Aims of the study
The overall objective of this project is to assess the impact of growth charts as well as SQ-LNS on children’s physical growth in three purposely selected highly diverse areas of Zambia . This larger objective can be divided into three specific aims, as well as four sub-aims:
Specific Aim 1: Estimate the respective independent impacts of home-installed growth charts and monthly home delivery of SQ-LNS on children’s physical growth.
Specific Aim 2: Estimate the respective independent impacts of home-installed growth charts and monthly home delivery of SQ-LNS on children’s weight, haemoglobin levels and overall development.
Specific Aim 3: Estimate the joint impact of home-installed growth charts and SQ-LNS on physical growth.
We will also pursue the following sub-aims:
Sub-Aim 1: Estimate the independent and joint impacts of growth charts and SQ-LNS on micronutrient status (RBP for Vitamin A deficiency, and ferritin iron deficiency) in a sub-sample of children residing in Lusaka district
Sub-Aim 2: Estimate the independent and joint impacts of growth charts and SQ-LNS on the relative abundance of specific taxa and diversity of bacteria in the gut microbiome in a sub-sample of children residing in Lusaka district
Sub-Aim 3: Estimate the independent and joint impacts of growth charts and SQ-LNS on serum biomarkers of EED and systemic inflammation, including zonulin, intestinal fatty-acid binding protein (I-FABP), lipopolysaccharide (LPS), CRP, and AGP.
Sub-Aim 4:Estimate the independent and joint impacts of growth charts and SQ-LNS on saccadic reaction time (SRT), an eye-tracking measure of neural function.
Study design
We will conduct a multi-center 2x2 factorial, cluster-randomized controlled trial with ~2300 children and their caregivers in three geographically and culturally diverse areas of Zambia.
Study setting
This study will be in Lusaka district, Mansa district and Choma district in Zambia. These areas were selected to capture the variation in local diet, food availability, and child stunting rates across Zambia. Lusaka city is the capital of Zambia with a population of around 3 million. Study participants from Lusaka district are from predominantly urban and peri-urban areas. By contrast, Mansa district in Luapula province is 765 km from the capital city and is a predominantly rural area where the majority of the population engages in agriculture. Finally, Choma in Southern province is located 300 km South of Lusaka, and has some rural, peri-urban and urban parts. The prevalence of stunting in children <5yrs in Lusaka, Luapula and Southern provinces was 36%, 29% and 45% in 2018, respectively (24). In terms of primary crops, maize is the primary staple crop in Southern Province, while Luapula traditionally relies more on cassava.
Study participants and recruitment and inclusion criteria
A total of ~2,300 caregiver-child dyads will be enrolled in the study. Caregivers will be identified using two-stage stratified sampling procedures. In the first step, we will randomly select 90 enumeration areas from each of the three districts using the 2020 census sampling frame from the Central Statistical Office of Zambia (CSO). In a second step, we will visit all households in these areas (~250 households) to create a list of all eligible households – i.e. households with an infant between 7 and 14 months. All eligible dyads (~8 per cluster) will be visited by trained study staff, who will explain the study to caregivers and enroll them into the study conditional on their consent. Caregiver-child dyads will be excluded if they state their intention to migrate out of the study area within 12 months of the recruitment time point..
Interventions
This study aims to assess two interventions: growth charts and SQ-LNS provision.
Growth charts: Growth charts will be locally developed, placed on the walls inside homes, and allow caregivers an easy means of assessing their child’s height at home. The charts will also contain information on the importance of exclusive breastfeeding, diverse diets, frequent feeding, washing hands with soaps, and age-appropriate recipes using local foods. After the home installation of growth charts, caregivers will be given a short introduction on how to use them and how to interpret the measurements by study staff. The overall structure of the gender-specific posters is illustrated in Supplemental Materials Figure SF 1.
Small-quantity lipid-based nutrient supplements (SQ-LNS): SQ-LNS are 20 g/~110 calorie nutrient supplements that provide energy, protein, essential fatty acids and a wide range of micronutrients critical for children ages 6 to 24 months of age. The SQ-LNS used in this study will be Nutributter+, produced by Nutriset. They are designed to complement diets without displacing breastmilk and local dietary preferences and can be mixed into the child’s meal or eaten directly from the sachet. SQ-LNS has an 18-24 month shelf life, can be stored at room temperature and is not vulnerable to spoilage at high temperatures. To ensure an appropriate supply of SQ-LNS, a monthly supply of 30 sachets will be delivered to caregivers in the clusters selected for this intervention.
Primary endpoint
The primary endpoint will be children’s height and stunting (HAZ < -2) after 18 months of interventions, when children will be between 24 and 35 months old. Height will be assessed using standard anthropometric assessment kits. Height measures will be converted to height-for-age z-scores (HAZ) using the WHO anthro software package (56).
Secondary endpoints
Secondary outcomes include: weight-for-height z-score, weight-for-age z-score, hemoglobin concentration, child development (assessed through the global scales of early development) as well as the prevalence of stunting, wasting, underweight and anemia. In a sub-sample of children we will also assess micronutrient status ), inflammation, biomarkers of EED, the composition of the bacterial community in the gut microbiome, and SRT.
Measures to minimize bias
This study will be conducted as a cluster-randomized controlled trial, which should minimize the risk of selection and confounding bias. We chose to randomize at the cluster level to minimize the risk of spillover. Children’s development will be assessed objectively through trained interviewers minimizing the risk of reporting or social desirability biases.
Sample size and power calculations
The study is statistically powered (p=0.9) to detect a 0.25 SD improvement in HAZ over an 18-month period between the control group and any of the intervention arms (charts only, LNS only, combined intervention). This calculation is based on α=0.05, a follow-up rate of 85% (attrition <= 15%), and an intra-class correlation coefficient (ICC) of 0.05 (DEFF=1.95 with 20 children per cluster).
The estimated improvement in HAZ 0.25 is based on the results from the pilot study. The ICC in the pilot study was 0.02. A more conservative ICC of 0.05 was assumed for this study to ensure sufficient power.
Randomization/Sequence Generation
This is a cluster-randomized controlled trials. Clusters will be assigned with equal probability to arms 1,2, 3 and 4 using a random number draw generated by the senior author (GF) using the Stata SE 16.0 statistical software package.
Blinding/Masking
Given the nature of the interventions, blinding of participating caregivers and children is not possible. Interviewers will not be aware of the treatment group of children, and analysis will be done using concealed treatment assignment (analyst blinding).
Statistical Analysis
We will use standard linear regression models to assess the impact of the two intervention arms on child development. The primary outcome variable will be HAZ, which is normalized globally to mean zero and standard deviation 1. Cluster-robust standard errors will be used to account for the cluster-level randomization of the intervention. Separate models will be estimated with and without baseline covariates. Our primary model will be estimated following an intent-to-treat approach; we will also estimate complementary per-protocol models restricted to children complying with the two interventions. Compliance with posters will be defined as still having a poster hanging at children’s home at endline; compliance with the supplementation will be defined as having received the monthly supplements for 75% or more of the intervention period.
The final analysis will primarily rely on the data collected in the endline survey. Baseline variables will be used to 1) assess the extent to which balance was reached through the randomization and 2) create a set of control variables used in adjusted models.
Ethics
The study was approved by the Ethics Committee for North-Western Switzerland (EKNZ) as well as by the Biomedical Research Ethics Committee of the University of Zambia.
All changes to the protocol will be reported to both ethics committees.
Interim analyses
No interim analysis is foreseen.
Deviation(s) from the original statistical plan
Any deviations from the original statistical plan will be reported in the Methods section of the trial paper.
Handling of data
Missing data will arise when a participant refuses to answer a question or complete part of the examination. Missing data may also arise is a participant drops out of the study. All participants are informed that their participation is completely voluntary and that they may refuse to answer any of the questions asked and can stop the evaluation at any time as well as discontinue participation at any time without any consequences. Missing data on covariates will be imputed using multiple imputations using chained equations. Missing outcome data due to sample attrition will not be imputed; however, we will conduct and report analyses examining the extent to which attrition differed across treatment conditions.
Access to data
All data collected as part of this trial will be made publicly available (in de-identified form) after publication of the trial results.