-i) Typical limitations in ehealth trials
Proof page 9 21) CONSORT: Generalisability (external validity, applicability) of the trial findings 21-i) Generalizability to other populations Proof page 9 21-ii) Discuss if there were elements in the RCT that would be different in a routine application setting Proof page 9 22) CONSORT: Interpretation consistent with results, balancing benefits and harms, and considering other relevant evidence 22-i) Restate study questions and summarize the answers suggested by the data, starting with primary outcomes and process outcomes (use) Discussion sectionProof page 8 and 9 22-ii) Highlight unanswered new questions, suggest future research Proof page 9 Other information 23) CONSORT: Registration number and name of trial registry While this study uses a randomized controlled design (i.e., crossover design), participants did not receive a health-related intervention and does not involve a health-related outcome. Rather, the research is a "simulated experiment" to assess app usability and user satisfaction with using apps that contained fake/simulated data. Therefore, this study is not a clinical trial and is exempt from clinical trial registration.

24) CONSORT: Where the full trial protocol can be accessed, if available
Our study used a protocol. It is available upon request. 25) CONSORT: Sources of funding and other support (such as supply of drugs), role of funders Acknowledgement Proof page 9 X26-i) Comment on ethics committee approval Proof page 3 x26-ii) Outline informed consent procedures Proof page 3 X26-iii) Safety and security procedures Proof page 3 X27-i) State the relation of the study team towards the system being evaluated Proof page 9