Data Analysis
SPSS (version 26; IBM Corp) was used to analyze the data. Differences in the number of participants in the mHealth+I and mHealth groups using the mHealth app within T2 and T3 were analyzed using a chi-square test. To evaluate differences in outcome between those who continued to use the app within the period from 3 to 6 months and those who did not, the participants were further divided into the mHealth+I group with sustained app usage after T2 [mHealth+I(S)], the mHealth+I group without app usage after T2 [mHealth+I(N)], the mHealth group with sustained usage after T2 [mHealth(S)], the mHealth group without app usage after T2 [mHealth(N)], and the control group. The participants who have logged into the app at least twice per week and spend more than 5 minutes each time after T2 will be counted into the (S) group. The Generalized Estimating Equation was adopted to compare the between-group, within-group, and interaction effects between time and group for each outcome. It is worth mentioning that considering the samples in each subgroup may be small, factors associated with sustained use were not included in the analysis due to the potential of exaggerating the GEE estimates. Intention-to-treat was used as the primary analysis in this study. 