Conjoint analysis of social inequality indicators in diet and physical activity app (non-)users: Representative online surveys in Austria, Germany and Italy.

Background: Mobile interventions for health promotion (mHealth) are promising behaviour change tools. Yet they are infrequently used, and research suggests that use may be unevenly distributed in the population, potentially widening existing health inequalities. Objective: This study tested for individual and joint associations between socio-demographic characteristics and nutrition and physical activity app use. Methodology: Nationally representative samples for Austria, Germany and Italy were recruited with Results: Except for residency and migration status, all socio-demographic characteristics were associated with mHealth app (non-)use if analysed independently. A latent class analysis revealed four distinct classes of mHealth app (non-)users. 'Young and diverse citizens' (characterised by young age and lowest proportion of heterosexuals) and 'economically strong employees' (characterised by highest levels of education and income) were more likely to use mHealth apps compared to 'established retirees' (characterised by largest share of retired individuals) and 'low-income workers' (characterised by lowest levels of education and income). Conclusion: Age, education, income and employment are crucial inequality indicators for mHealth app use. These results confirm the existence of a digital health divide in Europe that urgently needs addressing to promote digital health for all. Trial registration: https://osf.io/s2wya (Austria and Germany), https://osf.io/tpu2m (Italy).