Urban South African Adolescents Research Articles

Longitudinal patterns of physical activity, sedentary behavior and sleep in urban South African adolescents, Birth-To-Twenty Plus cohort

BackgroundAdolescence is a critical phase of human development that lays the foundation for health in later life. Of the 1.8 billion adolescents in the world, roughly 90% live in low and middle-income countries. Yet most longitudinal studies of adolescent physical activity, sedentary behavior, and sleep come from high-income countries. There is a need for a better understanding of these behaviors to inform obesity and chronic disease prevention strategies.AimsThe aim of this study is to identify longitudinal patterns and associations between physical activity, sedentary behavior and sleep in urban South African adolescents.MethodsWe analyzed data from the Birth-to-Twenty Plus Cohort (Bt20+), a longitudinal study of children in Soweto, Johannesburg, South Africa. Behaviors were self-reported annually between ages 12 and 17 y. We used Latent Class Growth Analysis to group participants into classes based on common longitudinal trajectories of time spent in informal physical activity, organized sports, walking to and from school, sedentary behavior, and school-night and weekend sleep, respectively. We performed group-based multi-trajectory modeling to identify latent clusters of individuals who followed similar trajectories of informal physical activity, organized sports and walking to and from school, and who followed similar trajectories of these three domains together with sedentary behavior and sleep.ResultsThe large majority of males (82%) and all females failed to meet the World Health Organization (WHO) physical activity recommendation for adolescents of 60 min of moderate-vigorous intensity physical activity per day. The physical activity domains clustered together in three multi-trajectory groups that define individuals’ overall physical activity pattern. While two patterns indicated decreases in physical activity throughout adolescence, one pattern, including 29% of the sample in males and 17% of the sample in females, indicated higher levels of activity throughout adolescence. Sedentary behavior and sleep trajectories did not cluster together with the physical activity domains.ConclusionMost adolescents in this South African population did not meet WHO recommendations for physical activity. In this population, trajectories of sedentary behavior and sleep were independent of physical activity.

Dietary Habits and Eating Practices and Their Association with Overweight and Obesity in Rural and Urban Black South African Adolescents.

The aim of this study was to investigate differences/similarities in dietary habits and eating practices between younger and older, rural and urban South African adolescents in specific environments (home, community and school) and their associations with overweight and obesity. Dietary habits, eating practices, and anthropometric measurements were performed on rural (n = 392, mean age = 13 years) and urban (n = 3098, mean age = 14 years) adolescents. Logistic regression analysis was used to examine the associations between dietary habits and eating practices, with overweight and obesity risk. Differences in dietary habits and eating practices by gender and by site within the three environments were identified. After adjusting for gender, site, dietary habits, and eating practices within the home, community and school environment, eating the main meal with family some days (OR = 1.78, 95% CI = 1.114–2.835; p ≤ 0.02), eating the main meal with family almost every day (OR = 1.61, 95% CI = 1.106–2.343; p ≤ 0.01), and irregular frequency of consuming breakfast on weekdays (OR = 1.38, 95% CI = 1.007–1.896; p ≤ 0.05) were all associated with increased risk of overweight and obesity. For “Year 15” adolescents, irregular frequency of consuming breakfast on weekends within the home environment (OR = 1.53, 95% CI = 1.099–2.129, p ≤ 0.01), was associated with increased risk of overweight and obesity. For both early- and mid-adolescents, being male (OR = 0.401, 95% CI = 0.299–0.537; p ≤ 0.00; OR = 0.29, 95% CI = 0.218–0.397; p ≤ 0.00) was associated with reduced risk of overweight and obesity, while residing in a rural setting (OR = 0.55, 95% CI = 0.324–0.924; p ≤ 0.02) was associated with reduced risk of overweight and obesity only among early-adolescents. Only dietary habits and eating practices within the home environment were associated with increased risk of overweight and obesity.

Socio-economic influences on anthropometric status in urban South African adolescents: sex differences in the Birth to Twenty Plus cohort.

To investigate the associations of household and neighbourhood socio-economic position (SEP) with indicators of both under- and overnutrition in adolescents and to explore sex differences. Analysis of anthropometric, household and neighbourhood SEP data from the Birth to Twenty Plus cohort born in 1990. Anthropometric outcomes were BMI (thinness, overweight and obesity) and percentage body fat (%BF; low, high). Associations between these and the household wealth index, caregiver education and neighbourhood SEP tertile measures were examined using binary logistic regression. Johannesburg-Soweto, South Africa. Adolescents aged 17-19 years (n 2019; 48·2% men). Women had a significantly higher combined prevalence of overweight/obesity (26·2%) than men (8·2%) whereas men had a significantly higher prevalence of thinness than women (22·2% v. 10·6%, respectively). Having a low neighbourhood social support index was associated with higher odds of high %BF in women (OR=1·59; 95% CI 1·03, 2·44). A low household wealth index was associated with lower odds of both overweight (OR=0·31; 95% CI 0·12, 0·76) and high %BF in men (OR=0·28; 95% CI 0·10, 0·78). A low or middle household wealth index was associated with higher odds of being thin in men (OR=1·90; 95% CI 1·09, 3·31 and OR=1·80; 95% CI 1·03, 3·15, respectively). For women, a low household wealth index was associated with lower odds of being thin (OR=0·49; 95% CI 0·25, 0·96). The study highlights that even within a relatively small urban area the nutrition transition manifests itself differently in men and women and across SEP indicators. Understanding the challenges for different sexes at different ages is vital in helping to plan public health services.

Urban South African Adolescents' Perceptions of Their Neighborhood Socio-Economic Environments: The Birth to Twenty Plus Cohort Study

The Apartheid era led to major differences in the living conditions between population groups in South Africa. Subsequently, reforms have been implemented to reduce poverty and inequalities. This study aims to assess neighborhood and school socio-economic (SE) environments reported by adolescents to determine whether geographic and population group differences in the SE environment exist. Neighborhood SE status was assessed using a novel questionnaire adapted to the urban South African context. Black African and Mixed Ancestry participants lived in more deprived SE environments and reported studying in less favorable school environments compared to Whites. Among Black Africans, those living in Soweto versus metropolitan Johannesburg reported more deprived economic and school environments.

Urban South African Adolescents' Perceptions of Their Neighborhood Socio-Economic Environments: The Birth to Twenty Plus Cohort Study

The Apartheid era led to major differences in the living conditions between population groups in South Africa. Subsequently, reforms have been implemented to reduce poverty and inequalities. This study aims to assess neighborhood and school socio-economic (SE) environments reported by adolescents to determine whether geographic and population group differences in the SE environment exist. Neighborhood SE status was assessed using a novel questionnaire adapted to the urban South African context. Black African and Mixed Ancestry participants lived in more deprived SE environments and reported studying in less favorable school environments compared to Whites. Among Black Africans, those living in Soweto versus metropolitan Johannesburg reported more deprived economic and school environments.

Residential mobility, socioeconomic context and body mass index in a cohort of urban South African adolescents

Adolescents who are changing residence, as well as their social and economic circumstances may experience lifestyle changes that have an effect on body composition outcomes such as undernutrition, overweight or obesity. This paper uses data from Birth to Twenty, a birth cohort of South African urban children, to determine the relationship between residential mobility and body mass index (BMI) amongst Black adolescents aged 15 (n=1613), and to examine the role of changes in household socioeconomic status (SES). The prevalence of overweight and obesity in the sample was 25% in females and 8% in males. Amongst the females, a strong positive association between residential mobility and BMI was observed for those who also experienced an increase in household SES between birth and 15 years (β=0.42, SE=0.13), while no effect was identified for males. The study shows the potential for environmental change and increased resources to influence the risk for obesity. It also highlights the value in considering the range of social environmental factors and changes across the early life course that might play a part in evolving nutritional patterns in urban transitioning environments.

Nicotine dependence and problem behaviors among urban South African adolescents

Tobacco use and its concomitant, nicotine dependence, are increasing in African countries and other parts of the developing world. However, little research has assessed nicotine dependence in South Africa or other parts of the African continent. Previous research has found that adolescent problem behaviors, including tobacco use, tend to cluster. This study examined the relationship between nicotine dependence and adolescent problem behaviors in an ethnically diverse sample of urban South African adolescents. A community sample (N = 731) consisting of "Black," "White," "Coloured," and "Indian" youths aged 12-17 years was drawn from the Johannesburg metropolitan area. Structured interviews were administered by trained interviewers. Nicotine dependence was assessed by the Fagerström Test of Nicotine Dependence. Logistic regression analyses showed that higher levels of nicotine dependence significantly predicted elevated levels of violent behavior, deviant behavior, marijuana and other illegal drug use, binge drinking, early sexual intercourse, multiple sexual partners, and inconsistent condom use, despite control on the adolescents' demographic characteristics, peer smoking, conflict with parents, peer deviance, and the availability of legal and illegal substances. These relationships were robust across ethnicity and gender. The findings indicate the need for policy makers and prevention and intervention programs in South Africa to consider adolescent nicotine dependence in conjunction with comorbid problem behaviors, including other substance use, sexual risk behaviors, and deviant behaviors.

Studying a Population Undergoing Nutrition Transition: A Practical Case Study of Dietary Assessment in Urban South African Adolescents

The South African Medical Research Council food frequency questionnaire (FFQ) and protocol was used to determine food intake in 83 adolescents from the Birth To Twenty study. The FFQ was piloted on a small group (n = 8). Specific problems which resulted in overestimation of energy intake were identified. The protocol was modified and administered to the remainder of the adolescents and their caregivers. Reasonable energy intakes were obtained, and time spent completing the FFQ was reduced. The modified protocol was more successful in determining habitual food intake although it would benefit from validation against other dietary intake techniques.

Is puberty starting earlier in urban South Africa?

Age at the initation of pubertal development was estimated for 401 Black (212 boys) and 206 White (100 boys) urban South African adolescents born in Soweto-Johannesburg in 1990. Average age at the initation of puberty, assessed by age at the transition from Tanner Stage 1 to Tanner Stage 2 for breast/genitalia or pubic hair development ranged between 9.8 and 10.5 years. There were no statistically significant differences in age at initiation between genders or ethnic groups. Age at the initation of pubertal development has remained stable over the last 10 to 15 years, with the exception of pubic hair in boys which has declined on average 1.3 years over a decade. There is evidence to suggest that the tempo of pubertal maturation is increasing in girls born in the Soweto-Johannesburg area, however, the evidence is less clear for boys.

Secular trends in skeletal maturity in South Africa: 1962–2001

Background: Secular trends are usually monitored through changes in size and earlier maturation. Skeletal maturity has rarely been used as a biological indicator of secular trend.Aim: To observe secular changes in the skeletal maturity of urban South African adolescents between 1962 and 2001.Subjects and methods: Data from the Pretoria National Nutrition Survey were compared with a cross-sectional survey of children from the Johannesburg–Soweto based Birth to Twenty birth cohort study. Adolescents aged 9–11 years from each survey were included in the analysis. Skeletal maturity was assessed using the Greulich–Pyle technique. Height, weight, triceps and subscapular skinfolds were also measured.Results: The skeletal maturity of white males and females in 2001 was in advance of the 1962 cohort by an average of 3.4 months and 2.0 months, respectively. Black males and females in 2001 were significantly in advance of the 1962 cohort by an average of 9.7 months and 15.8 months, respectively (p<0.01).Conclusion: Significant secular increases in the skeletal maturity of urban black South African children occurred between 1962 and 2001. Non-significant increases were seen in white children. The significant secular increases were concordant with increases in stature and adiposity during this period. The increase in skeletal maturity may reflect the removal of growth constraint, particularly in black children.

Suicide among urban South African adolescents

Knowledge of suicide epidemiology in low- and middle-income settings is important for both well-tailored policies and an increased global understanding of suicide macro-determinants. Adolescents are an important target group in that respect, and those from South Africa are a particular concern, given the additional challenges associated with dramatic political, economic, and health transition. This study presents a profile of adolescent suicide occurrence and sex, race, and city differences. Adolescents aged 10-19 years in post-apartheid urban South Africa. Sex-, race- and city-specific suicide rates were calculated for two age groups (10-14, 15-19 years). Using logistic regression, odds ratios were compiled, first adjusting for age, then additionally for sex, race, and city. Female subjects, those classified as 'coloured' (denoting mixed racial origin), and those living in Tshwane were used as reference groups. Proportions (with 95% confidence intervals) of leading suicide methods were compared. Suicide rates were considerably higher among older adolescents and varied by sex, race, and city. Males had more than twice the odds of committing suicide compared with females. In the fully adjusted model, differences between races were not significant, but city-level differences remained. The leading suicide method was hanging for males and both hanging and poisoning for females. In contemporary urban South Africa, male sex, and city of residence, but not race, were associated with the commission of adolescent suicide, which tends to occur by quite specific methods. The findings warrant research into the possible underlying contextual, demographic, and individual mechanisms.

Development of a reliable and valid nutritional knowledge questionnaire for urban South African adolescents

Objectives We wanted to develop a valid and reliable nutritional knowledge test for urban South African adolescents who were participating in the Birth-to-Twenty cohort study. The questionnaire was intended for use every second year, from ages 13 to 14 y until age 20 y. Methods Theinitial steps involved the development of a conceptual framework andidentification of nutritional concepts in collaboration withnutritional experts, and this defined the construct of thequestionnaire. The South African national teaching curriculumobjectives for nutritional education and other relevant issues wereselected as the desired concepts, and most items were phrased inaccordance with the recently developed South African Food-Based DietaryGuidelines. Thereafter, 140 items (questions) were developed and inturn assessed by an expert panel, and the result was that only 88 itemsremained. This was done to ensure content and face validity of theitems. The 88 items were constructed into a questionnaire and pilotedfor appropriateness and understanding by adolescents, ages 13 to14 y, as a means of assessing face validity by non-experts.The edited preliminary questionnaire (still with 88 items) wasadministered to a nutrition expert group ( n= 71) versus a non-expert group ( n= 82), referred to as sample 1, for the purposes of performingitem analysis and assessing construct validity of the questionnaire.The result of the analysis, a 63-item questionnaire, was administeredto adolescents at three school grade levels, 8( n = 128), 10 ( n= 143), and 12 ( n = 98),referred to as sample 2, which was representative of the grades inwhich the Birth-to-Twenty group will be in when the questionnaire isadministered. The questionnaire was administered to the sample toassess its content validity and internal consistency reliability. Thefinal questionnaire had 60 items, and its construct, content, andinternal consistency reliability werereassessed. Results Thefinal 60-item questionnaire displayed a significant difference( P < 0.0001) in the mean scores of the expertand non-expert groups tested. It had internal consistencies(Cronbach's α) of 0.71, 0.79, and 0.82 for grades 8, 10,and 12 respectively, and an overall value of 0.77 for all groupscombined. However, it was less than 0.7 for most grade 8 pupils and forall grades at a historically disadvantagedschool. Conclusion Anutritional knowledge questionnaire with construct, face, and contentvalidities and internal consistency was developed for use in SouthAfrican adolescents to evaluate their nutritional knowledge. Internalconsistency was low in children at a disadvantaged school and those ingrade 8 compared with multiracial groups at a multiracial school. It isrecommended that pupils at disadvantaged schools be assisted by trainedinterviewers when taking thetest.