Jan Van den Broeck

Measurement and standardization protocols for anthropometry used in the construction of a new international growth reference

Thorough training, continuous standardization, and close monitoring of the adherence to measurement procedures during data collection are essential for minimizing random error and bias in multicenter studies. Rigorous anthropometry and data collection protocols were used in the WHO Multicentre Growth Reference Study to ensure high data quality. After the initial training and standardization, study teams participated in standardization sessions every two months for a continuous assessment of the precision and accuracy of their measurements. Once a year the teams were restandardized against the WHO lead anthropometrist, who observed their measurement techniques and retrained any deviating observers. Robust and precise equipment was selected and adapted for field use. The anthropometrists worked in pairs, taking measurements independently, and repeating measurements that exceeded preset maximum allowable differences. Ongoing central and local monitoring identified anthropometrists deviating from standard procedures, and immediate corrective action was taken. The procedures described in this paper are a model for research settings.The World Health Organization (WHO) Multicentre Growth Reference Study (MGRS) is a community-based, multicountry project to develop new growth references for infants and young children. The design combines a longitudinal study from birth to 24 months with a cross-sectional study of children aged 18 to 71 months. The pooled sample from the six participating countries (Brazil, Ghana, India, Norway, Oman, and the United States) consists of about 8,500 children. The study subpopulations had socioeconomic conditions favorable to growth, and low mobility, with at least 20% of mothers following feeding recommendations and having access to breastfeeding support. The individual inclusion criteria were absence of health or environmental constraints on growth, adherence to MGRS feeding recommendations, absence of maternal smoking, single term birth, and absence of significant morbidity. In the longitudinal study, mothers and newborns were screened and enrolled at birth and visited at home 21 times: at weeks 1, 2, 4, and 6; monthly from 2 to 12 months; and every 2 months in their second year. In addition to the data collected on anthropometry and motor development, information was gathered on socioeconomic, demographic, and environmental characteristics, perinatal factors, morbidity, and feeding practices. The prescriptive approach taken is expected to provide a single international reference that represents the best description of physiological growth for all children under five years of age and to establish the breastfed infant as the normative model for growth and development.

Data cleaning: detecting, diagnosing, and editing data abnormalities.

In this policy forum the authors argue that data cleaning is an essential part of the research process, and should be incorporated into study design.

Zinc or multiple micronutrient supplementation to reduce diarrhea and respiratory disease in South African children: a randomized controlled trial.

Background Prophylactic zinc supplementation has been shown to reduce diarrhea and respiratory illness in children in many developing countries, but its efficacy in children in Africa is uncertain. Objective To determine if zinc, or zinc plus multiple micronutrients, reduces diarrhea and respiratory disease prevalence. Design Randomized, double-blind, controlled trial. Setting Rural community in South Africa. Participants Three cohorts: 32 HIV-infected children; 154 HIV-uninfected children born to HIV-infected mothers; and 187 HIV-uninfected children born to HIV-uninfected mothers. Interventions Children received either 1250 IU of vitamin A; vitamin A and 10 mg of zinc; or vitamin A, zinc, vitamins B1, B2, B6, B12, C, D, E, and K and copper, iodine, iron, and niacin starting at 6 months and continuing to 24 months of age. Homes were visited weekly. Outcome Measures Primary outcome was percentage of days of diarrhea per child by study arm within each of the three cohorts. Secondary outcomes were prevalence of upper respiratory symptoms and percentage of children who ever had pneumonia by maternal report, or confirmed by the field worker. Results Among HIV-uninfected children born to HIV-infected mothers, median percentage of days with diarrhea was 2.3% for 49 children allocated to vitamin A; 2.5% in 47 children allocated to receive vitamin A and zinc; and 2.2% for 46 children allocated to multiple micronutrients (P = 0.852). Among HIV-uninfected children born to HIV-uninfected mothers, median percentage of days of diarrhea was 2.4% in 56 children in the vitamin A group; 1.8% in 57 children in the vitamin A and zinc group; and 2.7% in 52 children in the multiple micronutrient group (P = 0.857). Only 32 HIV-infected children were enrolled, and there were no differences between treatment arms in the prevalence of diarrhea. The prevalence of upper respiratory symptoms or incidence of pneumonia did not differ by treatment arms in any of the cohorts. Conclusion When compared with vitamin A alone, supplementation with zinc, or with zinc and multiple micronutrients, did not reduce diarrhea and respiratory morbidity in rural South African children. Trial Registration ClinicalTrials.gov NCT00156832

Sociodemographic, lifestyle, mental health and dietary factors associated with direction of misreporting of energy intake.

OBJECTIVE To estimate the extent of under- and over-reporting, to examine associations with misreporting and sociodemographic and lifestyle characteristics and mental health status and to identify differential reporting in micro- and macronutrient intake and quality of diet. DESIGN A health and lifestyle questionnaire and a semi-quantitative FFQ were completed as part of the 2007 Survey of Lifestyle, Attitudes and Nutrition. Energy intake (EI) and intake of micro- and macronutrients were determined by applying locally adapted conversion software. A dietary score was constructed to identify healthier diets. Accuracy of reported EI was estimated using the Goldberg method. ANOVA, χ2 tests and logistic regression were used to examine associations. SETTING Residential households in Ireland. SUBJECTS A nationally representative sample of 7521 adults aged 18 years or older. RESULTS Overall, 33·2 % of participants were under-reporters while 11·9 % were over-reporters. After adjustment, there was an increased odds of under-reporting among obese men (OR = 2·01, 95 % CI 1·46, 2·77) and women (OR = 1·68, 95 % CI 1·23, 2·30) compared to participants with a healthy BMI. Older age, low socio-economic status and overweight/obesity reduced the odds of over-reporting. Among under-reporters, the percentage of EI from fat was lower and overall diet was healthier compared to accurate and over-reporters. The reported usage of salt, fried food consumption and snacking varied significantly by levels of misreporting. CONCLUSIONS Patterns in differential reporting were evident across sociodemographic, lifestyle and mental health factors and diet quality. Consideration should be given to how misreporting affects nutrient analysis to ensure sound nutritional policy.

Fast-food and sweetened beverage consumption: association with overweight and high waist circumference in adolescents

OBJECTIVE Overweight and obesity have increased to epidemic proportions among adolescents and are associated with chronic non-communicable diseases and excess mortality in adulthood. The association of overweight/obesity with poor dietary habits has not been studied in adolescents in middle-income developing countries. The present study aimed to estimate the prevalence of overweight, obesity and high waist circumference (WC) in 15-19-year-old Jamaican adolescents and to investigate the association with fast-food and sweetened beverage consumption. DESIGN The study enrolled 1317 (598 male, 719 female) adolescents aged 15-19 years using multistage, nationally representative sampling. Age-specific prevalence calculation used internal Z-score lines connecting with the WHO adult cut-off points. Logistic regression was used to examine the association of overweight or high WC with fast-food and sweetened beverage consumption, adjusting for potential confounders. RESULTS The overall prevalence of overweight, obesity and high WC was approximately 15 %, 6 % and 10 %, respectively. Prevalence estimated using internal Z-scores was similar to that using the International Obesity Taskforce cut-off points. Obesity (8.0 % in females, 3.3 % in males) and high WC (16.2 % in females, 1.7 % in males) were significantly more prevalent in females when using internal Z-score cut-offs. High WC was associated with the absence of fruit consumption (P = 0.043) and overweight with high sweetened beverage consumption (P = 0.018). CONCLUSION Overweight occurs frequently among Jamaican 15-19-year-olds and is associated with increased consumption of sweetened beverages. High WC is more prevalent among females and is related to low consumption of fruits and vegetables. Measures to reduce the consumption of sweetened beverages and increase fruit intake may reduce the prevalence of excess body fat among adolescents.

Prevalence of the metabolic syndrome and its components in relation to socioeconomic status among Jamaican young adults: a cross-sectional study.

BackgroundThe metabolic syndrome has a high prevalence in many countries and has been associated with socioeconomic status (SES). This study aimed to estimate the prevalence of the metabolic syndrome and its components among Jamaican young adults and evaluate its association with parental SES.MethodsA subset of the participants from the 1986 Jamaica Birth Cohort was evaluated at ages 18-20 years between 2005 and 2007. Trained research nurses obtained blood pressure and anthropometric measurements and collected a venous blood sample for measurement of lipids and glucose. Prevalence of the metabolic syndrome and its components were estimated using the 2009 Consensus Criteria from the International Diabetes Federation, National Heart Lung and Blood Institute, American Heart Association, World Heart Federation, International Atherosclerosis Society, and International Association for the Study of Obesity. SES was assessed by questionnaire using occupation of household head, highest education of parent/guardian, and housing tenure of parent/guardian. Analysis yielded means and proportions for metabolic syndrome variables and covariates. Associations with levels of SES variables were obtained using analysis of variance. Multivariable analysis was conducted using logistic regression models.ResultsData from 839 participants (378 males; 461 females) were analyzed. Prevalence of the metabolic syndrome was 1.2% (95% confidence interval [95%CI] 0.5%-1.9%). Prevalence was higher in females (1.7% vs. 0.5%). Prevalence of the components [male: female] were: central obesity, 16.0% [5.3:24.7]; elevated blood pressure, 6.7% [10.8:3.3]; elevated glucose, 1.2% [2.1:0.4]; low HDL, 46.8% [28.8:61.6]; high triglycerides, 0.6% [0.5:0.6]. There were no significant differences in the prevalence of the metabolic syndrome for any of the SES measures used possibly due to lack of statistical power. Prevalence of central obesity was inversely associated with occupation (highly skilled 12.4%, skilled 13.5%, semi-skilled/unskilled 21.8%, p = 0.013) and education (tertiary 12.5%, secondary 14.1%, primary/all-age 28.4%, p = 0.002). In sex-specific multivariate logistic regression adjusted for hip circumference, central obesity remained associated with occupation and education for women only.ConclusionPrevalence of the metabolic syndrome is low, but central obesity and low HDL are present in 16% and 47% of Jamaican youth, respectively. Central obesity is inversely associated with occupation and education in females.

Effect on longitudinal growth and anemia of zinc or multiple micronutrients added to vitamin A: a randomized controlled trial in children aged 6-24 months.

BackgroundThe benefits of zinc or multiple micronutrient supplementations in African children are uncertain. African children may differ from other populations of children in developing countries because of differences in the prevalence of zinc deficiency, low birth weight and preterm delivery, recurrent or chronic infections such as HIV, or the quality of complementary diets and genetic polymorphisms affecting iron metabolism.The aim of this study was to ascertain whether adding zinc or multiple micronutrients to vitamin A supplementation improves longitudinal growth or reduces prevalence of anemia in children aged 6-24 months.MethodsRandomized, controlled double-blinded trial of prophylactic micronutrient supplementation to children aged 6-24 months. Children in three cohorts - 32 HIV-infected children, 154 HIV-uninfected children born to HIV-infected mothers, and 187 uninfected children born to HIV-uninfected mothers - were separately randomly assigned to receive daily vitamin A (VA) [n = 124], vitamin A plus zinc (VAZ) [n = 123], or multiple micronutrients that included vitamin A and zinc (MM) [n = 126].ResultsAmong all children there were no significant differences between intervention arms in length-for-age Z scores (LAZ) changes over 18 months. Among stunted children (LAZ below -2) [n = 62], those receiving MM had a 0.7 Z-score improvement in LAZ versus declines of 0.3 in VAZ and 0.2 in VA (P = 0.029 when comparing effects of treatment over time). In the 154 HIV-uninfected children, MM ameliorated the effect of repeated diarrhea on growth. Among those experiencing more than six episodes, those receiving MM had no decline in LAZ compared to 0.5 and 0.6 Z-score declines in children receiving VAZ and VA respectively (P = 0.06 for treatment by time interaction). After 12 months, there was 24% reduction in proportion of children with anemia (hemoglobin below 11 g/dL) in MM arm (P = 0.001), 11% in VAZ (P = 0.131) and 18% in VA (P = 0.019). Although the within arm changes were significant; the between-group differences were not significant.ConclusionsDaily multiple micronutrient supplementation combined with vitamin A was beneficial in improving growth among children with stunting, compared to vitamin A alone or to vitamin A plus zinc. Effects on anemia require further study.Trial registrationThis study is registered with ClinicalTrials.gov, number .NCT00156832.

Incidence and duration of severe wasting in two African populations

OBJECTIVE The present study aimed to compare two situations of endemic malnutrition among <5-year-old African children and to estimate the incidence, the duration and the case fatality of severe wasting episodes. DESIGN Secondary analysis of longitudinal studies, conducted several years ago, which allowed incidence and duration to be calculated from transition rates. The first site was Niakhar in Senegal, an area under demographic surveillance, where we followed a cohort of children in 1983-5. The second site was Bwamanda in the Democratic Republic of Congo, where we followed a cohort of children in 1989-92. Both studies enrolled about 5,000 children, who were followed by routine visits and systematic anthropometric assessment, every 6 months in the first case and every 3 months in the second case. RESULTS Niakhar had less stunting, more wasting and higher death rates than Bwamanda. Differences in cause-specific mortality included more diarrhoeal diseases, more marasmus, but less malaria and severe anaemia in Niakhar. Severe wasting had a higher incidence, a higher prevalence and a more marked age profile in Niakhar. However, despite the differences, the estimated mean durations of episodes of severe wasting, calculated by multi-state life table, were similar in the two studies (7.5 months). Noteworthy were the differences in the prevalence and incidence of severe wasting depending on the anthropometric indicator (weight-for-height Z-score <or=-3.0 or mid upper-arm circumference <110 mm) and the reference system (National Center for Health Statistics 1977, Centers for Disease Control and Prevention 2000 or Multicentre Growth Reference Study 2006). CONCLUSIONS Severe wasting appeared as one of the leading cause of death among under-fives: it had a high incidence (about 2 % per child-semester), long duration of episodes and high case fatality rates (6 to 12 %).

Maintaining data integrity in a rural clinical trial.

Background Clinical trials conducted in rural resource-poor settings face special challenges in ensuring quality of data collection and handling. The variable nature of these challenges, ways to overcome them, and the resulting data quality are rarely reported in the literature. Purpose To provide a detailed example of establishing local data handling capacity for a clinical trial conducted in a rural area, highlight challenges and solutions in establishing such capacity, and to report the data quality obtained by the trial. Methods We provide a descriptive case study of a data system for biological samples and questionnaire data, and the problems encountered during its implementation. To determine the quality of data we analyzed test—retest studies using Kappa statistics of inter- and intra-observer agreement on categorical data. We calculated Technical Errors of Measurement of anthropometric measurements, audit trail analysis was done to assess error correction rates, and residual error rates were calculated by database-to-source document comparison. Results Initial difficulties included the unavailability of experienced research nurses, programmers and data managers in this rural area and the difficulty of designing new software tools and a complex database while making them error-free. National and international collaboration and external monitoring helped ensure good data handling and implementation of good clinical practice. Data collection, fieldwork supervision and query handling depended on streamlined transport over large distances. The involvement of a community advisory board was helpful in addressing cultural issues and establishing community acceptability of data collection methods. Data accessibility for safety monitoring required special attention. Kappa values and Technical Errors of Measurement showed acceptable values. Residual error rates in key variables were low. Limitations The article describes the experience of a single-site trial and does not address challenges particular to multi-site trials. Conclusions Obtaining and maintaining data integrity in rural clinical trials is feasible, can result in acceptable data quality and can be used to develop capacity in developing country sites. It does, however, involve special challenges and requirements. Clinical Trials 2007; 4: 572—582. http://ctj.sagepub.com

Child Mortality as Predicted by Nutritional Status and Recent Weight Velocity in Children under Two in Rural Africa

WHO has released prescriptive child growth standards for, among others, BMI-for-age (BMI-FA), mid-upper arm circumference-for-age, and weight velocity. The ability of these indices to predict child mortality remains understudied, although growth velocity prognostic value underlies current growth monitoring programs. The study aims were first to assess, in children under 2, the independent and combined ability of these indices and of stunting to predict all-cause mortality within 3 mo, and second, the comparative abilities of weight-for-length (WFL) and BMI-FA to predict short-term (<3 mo) mortality. We used anthropometry and survival data from 2402 children aged between 0 and 24 mo in a rural area of the Democratic Republic of Congo with high malnutrition and mortality rates and limited nutritional rehabilitation. Analyses used Cox proportional hazard models and receiver operating characteristic curves. Univariate analysis and age-adjusted analysis showed predictive ability of all indices. Multivariate analysis without age adjustment showed that only very low weight velocity [HR = 3.82 (95%CI = 1.91, 7.63); P < 0.001] was independently predictive. With age adjustment, very low weight velocity [HR = 3.61 (95%CI = 1.80, 7.25); P < 0.001] was again solely retained as an independent predictor. There was no evidence for a difference in predictive ability between WFL and BMI-FA. This paper shows the value of attained BMI-FA, a marker of wasting status, and recent weight velocity, a marker of the wasting process, in predicting child death using the WHO child growth standards. WFL and BMI-FA appear equivalent as predictors.