+ early intervention and child health: evidence from a dublin based trial orla doyle a,b, nick...
TRANSCRIPT
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Early Intervention and Child Health: Evidence from a Dublin Based Trial Orla Doylea,b, Nick Fitzpatrickb, Judy Lovettc, Caroline Rawdond aUCD School of EconomicsbUCD Geary Institute for Public Policy
Irish Economic Association Annual Conference, 7th May 2015
+Background
Steep socio-economic gradient in health that emerges early in life (Case et al, 2002)
Poor health during childhood associated with adverse educational and labour market outcomes (Case et al., 2005; Currie and Hyson, 1999)
Identifying the causal pathways through which SES is related to child health is limited by endogeneity
+This Study
We utilize a randomized controlled trial, which experimentally modifies the parenting and home environment of disadvantaged families, to investigate a mechanism for ameliorating poor health
Early intervention may be effective from a biological and economic perspective
Home visiting programs (HVPs) target disadvantaged families from pregnancy onwards
Systematic reviews of HVPs report mixed findings on child health Avellar & Supplee (2013): 5 of 12 HVPs identify significant treatment effects Peacock et al. (2013): 2 of 7 HVPs identify significant treatment effects
But none account for small sample size, differential attrition or multiple hypothesis testing
+ Preparing for Life programme One of first & longest running Irish experimental interventions
Aim: Improve child school readiness by assisting parents from pregnancy-age 5
+ Treatment
1. Home-visiting Mentoring Programme
Fortnightly home-visits from a trained mentor from pre-birth to age 5
Mentors role: act as advisors to the participating families & support and educate parents about child development & parenting
Home visits structured around “Tip Sheets” - handouts presenting best-practice information relating to child development
2. Triple P Parenting Programme (Sanders et al., 2003) Promotes healthy parenting practices and positive parent-child
attachment
Group Triple P: 5 two-hour group discussion sessions and 3 phone calls
Offered when their children are between 2 and 3 years old
+ Recruitment & Randomisation
Eligibility Criteria: Cohort of pregnant women residing in catchment area between Jan 2008-
August 2010
Recruitment: Maternity hospital & within the local community (b/w 12-26 weeks) Population-based recruitment rate was 52%
Randomisation: Unconditional probability randomisation strategy
115 allocated to Treatment group 118 allocated to Control group
+ Data & Methodology
Data Baseline data: No statistical differences between treatment and control
groups on 114/126 baseline measures (90.5%)
Outcome data: Maternal reports of child health in previous 6/12 months assessed at 6, 12, 18, 24, and 36 months Child general health Number of health problems which required medical attention Incidences of hospitalization Incidences of accidents which required medical attention Incidences of asthma/wheezing which required medical attention Incidences of chest infections which required medical attention Received necessary immunizations
Methods Permutation based hypothesis testing (Heckman et al. 2010): small sample
inference Stepdown procedure (Romano & Wolf, 2005): multiple hypothesis testing Inverse Probability Weighting: differential attrition/missing data
7
+ Attrition
Allocated to Intervention (n = 115)
Allocated to Control (n = 118)
Randomized (n = 233)
Assessed at baseline (n = 104)
Assessed at baseline (n = 101)
Assessed at 24-months (n = 81)
Assessed at 18-months (n = 74)
Assessed at 6-months (n = 83)
Assessed at 6-months (n = 90)
Assessed at 12-months (n = 82)
Assessed at 12-months (n = 83)
Assessed at 18-months (n = 80)
Assessed at 36-months (n = 74)
Assessed at 36-months (n = 76)
Assessed at 24-months (n = 84)
+ Results: IPW-adjusted impact of treatment on Child Health (1)
N (intervention
/control)
Mintervention (SD) Mcontrol (SD) IPW chi-squared/t-test
pa
IPW Permutation Test
pb
IPW Stepdown Permutation Test
pb
Rated Good Health
6 months 173 (83/90) 0.92 (0.27) 0.94 (0.23) 0.580 0.591 0.932
12 months 165 (82/83) 0.94 (0.24) 0.93 (0.26) 0.833 0.841 0.97318 months 154 (80/74) 0.92 (0.27) 0.87 (0.34) 0.322 0.302 0.73124 months 165 (81/84) 0.95 (0.23) 0.84 (0.37) 0.054* 0.037** 0.12436 months 150 (74/76) 0.88 (0.33) 0.89 (0.32) 0.908 0.910 0.910
Number of Health Problems
6 months 173 (83/90) 1.38 (1.73) 1.24 (1.02) 0.414 0.605 0.96312 months 164 (81/83) 1.37 (1.49) 1.39 (1.12) 0.712 0.926 0.99518 months 154 (80/74) 1.42 (1.38) 1.31 (1.24) 0.664 0.651 0.95324 months 165 (81/84) 1.26 (1.31) 1.71 (1.55) 0.257 0.089* 0.27936 months 150 (74/76) 1.42 (1.22) 1.41 (1.24) 0.940 0.942 0.942
Hospital Stay 6 months 173 (83/90) 0.09 (0.29) 0.07 (0.26) 0.632 0.637 0.89512 months 165 (82/83) 0.07 (0.25) 0.07 (0.25) 0.987 0.987 0.98718 months 154 (80/74) 0.01 (0.10) 0.09 (0.28) 0.042** 0.027** 0.18624 months 165 (81/84) 0.04 (0.20) 0.06 (0.24) 0.596 0.581 0.92436 months 150 (74/76) 0.06 (0.25) 0.10 (0.30) 0.425 0.409 0.889
+ Results: IPW-adjusted impact of treatment on Child Health (2)
N (intervention
/control)
Mintervention (SD) Mcontrol (SD) IPW chi-squared/t-test
pa
IPW Permutation Test
pb
IPW Stepdown Permutation Test
pb
Accident
12 months 165 (82/83) 0.04 (0.21) 0.01 (0.10) 0.171 0.154 ~
18 months 154 (80/74) 0.08 (0.27) 0.04 (0.21) 0.387 0.405 ~24 months 165 (81/84) 0.10 (0.30) 0.10 (0.30) 0.955 0.957 ~36 months 150 (74/76) 0.12 (0.33) 0.21 (0.41) 0.162 0.159
Immunizations ~4 months 172 (82/90) 0.97 (0.18) 0.90 (0.31) 0.071* 0.045** 0.2126 months 165 (82/83) 0.98 (0.13) 0.97 (0.18) 0.584 0.597 0.59713 months 154 (80/74) 0.89 (0.32) 0.85 (0.36) 0.526 0.536 0.807
Wheezing or Asthma 12 months 165 (82/83) 0.11 (0.32) 0.10 (0.30) 0.812 0.817 0.99318 months 154 (80/74) 0.17 (0.38) 0.16 (0.37) 0.844 0.846 0.97324 months 165 (81/84) 0.08 (0.28) 0.24 (0.43) 0.019** 0.013** 0.035**36 months 150 (74/76) 0.16 (0.37) 0.17 (0.38) 0.939 0.939 0.939
Chest Infection 12 months 165 (82/83) 0.26 (0.44) 0.43 (0.50) 0.102 0.158 0.21518 months 154 (80/74) 0.29 (0.46) 0.31 (0.47) 0.746 0.750 0.93524 months 165 (81/84) 0.27 (0.45) 0.38 (0.49) 0.134 0.132 0.37536 months 150 (74/76) 0.31 (0.47) 0.33 (0.47) 0.833 0.835 0.835
+ Robustness & Additional Analyses
Conditional permutation testing Given RCT design, conditioning on covariates should not be strictly necessary,
however can improve the precision (Duflo et al., 2006)
Re-estimated results conditioning on significant baseline variables – unconditional and conditional results largely equivalent
Multiple Imputation (MI) as an alternative to IPW IPW and MI results are largely equivalent, with one extra statistically significant
result (number of health problems at 24 months) found in the MI models
Gender differences - effects for boys only Individual effects: Number of health problems at 24 months (d = 0.63), hospital
stays at 18 months (3 pp), accidents at 36 months (23.9 pp), asthma/wheezing at 24 months (22.5 pp), and chest infections at every time point (22.8 – 37.9 pp)
Stepdown effects: number of health problems, accidents, and chest infections
+ Differential misreporting & Contamination
Differential Misreporting Maternal report subject to measurement error if mothers over/under report
their child’s health Tested for differential misreporting using Social Desirability Scale-17 (SDS-17;
Stöber, 2001)
No evidence of differential misreporting
Contamination As potential for contamination in PFL is high, test using a ‘blue-dye’ question Limited evidence of contamination
Mintervention (SD) Mcontrol (SD) IPW-Perm. Test P2
Social Desirability Scale 11.19 (2.77) 11.29 (2.76) 0.540
Mintervention (SD) Mcontrol (SD) IPW Perm. Test P2
Heard the phrase ‘descriptive praise’ & accurately reports how to engage in this behavior
0.26 (0.44) 0.06 (0.24) 0.001
+Conclusion
A bundle of parenting interventions has some positive and statistically significant effects on child health
Binomial test shows probability of observing the number of reported favourable differences by chance is small
Strongest main effect on incidences of wheezing/asthma (15.5 pp reduction)
Effects driven by boys alone – consistent with Campbell et al. (2014) Number of health problems (d = 0.63), accidents (23.9 pp) and chest
infections (22.8 – 37.9 pp) Greater vulnerability of boys in the prenatal and infancy periods
Results robust to small sample size, differential attrition, multiple hypothesis testing, differential misreporting & contamination