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T de Wet

Publications and source records attributed to T de Wet.

13 recordsLinked to original sources
PubMed2004

The relationship between socio-economic status and physical activity patterns in South African children.

AIM: To examine: (1) the associations between socio-economic status, physical activity, anthropometric and body composition variables in South African children; (2) the influence maternal characteristics have on children's physical activity levels; and (3) associations between television watching, activity level and body composition. METHODS: In 381 South African children, physical activity and socio-economic status were assessed via structured retrospective interview using validated questionnaires. An asset indicator score was calculated as a proxy measure of socio-economic status and used to divide children into quartiles. RESULTS: Children falling into the highest socio-economic status quartile had mothers with the highest educational levels, generally came from dual parent homes, were highly physically active, watched less television, weighed more and had greater lean tissue than children in lower quartiles. A greater percentage of children living in dual parent homes and with mothers of a higher educational status were highly active compared with children living in single parent homes and with mothers of a lower educational status. We found greater levels of lean mass with increased activity level after controlling for television watching time and fat mass. There were high levels of low activity and high television watching time among lower socio-economic status groups. There were significant racial differences in patterns of activity. White children were found to be more active than black children, more likely to participate in physical education classes at school and watched less television than black children. CONCLUSION: Physical activity levels and socio-economic variables are closely related in this population of South African children.

Child↗
PubMed2001

Adolescent pregnancy and parenthood in South Africa.

South Africa's total fertility rate is estimated to be one of the lowest in sub-Saharan Africa, fewer than three births per woman nationally and declining. At the same time, adolescent childbearing levels remain high: More than 30 percent of 19-year-old girls are reported to have given birth at least once. Evidence from focus-group discussions conducted in urban and rural areas in South Africa with young black women and men, and with the parents of teenage mothers, is used to consider the experience of early parenthood, including the role of paternity, education, work opportunities, and subsequent fertility. In South Africa, in contrast to many other settings, teenage mothers may return to school once they have given birth, and this opportunity is strongly related to a long delay before the birth of a second child. Educated girls also tend to bring more bridewealth, which may encourage parents to support their daughters' schooling, and perhaps their return to school following childbirth. The support of the child, however, is often subject to paternal recognition and commitment, even though boys are unwilling to admit paternity because it jeopardizes their educational and employment opportunities.

Adaptation, Psychological↗
PubMed2000

The reliability and validity of self-reported reproductive history and obstetric morbidity amongst Birth to Ten mothers in Soweto.

OBJECTIVE: To assess whether self-reports of reproductive history and obstetric morbidity provide an accurate basis for clinical decision-making. SETTING, PARTICIPANTS AND METHODS: Self-reports of maternal age and reproductive history, together with clinical measurements of five medical disorders, were abstracted from the obstetric notes of 517 mothers whose children were enrolled in the Birth to Ten study. These data were compared to self-reported information collected by interview during the Birth to Ten study. FINDINGS: The reliability of self-reported age and gravidity was high (R = 0.810-0.993), yet self-reports of previous miscarriages, terminations, premature- and stillbirths were only fairly reliable (Kappa = 0.48-0.50). Self-reported diabetes and high blood pressure had specificities of more than 95% for glycosuria, hypertension and pre-eclampsia. However, the specificity of self-reported oedema for hypertensive disorders and the specificity of self-reported urinary tract infection for STD seropositivity were only around 65%. CONCLUSIONS: The modest reliability and limited validity of self-reported obstetric morbidity undermines the clinical utility of this information. RECOMMENDATIONS: These results strengthen the case for providing mothers with "Home-based Maternal Records" to facilitate access to accurate obstetric information during subsequent clinical consultations.

Child↗
PubMed2000

Cardiovascular disease risk factors in 5-year-old urban South African children--the Birth to Ten Study.

BACKGROUND: A birth cohort study, the Birth to Ten (BTT) study, commenced in the greater Johannesburg/Soweto metropole in South Africa in 1990. The overall BTT project collected antenatal, birth and early development information on these children as well as information that could help identify factors related to the emergence of risk of cardiovascular diseases (CVDs) in children. OBJECTIVE: To determine CVD risk profiles and their determinants in 5-year-old children living in an urban environment in South Africa. METHODS: Demographic and birth characteristics were collected on a sample of 964 5-year-olds whose parents agreed for blood samples to be taken from their children. The children's height and weight were measured using standardised procedures; blood pressure (BP) was measured with a Dinamap Vital Signs Monitor, and a non-fasting blood sample was drawn for lipid determinations. Information on exposure to tobacco smoke and additional health-related data were obtained by interview. RESULTS: No differences were found between the birth weight and gestational age of the 5-year-old CVD participants and the remainder of the children studied at birth. The systolic BP was significantly different between ethnic groups, with the BP of the black children significantly higher than that of the Indian and white children, while the diastolic BP of black children was also the highest. White children had the highest mean total cholesterol (TC) and low-density lipoprotein cholesterol (LDLC) levels, significantly higher than those in the black community. The coloured children's TC level was also significantly lower than that of the whites, while the LDLC level of the Indian children was significantly higher than that of the blacks. Overall, 64% of the children were exposed to environmental tobacco smoke (ETS), with the white group having the lowest rate (45% exposed to ETS). The coloured children were most frequently exposed to ETS, with 40.6% having primary caregivers who smoked; of these children 42% lived in homes with two or more smokers. CONCLUSIONS: Tobacco control legislation will protect South Africans against tobacco sales promotions. This will be the first step towards increasing the priority of chronic disease prevention, health promotion and appropriate care for chronic diseases and their risk factors on the South African health policy agenda. The groups of children that were studied carried differing but significant levels of CVD risk. This suggests that the promotion of a healthy lifestyle should start in childhood, and should target the risk factors found in each group.

Analysis of Variance↗
PubMed1998

Are overweight women at increased risk of obesity following pregnancy?

Longitudinal studies suggest that women who already have a high BMI are at greater risk of maternal obesity than their lighter counterparts. The aim of the present study was to investigate this possibility by examining the relationship between reproductive history and maternal BMI in a community of 627 women from South Africa with a high prevalence of obesity. Standardized questionnaires were used to obtain detailed sociodemographic and behavioural information, while maternal weight and height were both measured at the time of the interview. Analysis of covariance (ANCOVA) showed that maternal age (r2 0.015, P = 0.001), smoking status (r2 0.012, P = 0.036), and social support (r2 0.011, P = 0.006) were all independently associated with maternal BMI. If overweight women were at increased risk of maternal obesity, then the positive relationship between reproductive history and maternal BMI should be enhanced in this relatively obese community, yet the ANCOVA models showed no independent association between gravidity and maternal BMI after controlling for the effects of confounding factors. Although previous longitudinal studies have found a positive association between prepregnant weight and long-term weight gain, this relationship might arise because overweight women gain more weight over a fixed period of time than normal weight women, and therefore they may appear to be at greater risk of pregnancy-related weight gains. Overweight women are at greater risk of weight gain generally, but there is little unequivocal evidence to suggest that they are at any increased risk of maternal obesity, when compared with women of lower BMI.

Adult↗
PubMed1997

The reliability of hand-written and computerised records of birth data collected at Baragwanath hospital in Soweto.

This study examined the reliability of hand written and computerised records of birth data collected during the Birth to Ten study at Baragwanath Hospital in Soweto. The reliability of record-keeping in hand-written obstetric and neonatal files was assessed by comparing duplicate records of six different variables abstracted from six different sections in these files. The reliability of computerised record keeping was assessed by comparing the original hand-written record of each variable with records contained in the hospital's computerised database. These data sets displayed similar levels of reliability which suggests that similar errors occurred when data were transcribed from one section of the files to the next, and from these files to the computerised database. In both sets of records reliability was highest for the categorical variable infant sex, and for those continuous variables (such as maternal age and gravidity) recorded with unambiguous units. Reliability was lower for continuous variables that could be recorded with different levels of precision (such as birth weight), those that were occasionally measured more than once, and those that could be measured using more than one measurement technique (such as gestational age). Reducing the number of times records are transcribed, categorising continuous variables, and standardising the techniques used for measuring and recording variables would improve the reliability of both hand-written and computerised data sets.

Data Collection↗
PubMed1997

The use of 'racial' categories in contemporary South African health research. A survey of articles published in the South African Medical Journal between 1992 and 1996.

OBJECTIVE: In the light of growing concern about the clinical, social and political impact of 'racial' categorisation in health research, this survey aimed to re-evaluate the current use of 'racial' categories in articles published by the South African Medical Journal. SURVEY DESIGN: Any categories that might have been used or interpreted as measures of genetically determined 'racial' differences (including 'racial', ethnic and sociopolitical 'population group' categories) were included in this survey of 668 articles describing South African health research published during the past 5 years. By classifying the research contained in each of these articles it was possible to assess the importance of 'racial' categorisation in study design. The explanations given for any 'racial' differences in health were then used to evaluate the impact of 'racial' categorisation on the perception that innate characteristics were responsible. RESULTS: Three hundred and seventeen (47.5%) articles mentioned one or more 'racial' categories, 292 (43.7%) of which used 'racial' categories to describe the subjects they studied. The commonest generic labels used for these categories were "race" and "population group", while the commonest descriptive labels referred to traditional 'racial' characteristics such as phenotype, nationality and geographical origin. Only 15 (5.1%) articles fully defined the categories and labels they used, and many more used different generic and descriptive labels interchangeably. The use of 'racial' categories was highest among genetic (73.9%), descriptive (55.3%) and quasi-experimental studies (38.2%), although most used these categories simply to describe the subjects they examined. Of those 162 (24.3%) articles that discussed 'racial' differences in health, only 120 (18.0%) contained an explanation, and 60 of these suggested that inherent genetic or behavioural factors were responsible. Nine articles contained derogatory statements that could be interpreted as prejudiced or racist. CONCLUSION: The use of 'racial' categorisation remains widespread in South African health research. By using generic and descriptive labels from traditional 'racial' taxonomies, many of these articles reinforce the perception that distinct human 'races' exist. Although most of the articles failed to explain any of the 'racial' differences in health they observed, it is likely that these will be interpreted as evidence of innate genetic or behavioural differences, like those suggested by the few articles that offered explanations. The continued use of 'racial' categorisation in health research might be inevitable, particularly for examining the impact of social forces, such as apartheid and other forms of racism, that use 'racial' categories to create unequal access to health and health care. However, any studies that use 'racial' categories should be careful to avoid legitimising the biological concept of 'race', misidentifying the causes of 'racial' disparities in health and reinforcing 'racial' prejudice.

Bias↗
PubMed1996

Desegregating health statistics and health research in South Africa.

OBJECTIVE: This article aims: (i) to re-examine the use and usefulness of categorisation based on 'race', ethnicity and 'population group' membership in public health research; and (ii) to assess the consequences of using these categories for describing, analysing and redressing disparities in health within South Africa. The utility of categorisation based on 'race', ethnicity and 'population group'. Categorising populations and comparing patterns of disease between different groups of people can be a useful technique for identifying potential causes of disease. In this context, ethnicity is a valid social concept that could be used to investigate the consequences of self-ascribed identity on health. Likewise, 'population group', as defined during apartheid in South Africa, represents a valid political concept that could be used for assessing the impact of social discrimination on health. However, both these concepts are often seen, and used, as euphemisms for 'race', even though there are no genetically distinct human subspecies that can be identified and categorised as discrete 'races'. Indeed, 'race' as a biological concept has no validity in human biology. Nevertheless, categories based on 'race', ethnicity and 'population group; continue to be used in health research, and reinforce the perception that differences in disease between different 'racial', ethnic and 'population' groups are the result of heritable biological characteristics. In so doing, they undermine support for health interventions that would otherwise address the social and political origins of 'racial' and ethnic disparities in health. The utility of 'population group' for redressing the consequences of apartheid. Despite these problems, 'population group' classification provides important information for assessing the impact of apartheid on disparities in health within South Africa. Yet, the abolition of apartheid legislation is likely to result in extensive socio-economic and geographical migration that will weaken the sensitivity and specificity of 'population group' as an indicator for identifying inequalities in health. For this reason, targeting corrective action at specific population groups in order to tackle disparities in health, runs the risk of ignoring alternative social causes of inequalities in health, and ignoring disadvantaged individuals from elsewhere in the population. The continued use of 'population group' classification might also perpetuate the root cause of disparities in health, by maintaining the process used to formalise discrimination. CONCLUSION: If the purpose of health research is to monitor inequalities in health and to help target resources aimed at reducing these inequalities, then it should seek, in its language, concepts and methods to undermine the root cause of disadvantage. Health research aimed at monitoring and redressing the consequences of social disadvantage on health should therefore focus on non-biological determinants of social disparities in health. As a general rule, health researchers should avoid using categories based on 'race', ethnicity and 'population group' when collecting and analysing health data; journal editors should not accept articles that use these categories without justification; and health authorities should not collect data routinely segregated by 'race', ethnicity or 'population group'.

Bias↗
PubMed1995

Enrolment into Birth to Ten (BTT): population and sample characteristics.

The population under study in the South African longitudinal study of urban children and their families, 'Birth to Ten' (BTT), comprised all births during a 7-week period from April to June 1990 in Soweto-Johannesburg. Specification of the population base for the cohort was hampered by a number of flaws in the notification and record-keeping systems of the local authorities. As far as could be ascertained, 5460 singleton births occurred during this time to women who gave a permanent address within the defined region. Enrolment into BTT took place over the first 15 months of the study and covered the antenatal, delivery, 6-month and 1-year periods. By the end of this time, and despite a major health service strike during the delivery phase, 74% of all births (4029 cases) had been enrolled into the study. There were marked variations in levels of enrolment, however, by population group membership, residential area and place of delivery. In general, there was substantial under-enrolment of largely middle-class white women and their babies. Initial non-enrolment of specific segments of the population and attrition of the enrolled sample up to the end of the first year are discussed in the context of racial and social differentiation in South Africa.

Adolescent↗