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A 20-year Follow-Up to an Early Childhood Stimulation Program in Jamaica
Last registered on April 10, 2017

Pre-Trial

Trial Information
General Information
Title
A 20-year Follow-Up to an Early Childhood Stimulation Program in Jamaica
RCT ID
AEARCTR-0001284
Initial registration date
April 07, 2017
Last updated
April 10, 2017 10:12 AM EDT
Location(s)
Region
Primary Investigator
Affiliation
University of California, Berkeley
Other Primary Investigator(s)
PI Affiliation
The World Bank
PI Affiliation
University of Minnesota
PI Affiliation
The University of The West Indies
PI Affiliation
University of London
PI Affiliation
The University of The West Indies
PI Affiliation
The University of The West Indies
PI Affiliation
University of Chicago
PI Affiliation
University of Chicago
PI Affiliation
University of Chicago
Additional Trial Information
Status
Completed
Start date
1987-01-06
End date
2008-12-18
Secondary IDs
Abstract
A substantial literature shows that U.S. early childhood interventions have significant long-term economic benefits. There is little evidence on this question for developing countries. We report substantial effects on the earnings of participants in a randomized intervention conducted from 1987 - 1989 that gave psychosocial stimulation to growth-stunted Jamaican toddlers. The intervention consisted of weekly visits from community health workers over a 2-year period that taught parenting skills and encouraged mothers and children to interact in ways that develop cognitive and socio-emotional skills. The authors re-interviewed 105 out of 129 study participants 20 years later and found that the intervention increased earnings by 25%, enough for them to catch up to the earnings of a non-stunted comparison group identified at baseline (65 out of 84 participants).
External Link(s)
Registration Citation
Citation
Chang-Lopez, Susan et al. 2017. "A 20-year Follow-Up to an Early Childhood Stimulation Program in Jamaica." AEA RCT Registry. April 10. https://doi.org/10.1257/rct.1284-1.0
Former Citation
Chang-Lopez, Susan et al. 2017. "A 20-year Follow-Up to an Early Childhood Stimulation Program in Jamaica." AEA RCT Registry. April 10. https://www.socialscienceregistry.org/trials/1284/history/16195
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Experimental Details
Interventions
Intervention(s)
In 2007 and 2008, researchers conducted a follow-up evaluation to a 1991 Lancet paper on an early childhood intervention that took place from 1987-1989 in low-income neighborhoods in Kingston, Jamaica. The original early childhood development (ECD) program, which lasted two years, enrolled 129 stunted children aged 9-24 months. Researchers randomly assigned these children to one of four groups: a psychosocial stimulation intervention, a nutrition intervention, both interventions, or neither intervention (the comparison group). Researchers also collected data on 84 non-stunted children from the same neighborhoods to serve as an additional comparison group. The stimulation intervention included weekly home visits by trained community health workers, who encouraged and instructed mothers on how to play and interact with their children. For the nutrition intervention, health workers distributed weekly nutritional supplements to homes, as well as additional cornmeal and skimmed milk powder to discourage sharing of the supplement with other family members.

Twenty years after the end of the program, researchers followed up with the participants of the original ECD intervention, when they were about 22 years old, to measure the long-term impacts of the program. Researchers re-interviewed 105 individuals from the original cohort of stunted children, and 65 from the original comparison group of non-stunted children. Data was collected on education and labor market outcomes to identify how the program impacted adult education and earnings outcomes, as well as whether the program enabled stunted children to "catch up" with the non-stunted comparison group.
Intervention Start Date
1987-01-06
Intervention End Date
1989-11-13
Primary Outcomes
Primary Outcomes (end points)
- Income level of participants
- Average level of earnings of participants
- Years of schooling of participants
- Likelihood of receiving some college-level education
- Student status with part-time job (binary variable)
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
In 1986-1987, the Jamaican Study enrolled 129 stunted children age 9-24 months that lived in poor disadvantaged neighborhoods of Kingston, Jamaica. Stunting was defined as having a standardized height for age z-score less than -2. The children were stratified by age (above and below 16 months) and sex. Within each stratum, children were sequentially assigned to one of four groups using a randomly generated seed to begin the assignment. The four groups were (1) psychosocial stimulation (N=32), (2) nutritional supplementation (N=32), (3) both psychosocial stimulation and nutritional supplementation (N=32), and (4) a control group that received neither intervention (N=33). All children were given access to free health care regardless of the group to which they were assigned.

The stimulation intervention (comprising groups 1 and 3) consisted of two years of weekly one-hour play sessions at home with trained community health aides. The curriculum for the cognitive stimulation was based on Piagetian concepts. Mothers were encouraged to converse with their children, to label things and actions in their environments and to play educational games with their children. Particular emphasis was placed on language development, the use of praise, and on improving the self-esteem of both the child and of the mother. At age 24 months, the curriculum was enriched to include concepts such as size, shape, position, quantity, color, etc. based on the curriculum in Palmer.

The focus of the weekly play sessions was on improving the quality of the interaction between mother and child. Mothers were encouraged to continue practicing the activities and games learned during the visits on a continuing basis beyond the home visitation time. At every visit, homemade toys were brought to the home and left for the mother and child to use until the next visit when they were replaced with new ones. The intervention was innovative both for its focus on activities to promote cognitive and language development and for its emphasis on direct mother-child interactions. The nutritional intervention (comprising groups 2 and 3) was aimed at compensating for the nutritional deficiencies that may have caused stunting. The nutritional supplements were provided weekly for a two-year period. The supplements consisted of one kilogram of formula containing 66% of daily-recommended energy (calories), and 100% of daily-recommended protein. In addition, in an attempt to minimize sharing of the formula with other family members, the family also received 0.9 kilograms of cornmeal and skimmed milk powder. Despite this, sharing was common and uptake of the supplement decreased significantly during the intervention.

Of the 129 study participants, two of the participants dropped out before completion of the two-year program. The remaining 127 participants were surveyed at baseline, resurveyed immediately following the end of the two-year intervention, and again at ages 7, 11, and 18. Our analysis is based on a re-interview of the sample in 2007-08 when the participants were approximately 22 years old, some 20 years after the original intervention.

For comparison purposes, the study also enrolled a sample of non-stunted children from the same neighborhoods, where non-stunted was defined as having a height for age z-score greater than -1 standard deviations. At baseline, every fourth stunted child in the study was matched with one non-stunted child who lived nearby and was the same age (plus or minus 3 months) and sex. At age 7, this sample of 32 was supplemented with another 52 children who had been identified in the initial survey as being non-stunted and fulfilled all other inclusion criteria. While the non-stunted group was better off than the stunted group in terms of their personal development and their socioeconomic status, the non-stunted children were still living in the same economically and socially disadvantaged Kingston neighborhoods. Members of the non-stunted comparison group did not receive any of the interventions, but did receive the same free health care as those in the stunted experimental group. From age 7 onwards, this group was surveyed at the same time as the participants in the experiment. This sample is used to investigate the extent to which the early childhood stimulation intervention helped to compensate for initial disadvantage by comparing the stunted treatment group with the non-stunted external comparison group. We define complete catch-up as no difference between the treated stunted group and the non-stunted comparison group.

In order to better understand the external validity of the catch-up analysis we compare the non-stunted group to the general population using data from two surveys that are representative of urban Jamaica: (1) the 1992 Jamaican Survey of Living Conditions (JSLC) that was collected when the children were 7 years old and when most of the non-stunted sample was first surveyed, and (2) the 2008 Jamaica Labor Force (JLF) survey that was collected in the same year as the last follow-up. Unfortunately the labor supply and earnings questions in the JLF and in our survey were asked in different ways, and there was a 50% non-response rate in the JLF to the earnings questions among those who were employed. Only the education variables are directly comparable.
Experimental Design Details
Randomization Method
The initial order of group assignment was determined randomly by use of random number tables
Randomization Unit
Individual
Was the treatment clustered?
No
Experiment Characteristics
Sample size: planned number of clusters
213 children
Sample size: planned number of observations
213 children
Sample size (or number of clusters) by treatment arms
treatment groups:
1) psychosocial stimulation: 32 stunted children;
2) nutritional supplementation: 32 stunted children;
3) both psychosocial stimulation and nutritional supplementation: 32 stunted children;

control group:
1) 33 stunted children not receiving treatment;
2) additional control group of 84 non-stunted children not receiving treatment
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Name
The University of the West Indies Ethic Committee
IRB Approval Date
2007-07-23
IRB Approval Number
ECP 151,2006/2007
Post-Trial
Post Trial Information
Study Withdrawal
Intervention
Is the intervention completed?
Yes
Intervention Completion Date
November 13, 1989, 12:00 AM +00:00
Is data collection complete?
Yes
Data Collection Completion Date
December 18, 2008, 12:00 AM +00:00
Final Sample Size: Number of Clusters (Unit of Randomization)
170 children
Was attrition correlated with treatment status?
No
Final Sample Size: Total Number of Observations
170 children
Final Sample Size (or Number of Clusters) by Treatment Arms
treatment groups: 1) psychosocial stimulation: 24 stunted children; 2) nutritional supplementation: 26 stunted children; 3) both psychosocial stimulation and nutritional supplementation: 29 stunted children; control group: 1) 26 stunted children not receiving treatment; 2) additional control group of 65 non-stunted children not receiving treatment
Data Publication
Data Publication
Is public data available?
Yes
Program Files
Program Files
Yes
Program Files URL
Reports and Papers
Preliminary Reports
Relevant Papers
Abstract
There is little unequivocal evidence that nutritional supplementation of undernourished children has a beneficial effect on their mental development. The effects of nutritional supplementation, with or without psychosocial stimulation, of growth-retarded (stunted) children aged 9-24 months were assessed in a study in Kingston, Jamaica. 129 children from poor neighbourhoods were randomly assigned to four groups—control, supplemented only, stimulated only, and supplemented plus stimulated. A group of matched non-stunted children (n = 32) was also included. The supplement comprised 1 kg milk-based formula per week for 2 years, and the stimulation weekly play sessions at home with a community health aide. The children's development (DQ) was assessed on the Griffiths mental development scales. Initially the stunted groups' DQs were lower than those of the non-stunted group, and those of the control group declined during the study, increasing their deficit. Stimulation and supplementation had significant independent beneficial effects on the children's development. Estimates of the supplementation effect ranged from 2·2 (95% confidence limits — 1·4, 5·7) for the hand and eye subscale to 12·4 (5·4, 19·5) for the locomotor subscale and those for the stimulation effect from 6·4 (2·8, 10·0) for hand and eye to 10·3 (3·3, 17·3) for locomotor. The treatment effects were additive, and combined interventions were significantly more effective than either alone. These findings suggest that poor mental development in stunted children is at least partly attributable to undernutrition.
Citation
Grantham-McGregor SM, Powell CA, Walker SP, Himes JH. (1991) Nutritional supplementation, psychosocial stimulation and development of stunted children: The Jamaican study. Lancet, 338, 1-5
Abstract
OBJECTIVE: An estimated 178 million children under 5 years in developing countries experience linear growth retardation and are unlikely to attain their developmental potential. We aimed to evaluate adult benefits from early childhood stimulation and/or nutritional supplementation in growth retarded children.

PARTICIPANTS AND METHODS: In Kingston Jamaica, 129 growth retarded children aged 9-24 months took part in a two year trial of nutritional supplementation (1 kg milk-based formula per week) and /or psychosocial stimulation (weekly play sessions to improve mother-child interaction). We assessed Intelligence Quotient (IQ), educational attainment and behavior at age 22 years in 105 participants. We used multivariate regressions, weighted to adjust for loss to follow-up, to determine treatment benefits.

RESULTS: We found no significant benefits from supplementation. Participants who received stimulation reported less involvement in fights (Odds Ratio 0.36, 95% Confidence Interval (CI) 0.12,1.06) and in serious violent behavior (Odds Ratio 0.33, 95% CI 0.11, 0.93) than participants with no stimulation. They also had higher adult IQ (coefficient 6.3, 95% CI 2.2, 10.4), higher educational attainment (achievement, grade level attained and secondary exams), better general knowledge, and fewer symptoms of depression and social inhibition.

CONCLUSIONS: Early psychosocial intervention had wide ranging benefits in adulthood, which are likely to facilitate functioning in everyday life. The reductions in violent behavior are extremely important given the high levels of violence in many developing countries. The study provides critical evidence that early intervention can lead to gains in adult functioning.
Citation
Walker, Susan, Susan M Chang, Marcos Vera-Hernandez, Sally Grantham-McGregor. 2011 Early childhood stimulation benefits adult competence and reduces violent behavior. Pediatrics 127: 849-857
Abstract
This paper finds large effects on the earnings of participants from a randomized intervention that gave psychosocial stimulation to stunted Jamaican toddlers living in poverty. The intervention consisted of one-hour weekly visits from community Jamaican health workers over a 2-year period that taught parenting skills and encouraged mothers to interact and play with their children in ways that would develop their children’s cognitive and personality skills. The authors re-interviewed the study participants 20 years after the intervention. Stimulation increased the average earnings of participants by 42 percent. Treatment group earnings caught up to the earnings of a matched non-stunted comparison group. These findings show that psychosocial stimulation early in childhood in disadvantaged settings can have substantial effects on labor market outcomes and reduce later life inequality.
Citation
Gertler, Paul, James Heckman, Rodrigo Pinto, Arianna Zanolini, Christel Vermeerch, Susan Walker, Susan M. Chang, and Sally Grantham-McGregor. "Labor Market Returns to Early Childhood Stimulation: a 20-year Followup to an Experimental Intervention in Jamaica." World Bank Policy Research Working Paper #6529, July 2013.
Abstract
A substantial literature shows that U.S. early childhood interventions have significant long-term economic benefits. There is little evidence on this question for developing countries. We report substantial effects on the earnings of participants in a randomized intervention conducted in 1986–1987 that gave psychosocial stimulation to growth-stunted Jamaican toddlers. The intervention consisted of weekly visits from community health workers over a 2-year period that taught parenting skills and encouraged mothers and children to interact in ways that develop cognitive and socio-emotional skills. The authors re-interviewed 105 out of 129 study participants 20 years later and found that the intervention increased earnings by 25%, enough for them to catch up to the earnings of a non-stunted comparison group identified at baseline (65 out of 84 participants).
Citation
Gertler, Paul, James Heckman, Rodrigo Pinto, Arianna Zanolini, Christel Vermeerch, Susan Walker, Susan Chang-Lopez, and Sally Grantham-McGregor. 2014. “Labor Market Returns to an Early Childhood Stimulation Intervention in Jamaica.” Science 344(6187): 998-1001.