ALSPAC AND CROSS-COHORT STUDIES Causal Effects of Breastfeeding on Child Health Outcomes - PowerPoint PPT Presentation

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ALSPAC AND CROSS-COHORT STUDIES Causal Effects of Breastfeeding on Child Health Outcomes

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Title: ALSPAC and Cross-Cohort Studies: Causal Effects of Breastfeeding on Child Health Outcomes Subject: Community Medicine Author: Marie-Jo Brion – PowerPoint PPT presentation

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Title: ALSPAC AND CROSS-COHORT STUDIES Causal Effects of Breastfeeding on Child Health Outcomes


1
ALSPAC AND CROSS-COHORT STUDIESCausal Effects
of Breastfeeding onChild Health Outcomes
  • Marie-Jo Brion
  • Sir Henry Wellcome Postdoctoral Fellow
  • MRC Centre for Causal Analyses in Translational
    Epidemiology
  • School of Social and Community Medicine
  • University of Bristol

2
Cause and Effect in Observational
StudiesGetting the Right Answer
  • Examples where observational studies and RCTs
    fail to arrive at the same answer
  • Protective effects on CVD from observational
    studies
  • Beta carotene
  • Vitamin E supplements
  • Vitamin C supplements
  • Hormone replacement therapy
  • Large RCTs showed no protective effect
  • Likely explanation confounding
  • in particular, confounding by socioeconomic
    position
  • NEED BETTER CAUSAL APPROACHES

3
What are the causal effects of breastfeedingon
IQ, obesity and blood pressure?
Evidence from comparing
high-incomewith middle-income cohorts
  • Marie-Jo Brion, Debbie Lawlor, Alicia
    Matijasevich, Bernardo Horta, Luciana Anselmi,
    Ana Maria B Menezes, Cesar Victora, George Davey
    Smith
  • Brion et al (2011) IJE 40(3) 670

4
Objectives
  • Explore novel approach for improving causal
    inference in observational studies
  • Comparing associations from HIC to LMIC cohorts
    where associations of confounders with health
    outcomes are likely to differ between cohorts
  • Assessing causal effects of breastfeeding on
    child BP, BMI and IQ

5
less smoking
healthy diet
better living conditions
physical activity
higher socioeconomic position
healthier families
education
Causal effects ??
6
Methods
  • ALSPAC, UK (N5000) and Pelotas 1993, Brazil
    (N1000)
  • Meta-analyses of 5 LMIC (COHORTS consortium
    N11,000)
  • Fall et al., IJE 2011
  • Randomised trial of breastfeeding promotion
    (PROBIT Belarus trial)
  • Kramer et al., Arch Gen Psychiatry 2008
    Kramer et al., AJCN 2007

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10
Analyses
  • Associations of indicators of SEP with
    breastfeeding
  • Maternal education
  • paternal education
  • family income
  • occupational social class
  • Associations of breastfeeding duration with child
    outcomes

11
Prevalence () Prevalence ()
Breastfeeding duration Pelotas ALSPAC

0 to lt1 month 15.6 36.8
1 to lt 3 months 25.4 15.6
3 to lt 6 months 23.6 13.7
6 months or more 35.3 33.9

Ever breastfed 96.8 84.3
Exclusive breastfeeding at 2 months 65.7 38.3

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13
Relative/Slope Index of Inequality
  • Logistic regression SEP indicator with binary
    outcomes
  • Odds of outcome in highest SEP level (1) versus
    the lowest (0)
  • Linear regression SEP indicator with continuous
    outcomes
  • Difference in outcome between highest SEP level
    (1) and the lowest (0)

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15
BMI
16
less smoking
Discordant ALSPAC-Pelotas
healthy diet
better living conditions
physical activity
higher socioeconomic position
healthier families
education
Causal effects ??
17
Mean difference in outcome by breastfeeding category Mean difference in outcome by breastfeeding category Mean difference in outcome by breastfeeding category Mean difference in outcome by breastfeeding category

Outcome ALSPAC ß (95 CI) P trend Pelotas ß (95 CI) P trend

SBP, -0.35 (-0.55, -0.14) 0.001 -0.13 (-0.83, 0.57) 0.7
(mmHg)


DBP -0.16 (-0.31, -0.01) 0.04 0.05 (-0.50, 0.60) 0.9
(mmHg)


BMI -0.16 (-0.22, -0.09) lt0.001 0.14 (-0.07, 0.36) 0.2
(kg/m2)


IQ 0.97 (0.62, 1.32) lt0.001 1.97 (0.88, 3.05) lt0.001

Breastfeeding categories 0 to lt1m 1 to lt3m 3
to lt6m 6m or more Fully adjusted models
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Comparison Method Comparison Method Comparison Method Comparison Method Comparison Method Comparison Method Validation Validation
ALSPAC Strong socioeconomic patterning in breastfeeding ALSPAC Strong socioeconomic patterning in breastfeeding ALSPAC Strong socioeconomic patterning in breastfeeding Pelotas Weak socioeconomic patterning in breastfeeding Pelotas Weak socioeconomic patterning in breastfeeding Pelotas Weak socioeconomic patterning in breastfeeding Belarus Randomised Trial Belarus Randomised Trial
Association with any breastfeeding (per category) Association with any breastfeeding (per category) Association with any breastfeeding (per category) Association with any breastfeeding (per category) Association with any breastfeeding (per category) Association with any breastfeeding (per category) Effect of breastfeeding intervention Effect of breastfeeding intervention
Outcome ß 95 CI P ß 95 CI P Difference in outcome 95 CI
SBP, mmHg -0.35 -0.55, -0.14 0.001 -0.13 -0.83, 0.57 0.7 0.2 -2.9, 3.3
DBP, mmHg -0.16 -0.31, -0.01 0.04 0.05 -0.50, 0.60 0.9 0.2 -1.8, 2.2
BMI, kg/m2 -0.16 -0.22, -0.09 lt0.001 0.14 -0.07, 0.36 0.2 0.1 -0.2, 0.3
IQ 0.97 0.62, 1.32 lt0.001 1.97 0.88, 3.05 lt0.001 5.9 -1.0, 12.8
Adjusted for all indicators of maternal
education, paternal education, family income,
occupational social class
21
Using the totality of the evidence
22
Integrating cross-cohorts and additional causal
approaches
  • Maternal prenatal smoking and child aggression
  • Exploring intrauterine effects in UK, Australian
    and
  • Brazilian cohorts
  • Marie-Jo Brion, Monique Robinson, Alicia
    Matijasevich, Colin Steer, Luciana Anselmi, Ana
    Menezes, Craig Pennell, Lyle Palmer, Cesar
    Victora, George Davey Smith, Debbie Lawlor
  • Brion et al. (under review)

23
Multi-method approach for assessing intrauterine
mechanisms
24
Multivariable Regression
25
Cross-cohort confounders
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Maternal-Paternal Comparisons
28
Prenatal-Postnatal Comparisons
29
Single Method Approach
  • Conventional multivariable regression
  • independent associations of maternal smoking and
    child aggression
  • intrauterine effects as a possible explanation

30
Totality of Evidence From Multiple Methods
  • Total evidence for intrauterine effects is weak
  • Not consistent with SEP being primary / sole
    determinant
  • Confounding by other familial factors

31
ALSPAC and Cross-Cohort Studies
  • ALSPAC integrated with additional cohorts to
    explore cross-cohort approach for improving
    causal inference based on conventional method
    alone
  • Value of integrating multiple methods for
    assessing causal mechanisms to arrive at
    conclusions based on totality of evidence
  • Breastfeeding and child BMI, BP and IQ
  • Evidence supporting causal effects breastfeeding
    duration on greater IQ
  • Maternal prenatal smoking and child aggression
  • Weak evidence for intrauterine mechanisms
  • Not consistent with SEP being the main
    explanation for the association
  • Other family-level confounders are likely

32
Acknowledgements
  • CAiTE, University of Bristol
  • Debbie Lawlor
  • George Davey Smith
  • Colin Steer
  • Federal University of Pelotas
  • Cesar Victora
  • Alicia Matijasevich
  • Bernardo Horta
  • Other Co-authors
  • Monique Robinson, Craig Pennell, Lyle Palmer
  • Luciana Anselmi, Ana Menezes
  • Wellcome Trust UK
  • Henry Wellcome Postdoctoral Fellowship
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