Background To investigate whether time spent in educational activities at 2–3 years and developmental outcomes at school entry differ among children from different socioeconomic backgrounds.
Methods Participants were from the Longitudinal Study of Australian Children (n=4253). Time spent in educational activities was collected using 24-hour time-use diaries. Income was measured using parent self-report. Receptive vocabulary was assessed using the Peabody Picture Vocabulary Test, and problem behaviours were measured by the Strengths and Difficulties Questionnaire. Marginal structural models were used to test whether the effects of educational activities on outcomes differed by income.
Results Children exposed to both <30 min/day in educational activities and being in a low-income household were at greater risk of poorer outcomes at school entry than the simple sum of their independent effects. Compared with children who spent ≥30 min/day in educational activities from high-income households, children who experienced <30 min/day in educational activities from low-income households had a 2.30 (95% CI 1.88 to 2.80) higher risk of having a receptive vocabulary score in the lowest quartile at school entry. The Relative Excess Risk due to Interaction of 0.15 (95% CI −0.38 to 0.67) was greater than 0, indicating a super-additive effect measure modification by income. These patterns were similar for behavioural outcomes.
Conclusions Our findings suggest that if there was an intervention of sufficient dose to increase the amount of time spent in educational activities to at least 30 min/day for children in the lower-income group, the risk of children having sub-optimal receptive vocabulary would be reduced by 45% and the risk of teacher-reported conduct and hyperactivity problems reduced by 67% and 70%, respectively.
- CHILD HEALTH
- Cohort studies
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Contributors AG conceived the idea for the study, designed the study, contributed to the statistical analysis plan, drafted the initial manuscript and approved the final manuscript as submitted. DGH contributed to the study design and statistical analysis plan, conducted the statistical analysis, reviewed and revised the manuscript, and approved the final manuscript as submitted. MNM and JWL contributed to the study design and statistical analysis plan, reviewed and revised the manuscript, and approved the final manuscript as submitted.
Funding This work was supported by a Channel 7 Children’s Research Foundation grant (grant number 171424) and a National Health and Medical Research Council Centre of Research Excellence (grant number 1099422). AG and DGH are supported by funds from the Research Centre of Excellence grant. The researchers are independent of the funding bodies.
Competing interests None declared.
Patient consent for publication Not required.
Data sharing statement Data may be obtained from a third party and are not publicly available.
Provenance and peer review Not commissioned; externally peer reviewed.
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