Age of first digital device use and screen media use at age 15: A cross-sectional analysis of 384,591 participants from 55 countries

Objectives: We investigated the associations between age of first digital device use and screen media use at age 15. Study design and methods: Utilizing cross-sectional data from the 2018 Program for International Student Assessment, we analyzed responses from 384,591 fifteen-year-olds (50 % girls) from 55 countries on their age of first device use and current frequency of 12 screen behaviours. Behaviors were categorized as social, gaming, recreational, educational/practical (grouped into regular [every day; almost every day] and non-regular users [once or twice a week; once or twice a month; never or hardly ever]. Generalized linear regression, adjusted for highest level of schooling of mother/father and with student sampling and replicate weights to account for the sampling design was used to estimate prevalence ratios (PR) for regular use of each screen activity per additional year of age when first using devices. Results: Higher age of first device use was associated with lower prevalence of being a regular user for nine screen behaviours at age 15, with some sex differences. The strongest association was found for using email’ (PR per increasing year of first device use for total sample: 0.956 [95%CI 0.935; 0.977]; boys: 0.956 [95%CI 0.928; 0.986]) and playing collaborative online games (girls: 0.947 [95%CI 0.905; 0.991]). Later first use of devices was associated with decreased prevalence of regular use for social purposes at age 15. Conclusion: The later children start using digital devices, the less likely they are to be regular users at 15 years, especially social use. Delaying children's introduction to digital devices may decrease future use.