Exploring the paradox: double burden of malnutrition in rural South Africa
Kimani, Elizabeth Wambui
Background: In low- to middle-income countries, rising levels of overweight and obesity are a result of multiple transitions, in particular, a nutrition transition. Consequently, in these countries, metabolic diseases are contributing increasingly to disease burden, despite the persisting burden of undernutrition and infectious diseases. Understanding the patterns and factors associated with persistent undernutrition and emerging obesity in children and adolescents, and concomitant risk for metabolic disease, is therefore of criticial importance. This should contribute to public health policy on interventions to prevent adult disease. Aims: To better understand the double burden of malnutrition in a poor, high HIV prevalent, transitional society in a middle-income country; In so doing, to inform policies and interventions to address the double burden of malnutrition. Methods: A cross-sectional growth survey was conducted in 2007 targeting 4000 children and adolescents 1-20 years of age living in rural South Africa. The survey was nested within the ongoing Agincourt Health and Socio-demographic Surveillance System, which acted as the sampling frame and also provided data for explanatory variables. Anthropometric measurements were performed on all participants using standard procedures. In addition, HIV testing was done on children aged 1 to 5 years and Tanner pubertal assessment was conducted among adolescents 9-20 years. A one-year follow-up of HIV positive children included a matched control group of HIV negative counterparts. Data collection involved both quantitative and qualitative methods. Growth z-scores were used to determine stunting, underweight and wasting and were generated using the 2006 WHO growth standards for children up to five years and the 1977 NCHS/WHO reference for older children. Overweight and obesity were determined using the International Obesity Task Force cut-offs for BMI for children aged up to 17 years and adult cut offs of BMI =25 and =30 kg/m2 for overweight and obesity respectively for adolescents 18 to 20 years. Waist circumference cut-offs of =94cm for males and =80cm for females, and waist-to-height ratio of 0.5 for both sexes, were used to determine central obesity and hence metabolic disease risk in ix adolescents. Descriptive analysis described patterns of nutritional status by age, sex, pubertal stage and HIV status. Linear and logistic regression was done to determine predictors of nutrional outcomes. A p-value of <0.05 was considered statistically significant. Results: Prevalence of undernutrition, particularly stunting, was substantial: 18% among children aged 1-4 years, with a peak of 32% in children at one year of age. Stunting and underweight were also substantial in adolescent boys, with underweight reaching a peak of 19% at 14 years of age. Concurrently, the prevalence of combined overweight and obesity, almost non-existent in boys, was prominent among adolescent girls, increasing with age, and reaching a peak of 25% at 18 years. Risk for metabolic disease using waist circumference cut-offs was substantial among adolescents, particularly girls, increasing with sexual maturation, and reaching a peak of 35% at Tanner stage 5. Prevalence of HIV in children aged 1-4 years was 4.4%. HIV positive children had poorer nutritional outcomes than that of HIV negative children in 2007. The impact of paediatric HIV on nutritional status at community level was, however, not significant. Significant predictors of undernutrition in children aged 1-4 years, documented at child, maternal, household and community levels, included child’s HIV status, age and birth weight; maternal age; age of household head; and area of residence. Significant predictors of overweight/obesity and risk for metabolic disease in adolescents aged 10-20 years, documented at individual/child and household levels included child’s age, sex and pubertal development; and household-level food security, socio-economic status, and household head’s highest education level. There was a high acceptance rate for the HIV test (95%). One year following the test, almost all caregivers had accepted and valued knowing their child’s HIV status, indicating that it enhanced their competency in caregiving. Additionally, nutritional status of HIV positive children had improved significantly within a year of follow-up. Conclusions: The study describes co-existing child stunting and adolescent overweight/obesity and risk for metabolic disease in a society undergoing nutrition transition. While likely that this profile reflects changes in nutrition and diet, variation in infectious disease burden, physical activity patterns, and social influences need to be investigated. The findings are critical in the wake of the rising public health importance of metabolic diseases in low- to middle-income countries, despite the unfinished agenda of undernutrition and infectious diseases. Clearly, policies and interventions to address malnutrition in this and other transitional societies need to be double-pronged. In addition, gender-biased nutritional patterns call for gender-sensitive policies and interventions. The study further documents a significant role of paediatric HIV on nutritional status, and the potential for community-based paediatic HIV testing to ameliorate this. Targeted early paediatric HIV testing of exposed or at risk children, followed by appropriate health care for infected children, may improve their nutritional status and survival.
PhD, Faculty of Health Sciences, University of the Witwatersrand
nutrition transition, double burden of malnutrition, stunting, underweight, wasting, overweight, obesity, metabolic disease risk, HIV, rural South Africa, low-to-middle income countries