Adherence to 24-hour movement guidelines and health-related quality of life from childhood to late adolescence: a prospective cohort study of Australian youth.

BACKGROUND: Adherence to integrated 24-hour movement guidelines (moderate-to-vigorous physical activity, recreational screen time, and sleep) is low among young people but has been linked tolinked to better health-related quality of life (HRQoL). However, the evidence is largely cross-sectional and may not adequately capture factors that change over time. This study examined whether adherence across childhood and mid-adolescence is associated with HRQoL in late adolescence, whether adherence predicts HRQoL at subsequent wave, and whether these associations differ by sex. METHODS: Data from the Longitudinal Study of Australian Children (LSAC; Kindergarten cohort), Waves 2-7 (n = 4,463 at age 6-7 years, followed to 16-17 years) were analysed. Adherence to all three guideline components was derived from time-use diaries at each wave. HRQoL (physical, psychosocial and total; 0-100) was measured using the Pediatric Quality of Life Inventory (PedsQL). We used structural nested mean models fitted via g-estimation to estimate (i) the cumulative association per additional wave of adherence from ages 6-15 with HRQoL at ages 16-17, and (ii) lead-lag associations between adherence at wave t and HRQoL at wave t + 1, adjusting for baseline and time-varying covariates. Sex-stratified analyses were also conducted. RESULTS: Adherence declined from 24.5% at ages 6-7 to 7.2% at ages 14-15. Each additional wave of adherence was associated with higher total HRQoL at ages 16-17 (mean difference 0.81 PedsQL points; Bonferroni-adjusted 95% confidence interval (CI) 0.10 to 1.51). In lead-lag analyses, adherence predicted higher HRQoL at the subsequent wave for physical functioning (1.73; 0.90 to 2.53), psychosocial functioning (1.33; 0.58 to 2.08) and overall HRQoL (1.37; 0.68 to 2.06). In sex-stratified analyses, significant next-wave associations were observed for psychosocial functioning (1.10; 0.12 to 2.06) and overall HRQoL (1.22; 0.28 to 2.06) in boys, and for physical functioning (2.33; 1.02 to 3.56), psychosocial functioning (1.60; 0.63 to 2.64) and overall HRQoL (1.54; 0.57 to 2.53) in girls; in boys, each additional wave of adherence was also associated with higher overall HRQoL at ages 16-17 (1.15; 0.28 to 2.07). CONCLUSIONS: Given the low and declining prevalence of adherence, these findings suggest that the 24-h movement guidelines may be relevant to public health, health promotion, and preventive care efforts aimed at supporting HRQoL across childhood and adolescence.