JMIR Publications

ABSTRACT

Background:

Digital interventions appear an easily scalable approach to promote healthy lifestyles, but the evidence of their large-scale effects and the equity of their effects remains limited—particularly for interventions that focus on habit formation.

Objective:

This explorative study examined the usage effects, effect modifiers, and user experiences of a web-based lifestyle app intended as a stand-alone support for a self-directed formation of healthy habits.

Methods:

A possibility to use the app for 3 months was offered to a sub-sample of Healthy Finland survey participants aged 20-74 years via SMS text message or letter. The app provided personalized behavioral suggestions that translated evidence-based guidelines into simple, repeatable actions. Users could browse and select the actions and report and monitor their performances. A quasi-experimental pre-post effect assessment built on continuous app log data; questionnaires collected with the app at baseline, 45, and 90 days; and data collected within the Healthy Finland survey prior to the uptake of the app. Linear mixed-effects models were used to explore a) the associations between app usage and changes in self-reported diet quality (Healthy Diet Index, HDI), physical activity (MET-hours/week), and BMI, and b) the modification of these associations by baseline characteristics related to sociodemographics, health, lifestyle, and e-service use. App usage measures comprised the percentage of use days and the number of reported performances (total, diet-, physical activity-, and BMI-related). User experiences were collected with a questionnaire at the end of the study.

Results:

Of 6975 invitees, 1282 (18.4%) accepted the invitation and 382 (5.5%; 69% women; mean age 51, SD 15) completed the data collection required for the assessment. Over 90 days, the median percentage of use days was 5.9% (IQR 3.3%-11%) and the total number of reported performances 22 (IQR 3-68.5). A higher percentage of use days (by 10 percentage points) was associated with a 3.09 (95% CI 0.79-5.39) MET-hours/week greater increase in physical activity, and a 1-unit higher logarithmic number of reported performances with a 0.51 (95% CI 0.07-0.95) HDI-point greater improvement in diet quality. Other associations between app usage and outcomes were non-significant. Greater physical activity and more positive attitude to e-services at baseline appeared to enhance the effect of app usage on physical activity (P values<.05). The app received a median acceptability rating of 2.9 (IQR 2.4-3.3, scale: 1-4), a median overall score of 7 (IQR 5-8, scale: 0-10), and a net promoter score of –48.

Conclusions:

An inexpensive, low-intensity digital support for a self-directed adoption of healthy habits could foster beneficial lifestyle change, but effects require user engagement and may depend on the individual. The findings warrant confirmation in more robust study designs and call for further research for identifying those most likely to benefit from such digital support.