Global Health
Mechanisms of impact of early water, sanitation, hygiene and nutrition interventions on development in middle-childhood: A causal mediation analysis Helen Pitchik* Helen Pitchik Fahmida Tofail Mahbubur Rahman Kara E. Rudolph Jennifer Ahern Peter J. Winch Stephen P. Luby Lia C. H. Fernald
Background
A cluster randomized controlled trial of individual and combined water, sanitation, hygiene (WASH), and nutrition interventions in rural Bangladesh (WASH-B) found improvements in both child diarrhea and child development outcomes at 2 years of age with a recent school-aged follow-up finding sustained impacts on development at 7 years of age. Two similar early WASH interventions in Kenya and Zimbabwe did not find intervention impacts on child development. Identifying the pathways of intervention impacts in Bangladesh will enable the design of future interventions.
Methods
We use data from the baseline, 2-, and 7- year assessments in the WASH-B intervention cohort (n=3,832 at 7 years) to examine mediators of 7-year intervention effects on child development, maternal mental health, and the home environment. We selected mediators based on a review of the literature on modifiable risk factors, data availability, and 2-year intervention impacts. We used targeted maximum likelihood estimation with ensemble machine learning to estimate the interventional direct and indirect effects through the multiple mediators, accounting for post-exposure confounding.
Results
At 2 years of age the potential mediators impacted by the WASH and nutrition interventions include indicators of child health (child 7-day diarrhea prevalence, child growth), caregiver depressive symptoms, and the quality of stimulation in the home. A preliminary analysis of the mediator-outcome associations demonstrates that stimulation at 2 years is associated with 7-year outcomes for social-emotional development, and diarrhea, home stimulation, and caregiver depressive symptoms at 2 years are associated with 7-year full-scale IQ. Results from the interventional indirect and direct effects for each mediator as well as for the combination of mediators will be presented and discussed. This work builds on evidence on key intervention components that contribute to sustained intervention effects in childhood.