3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item The impact of dietary habits and practices during adolescence on the risk of obesity: the birth to twenty cohort(2013-04-29) Feeley, Alison Bridget BernadetteBackground: South Africa is not exempt from the obesity epidemic and latest figures show that a third of adult men and two-thirds of adult women are either overweight or obese. Concomitant are changes in dietary habits and practices which have been implicated in the risk of obesity. Concern is that obesity and related non-communicable diseases (NCDs) manifest at younger ages. Adolescence, as well as being a stage during the life course when eating attitudes and behaviours are formed, is a particular time when the aetiology of NCDs becomes evident. Little is known about the dietary patterns during adolescence in South Africa, and if policymakers are to attempt to reduce the burgeoning statistics relating to obesity then it is important to understand adolescent dietary habits and eating practices. Aims: To describe adolescent dietary habits and practices among South African adolescents and how they might influence obesity risk. Methods: This study used a mixed methods study design, using both historical and prospective data and included four study components in both an urban (components 1-3) and a rural setting (component 4). Firstly, a cross-sectional assessment of fast-food intake of urban 17-year-olds from the Birth to Twenty Cohort (Bt20); secondly, a longitudinal descriptive analysis of dietary habits and practices of the Bt20 participants over a five-year period, between ages 13 – 17 years followed; thirdly a longitudinal assessment of the relationship between dietary habits, change in socio-economic status (SES) and obesity in the Bt20 adolescents was conducted; and finally, an exploratory survey assessing the availability of fast foods in a rural area. Results: The cross-sectional analysis showed that mean fast food intake was 8.1 (4.6) items and 7.2 (4.7) items/week for males and females respectively. Furthermore, the kota (or quarter) was the most popular fast food item and on average it provided 5 370 kJ, 51 g fat (of which 13 g Saturate fatty acids (SFA)). The longitudinal analysis showed that poor dietary habits and practices were embedded by the age of 13 years and were characterised by: high fast food consumption with at least five items/week consumed from the age of 13 years. Breakfast (weekday and weekend) consumption declined for both genders and females ate breakfast less regularly than males. Snacking while watching television increased with age: with females consuming more (4.0 (4.8) - 7.3 (5.9)) snacks per week than males (3.3 (4.5) - 6.0 (5.8). Two-thirds of participants ate their main meal with their family but among girls there was a trend towards eating this meal less regularly with increasing age. Confectionery consumption remained the same, around nine items/week for males and 10 items/week for females. Lunch box usage declined with age, conversely the number of tuck shop purchases increased with age. The prevalence of combined overweight and obesity was (8.1%) and (27%) in 17-year-old males and females respectively. In males only, soft drink consumption was associated with obesity denoted by BMI z-score and fat mass (p<0.05). In the final multivariate model, soft drink consumption remained positively and significantly associated with both outcomes and „acquiring‟ a fridge over the 12-year period remained negatively associated with both BMI z-score and fat mass (p<0.001). Among females, no associations were found. Thus further data on other lifestyle variables are needed to understand better the exposures related to obesity risk in females. In the rural setting fast food was found to be available albeit a limited variety; two-thirds of the collected samples were either vetkoek (fried dough balls) or fried chips (yielding between 943 kJ – 5 552 kJ and 11 g – 64 g fat). Compared to the kotas available in Soweto, the samples obtained in the rural setting contained more energy and fat (6 300 kJ, 60 g fat vs. 5 369 kJ, 51.5 g fat). Conclusions: This research highlights that poor dietary habits and practices prevail in adolescence which may be implicated in negative health outcomes in later life. Of concern is the finding that poor dietary habits were embedded by the age of 13 years which suggests that interventions need to target families and children prior to adolescence in order to reduce the pervasiveness of these habits in the older child. The prevalence of combined overweight and obesity is higher than the national statistics for both boys and girls at the age of 17-years. This research confirms that some dietary behaviours are associated with obesity risk namely soft drink consumption – but in males only. However soft drink consumption may be a marker for other lifestyle behaviours associated with obesity. Other dietary habits were not shown to be associated with obesity in neither males nor females, which highlights the difficulty in the measurement of exposures relating to diet. This study also showed in males at least, that socio-economic factors are important when considering obesity risk. The availability of fast foods in a relatively impoverished rural area is concerning as it may indicate that this community is undergoing nutritional changes such as those seen in urban environments. With urbanisation and economic transition, households experience a change in SES and these changes drive behaviour which can either enable or disable health outcomes. In this study SES improvement, e.g. fridge ownership seems to enable certain behaviours which can be obesogenic. However we cannot halt development in this context but we must devise ways to improve lifestyle choices which will promote health rather than impede it.Item Migrant women in sex work: does urban space impact self-(re)presentation in Hillbrow, Johannesburg(2011-07-06) Oliveira, Elsa AlexandraRationale: Urbanization is rapidly taking place in Africa: fifty percent of the continent‘s population is expected to be living in urban areas by 2030 (Kok and Collinson in Vearey 2010b). Both internal1 and cross-border migrants2 are moving into South Africa’s urban centers at a faster rate than her neighboring countries; approximately 60 percent of the population is estimated to be urban (ibid). The worldwide increase in urbanization requires that research recognize the trajectories of people moving into these urban spaces, as well as the experiences that people encounter as they navigate urban centers (Kihato, 2010, Landau 2006a, 2006b, Vearey 2010a, 2010b, Venables, 2010). Many migrants in inner-city Johannesburg engage in unconventional survival strategies, including sex work (e.g. Richter 2010). Although sex work is considered an informal livelihood strategy, it is currently illegal in South Africa (UNAIDS, 2009). Research on sex work in South Africa is limited; however, there is significant evidence that sex workers in inner-city Johannesburg experience unsafe, unhealthy- often times violent- working and living conditions (e.g. Nyangairi, 2010, Richeter, 2010). This research is primarily interested in exploring the ways in which “marginalized” urban migrant groups choose to represent themselves versus the incomplete (re) presentation that is often relegated to them. A focus on representation will provide an opportunity for policy makers, programmers and academics to gain insight and better comprehend the experiences of migrant urban populations. In this case, the researcher is looking specifically at migrant women who sell sex as an entry point into the larger issues of (re) presentation among individuals and communities who are often described as “vulnerable” and/or “marginal”. Aim: The aim of this research project is to explore how migrant women who sell sex in Hillbrow, Johannesburg (re) present themselves, and how (or not) urban space affects these self- (re) presentations. Methods: The epistemological framework for the methodologies used in this study was Participatory Action Research (PAR), and the primary data collection methodology used consisted of an eleven-day participatory photo project where the research participants were given digital cameras and asked to photograph the “story” that they would like to share. Upon completion of the participatory photo workshop, five research participants were randomly selected to participate in 2-3 sessions of in-depth, semi-structured narrative interviews where the researcher explored the choice of photos taken, as well as the reasons why the photos were selected to (re) present themselves. Conclusion: This study has shown that use of Participatory Action Research as an epistemological framework is both conducive and appropriate when researching ‘hard to reach’ groups of people residing in complex urban areas. Furthermore, this research signals the need for greater inclusion of participants in studies aimed at understanding individual/group experience, especially when working with marginalized communities. This study also reveals a host of future research opportunities for those interested in exploring: (1) identity in urban space/urban health, (2) livelihood experiences/strategies of people living in densely populated urban spaces, (3) issues of belonging and access to health care, (4) impacts of structural violence on the lives of migrant women sex workers, (6) ways that perceptions and representations are impacted in group settings, and (5) the use of ‘innovative methodologies’ as a viable tool in social science research.Item Risk factors associated with TB incidence in an adult population from poorly resourced South African urban communities with a high TB prevalence(2011-03-10) Ncayiyana, Jabulani RonnieIntroduction: Tuberculosis (TB) persists as a serious global public heath problem of a magnitude requiring urgent attention. The increase in new cases of TB in African countries where the prevalence of HIV is relatively low has been associated with other host and environmental factors. There is little or no comparable data on the association between host and environmental related factors and TB incidence in low HIV prevalence regions of South Africa. Objectives: This study aims to investigate host and environmental factors associated with incident TB in one region of South Africa. Methods: 3493 TB-free participants were recruited, and baseline data collected at the beginning of 2003 in the Lung Health Study in Ravensmead and Uitsig, Cape Town, South Africa. The TB register was used to identify new cases among the 3493 participants between 2003 and 2007. Results: Of the 3493 study participants, 109 developed TB; i.e. 57 males and 52 females. The incidence of TB in the Ravensmead and Uitsig study population was 632 per 100 000. Cohabiting, OR= 2.09 (95% CI= 1.05 - 4.17), smoking, OR= 2.19 (95% CI= 1.48 - 4.14), and history of imprisonment OR= 1.88 (95% CI= 1.09 - 3.23) were all statistically associated with TB incidence in multiple logistic regression models. The summary population attributable fraction for these three factors was 53.2%. Conclusions: TB incidence was high in this community. Cigarette smoking was one of the most important predictors of TB incidence, and the proportion of smokers in this population was relatively high. TB control and prevention strategies need to focus on interventions which will reduce or limit the impact of TB risk factors.Item Item Statistical approaches for classifying & defining areas in South Africa as "urban" or "rural"(2007-10-10T07:37:16Z) Laldaparsad, SharthiThe purpose of this research report is to utilise appropriate statistical (both non-spatial and spatial) techniques to classify areas in the country into urban and rural. These areas, as derived by means of each statistical method, are profiled and common characteristics amongst them are summarised for classification and definition of urban and rural areas. Population data for these areas were aggregated to determine the overall urbanisation for the country. The methodology utilised was that of supervised classification. Two sample data sets of areas that are known with certainty to be urban or rural were derived and used consistently throughout the study. The importance of utilising areas of known urban and rural status was firstly to identify essential patterns or predominant characteristics from areas that are known, and thereafter to apply similar characteristics to areas that are not known or are ambiguous, in order to classify them as either urban or rural. Sample 1 comprises all areas in the country with formal and informal urban settlements, as well as formal rural areas, i.e. farms. Sample 2 is similar to sample 1, but in addition it includes areas falling under the jurisdiction of traditional authorities, known as tribal areas, which were classed as known rural. Non-spatial techniques, namely linear logistic regression, classification trees and discriminant analysis, as well as spatial techniques, namely straight-majority-rule and iterated conditional modes (ICM), were researched, applied and analysed for both samples, for each province and for South Africa as a whole, using the 2001 South African population census data. Comparisons were made with the 1996 census information. All three non-spatial statistical methods gave insight into those census variables and their combinations that best describe the subject under research, i.e. urban and rural. All three methods identified significant variables that clearly separate urban and rural areas. The results of all three non-spatial statistical methods showed similarities within each sample, but differences were noted between the two samples. All three nonspatial statistical methods applied to sample 1 classified the majority of the tribal EAs (Enumeration Areas) as urban, whilst the results from sample 2 are very similar to those obtained from both censuses, since both censuses and sample 2 predefine tribal settlements as rural.