Smartphone use health outcomes in children and adolescents: A systematic review of behavioral, developmental, and environmental risk pathways

Table 2 Prevalence and patterns of smartphone use in children and adolescents before and during the coronavirus disease 2019 pandemic

Ref.	Country	Study design	Sample size (n)	Age range	Period	Prevalence/usage findings	Key observations	Key strengths	Potential bias/limitations	Overall risk category
Kabali et al[13], 2015	United States	Cross-sectional (community-based)	350	6 months to 4 years	Pre-COVID (2014)	96.6% had used a mobile device	Most initiated < 1 year; approximately 75% owned device by age 4; daily use common by age 2	Clear inclusion criteria; utilized adapted validated survey from Common Sense Media	Specific to urban, low-income, minority population; limited generalizability to high-SES groups	Low
Shah and Phadke[14], 2023	India	Cross-sectional (hospital-based)	90	6 months to 4 years	Pre-COVID	73.3% prevalence of use	19% (3-4 years) ≥ 3 hours/day; parental reluctance high despite use	Validated questionnaire used; clear ethical and consent protocols	Small sample size (n = 90) from a single tertiary hospital	Moderate
Kopecký et al[9], 2021	Czech Republic	Cross-sectional (school survey)	27177	7-17 years	Pre-COVID (2014-2018)	Near-universal exposure1	High engagement in social media, YouTube, gaming; school policy influenced usage	Exceptionally large sample size (n = 27177); objective comparison of school policies	Reliance on self-reported behaviors rather than objective logs	Low
Kayiran et al[15], 2010	Turkey	Cross-sectional	724	6 months to 15 years	Pre-COVID	Not mobile-specific	Increasing device access and bedroom ownership with age	Large sample size (n = 724) for the specific SES demographic	Convenience sampling in a private hospital; potential for social desirability bias in parent reporting	Moderate
Lee et al[17], 2025	South Korea	National survey secondary analysis	54948	Middle and high school	During COVID	25.5% PSU; mean use 2828 minutes (weekday), 393.4 minutes (weekend)	Higher PSU among females and high school students; alcohol and smoking increased risk	Huge national dataset (n = 54948); complex sample statistical weighting for accuracy	Secondary data analysis limits control over initial measurement tools; self-reported	Low
Chun et al[18], 2023	South Korea	Cross-sectional	360	15-18 years	During COVID	Increased addiction among those with increased usage time	Associated with depressive symptoms, low self-control, cyberbullying; socioeconomic factors relevant	Uses a social-ecological model to categorize factors (individual, family, school)	Sample restricted to Korean adolescents aged 15-18; limited age range	Low
Serra et al[19], 2021	Italy	Cohort (self-report, pre-post comparison)	184	6-18 years	During COVID	Significant increase in frequency and duration of use vs pre-epidemic	Increased overuse/addiction; sleep, ocular, and musculoskeletal complaints	Evaluates specific health outcomes (ocular, musculoskeletal) alongside addiction	Anonymous questionnaire limits follow-up; significant gender imbalance in respondents (more females)	Low
Ferrara et al[20], 2023	Italy	Pre-post survey	130	6-18 years	During COVID	Significant increase in screen time (P < 0.02); higher addiction index (P < 0.001)	Increased early-morning headaches; reduced physical activity	Direct pre- vs post-lockdown comparison	Retrospective recall bias (asking about pre-lockdown habits during lockdown)	Moderate

¹Exact prevalence not extractable due to variation in outcome definitions. Risk of Bias tool: Joanna Briggs Institute (analytical).

PSU: Problematic smartphone use; COVID: Coronavirus disease; SES: Socioeconomic status.