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Pathways to inequalities in child mental health: a causal mediation analysis of evidence from two national birth cohorts
Meeting Abstracts
Pathways to inequalities in child mental health: a causal mediation analysis of evidence from two national birth cohorts Eric T C Lai, Theis Lange, Viviane S Straatmann, Anne-Marie Nybo Andersen, Katrine Strandberg-Larsen, David Taylor-Robinson
Abstract
Background Pathways linking socioeconomic circumstances to child mental health problems are poorly understood. We used two national birth cohorts to assess how social inequalities in child mental health problems were mediated by perinatal factors, childhood illness, and maternal mental health. Methods We applied causal mediation analysis to longitudinal data from the Danish National Birth Cohort (DNBC; n=26251) and the UK Millennium Cohort Study (MCS; n=13112). The exposure was maternal education at birth, a measure of childhood socioeconomic circumstances. The outcome, child mental health problems, was measured by the Strength and Difficulty Questionnaire at age 11 years with country-specific cut-offs. We estimated the natural direct and indirect effect and total effect of socioeconomic circumstances on mental health problems, calculating the relative risk across the socio-economic hierarchy (relative index of inequality, RII). Using natural effect models, we calculated the proportion mediated (PM) via three blocks of mediators sequentially whilst adjusting for confounding. Three potentially mediating blocks were perinatal factors (smoking or alcohol use during pregnancy, low birthweight, and gestational age), childhood illness, and maternal mental health, measured up to child age 7 years. Findings At age 11 years, 3·7% (n=1375) and 9% (n=1130) of children had mental health problems in Denmark (DBNC: mean age 11·4 years [SD 0·6]; 50% boys) and the UK (MCS: 10·7 years [0·5]; 51% boys), respectively. Lower socioeconomic circumstances were associated with mental health problems for both cohorts (DNBC: RII=5·9, 95% confidence interval 4·6–7·6]; MCS: RII=4·3, 95% CI 3·3–5·5). In DNBC, perinatal factors mediated 14·6% (95% CI 9.7–19.4) of social inequalities in MHP. Including childhood illness in the model barely increased PM, and addition of maternal mental health increased PM to 15·5% (95% CI 9·8–21·2). In MCS, perinatal factors mediated 10·2% of the association (95% CI 4·5–15·9). Addition of childhood illness barely increased PM, but addition of maternal mental health tripled PM to 32·2% (25·4–39·1). Interpretation Our findings suggest that UK children are more at risk of mental health problems than are Danish children. Social inequalities in such problems at age 11 year are partly explained by perinatal factors in the UK and Denmark. Maternal mental health might be an important mediator of social inequalities in child mental health problems in the UK, but not in Denmark.
Published Online November 29, 2019 Department of Public Health and Policy, University of Liverpool, Liverpool, UK (E T C Lai PhD, V S Straatmann PhD, Prof D Taylor-Robinson PhD); Section of Epidemiology (ETC Lai, Prof A-M Nybo Andersen PhD, K Strandberg-Larsen PhD, Prof D Taylor-Robinson) and Section of Biostatistics (T Lange PhD), Department of Public Health, University of Copenhagen, Copenhagen, Denmark; Centre for Statistical Science, Peking University, Beijing, China (T Lange); and Aging Research Center, Karolinska Institute and Stockholm University, Stockholm, Sweden (V S Straatmann PhD) Correspondence to: Dr Eric T C Lai, Department of Public Health and Policy, Institute of Population Health Sciences, University of Liverpool, Liverpool L69 3GL, UK [email protected]
Funding ETCL and DTR are funded by the MRC on a Clinician Scientist Fellowship (MR/P008577/1). TL, KS-L and A-MNA were funded by University of Copenhagen. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Contributors ETCL did the statistical analysis and wrote the abstract with input from DT-R. ETCL, DT-R, and KS-L conceptualised the study. VSS and A-MNA helped with data interpretation. TL helped to design the statistical analysis. All authors critically reviewed and approved the final version of the abstract for publication. Declaration of interests We declare no competing interests.
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Pathways to inequalities in child mental health: a causal mediation analysis of evidence from two national birth cohorts Eric T C Lai, Theis Lange, Viviane S Straatmann, Anne-Marie Nybo Andersen, Katrine Strandberg-Larsen, David Taylor-Robinson
Abstract
Background Pathways linking socioeconomic circumstances to child mental health problems are poorly understood. We used two national birth cohorts to assess how social inequalities in child mental health problems were mediated by perinatal factors, childhood illness, and maternal mental health. Methods We applied causal mediation analysis to longitudinal data from the Danish National Birth Cohort (DNBC; n=26251) and the UK Millennium Cohort Study (MCS; n=13112). The exposure was maternal education at birth, a measure of childhood socioeconomic circumstances. The outcome, child mental health problems, was measured by the Strength and Difficulty Questionnaire at age 11 years with country-specific cut-offs. We estimated the natural direct and indirect effect and total effect of socioeconomic circumstances on mental health problems, calculating the relative risk across the socio-economic hierarchy (relative index of inequality, RII). Using natural effect models, we calculated the proportion mediated (PM) via three blocks of mediators sequentially whilst adjusting for confounding. Three potentially mediating blocks were perinatal factors (smoking or alcohol use during pregnancy, low birthweight, and gestational age), childhood illness, and maternal mental health, measured up to child age 7 years. Findings At age 11 years, 3·7% (n=1375) and 9% (n=1130) of children had mental health problems in Denmark (DBNC: mean age 11·4 years [SD 0·6]; 50% boys) and the UK (MCS: 10·7 years [0·5]; 51% boys), respectively. Lower socioeconomic circumstances were associated with mental health problems for both cohorts (DNBC: RII=5·9, 95% confidence interval 4·6–7·6]; MCS: RII=4·3, 95% CI 3·3–5·5). In DNBC, perinatal factors mediated 14·6% (95% CI 9.7–19.4) of social inequalities in MHP. Including childhood illness in the model barely increased PM, and addition of maternal mental health increased PM to 15·5% (95% CI 9·8–21·2). In MCS, perinatal factors mediated 10·2% of the association (95% CI 4·5–15·9). Addition of childhood illness barely increased PM, but addition of maternal mental health tripled PM to 32·2% (25·4–39·1). Interpretation Our findings suggest that UK children are more at risk of mental health problems than are Danish children. Social inequalities in such problems at age 11 year are partly explained by perinatal factors in the UK and Denmark. Maternal mental health might be an important mediator of social inequalities in child mental health problems in the UK, but not in Denmark.
Published Online November 29, 2019 Department of Public Health and Policy, University of Liverpool, Liverpool, UK (E T C Lai PhD, V S Straatmann PhD, Prof D Taylor-Robinson PhD); Section of Epidemiology (ETC Lai, Prof A-M Nybo Andersen PhD, K Strandberg-Larsen PhD, Prof D Taylor-Robinson) and Section of Biostatistics (T Lange PhD), Department of Public Health, University of Copenhagen, Copenhagen, Denmark; Centre for Statistical Science, Peking University, Beijing, China (T Lange); and Aging Research Center, Karolinska Institute and Stockholm University, Stockholm, Sweden (V S Straatmann PhD) Correspondence to: Dr Eric T C Lai, Department of Public Health and Policy, Institute of Population Health Sciences, University of Liverpool, Liverpool L69 3GL, UK [email protected]
Funding ETCL and DTR are funded by the MRC on a Clinician Scientist Fellowship (MR/P008577/1). TL, KS-L and A-MNA were funded by University of Copenhagen. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Contributors ETCL did the statistical analysis and wrote the abstract with input from DT-R. ETCL, DT-R, and KS-L conceptualised the study. VSS and A-MNA helped with data interpretation. TL helped to design the statistical analysis. All authors critically reviewed and approved the final version of the abstract for publication. Declaration of interests We declare no competing interests.
www.thelancet.com
3