Inequalities in Exclusively Mobile Interventions Targeting Weight-Related Behaviors: Systematic Review of Observational Studies

Mobile health interventions are promising behavior change tools, but they might benefit deprived populations less due to disparities in intervention uptake, engagement, and effectiveness. Evidence so far mainly stems from clinical trials, which may suffer from selection bias. This systematic review investigated differences in uptake of, engagement with, and effectiveness of exclusively mobile interventions for diet, physical activity, and sedentary behavior in adults and real-life contexts. Five databases (CINAHL, EMBASE, PsycINFO, PubMed, and Web of Science) were searched from inception to November 2023. Records were independently screened by two authors. Observational studies including adults were considered if they reported on uptake, engagement, or effectiveness of an exclusively mobile intervention and examined outcomes by at least one inequality indicator included in the PROGRESS-Plus framework. Of the 9707 identified records, 87 publications reporting on 88 studies were included. Most studies reported on intervention uptake and examined multiple inequality indicators. Younger age and higher socioeconomic position were mostly associated with increased uptake, although these differences did not translate to engagement or effectiveness. Results for other inequality indicators were mixed, and some (e.g., migration and sexual orientation) were rarely studied. Evidence regarding social inequality remains mixed, although some barriers to uptake, such as access to the required technology and digital literacy, exist. Research urgently needs to address potential inequalities beyond age, gender/sex, and socioeconomic position to ensure that mobile interventions do not widen existing health inequalities.