Browsing by Author "Bourne, David"

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    Has HIV prevalence peaked in South Africa? - Can the report on the latest antenatal survey be trusted to answer this question?
    (2008) Dorrington, Rob; Bourne, David
    On the weekend of Friday 29 August, the National Department of Health placed their report on the results of the 2007 national antenatal survey, carried out a little over 10 months ago, on their website.1 The Department uses these results (showing an overall HIV prevalence of 28%) to reinforce those of the previous survey2 and argue that 'South Africa may be making some real progress in its response to the HIV epidemic' and that the 'South African HIV epidemic is on a downward trend'. While this may or may not be true, in order for one to infer a trend in indicators from a sequence of surveys they need to be comparable, year on year, with one another. Unfortunately this is not the case with the antenatal surveys of the past 2 years.
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    Infant and child mortality in South Africa in the context of a high HIV prevalence : an investigation into changing mortality patterns at a fine age resolution
    (2007) Brody, Linnea Lynn; Bourne, David
    South Africa has very high levels of HIV prevalence, with some provinces having among the highest levels in the world. Within this context it is imperative to have a clear understanding of how the epidemic is affecting infants and children in the population and to what extent interventions are affecting mortality. However, establishing accurate estimates of infant and child mortality levels is very difficult in South Africa because the data available is nearly a decade out of date. Demographic modelling techniques and extrapolations from out of date data provide the closest estimates but are less than ideal in the middle of an HIV epidemic. What is needed is a surveillance method that can provide rapid, up to date information on infant and child mortality, within an environment of high HIV prevalence that can inform health policy for South Africa's youngest citizens. This study utilized routinely collected national vital events data to describe trends in infant and child mortality from 1990 to 2006. Mortality was examined by age of death in months, a finer age resolution than has been previously published. Data used in this study consisted of unpublished mortality statistics collected by Statistics South Africa from 1990 to 2002, and data extracted from the Population Register database maintained by the Department of Home Affairs for the years 1998 to 2006. The Population Register database was investigated for use as a potential mortality surveillance tool to measure current trends in infant and child mortality and to measure any effects by HIV/IAIDS interventions at a population level. Several new and unique findings were revealed in this study. First, a new and increasing all-cause peak in mortality was discovered centring at 3 months of age - a new, previously unpublished, demographic phenomenon. Second, a coding error was found in causes of death of infants under 1 year of age in the data recorded by Statistics South Africa (Stats SA) resulting in the incorrect coding of the majority of deaths in this age group. Despite the problems with coding of cause of death, the peak in mortality at 3 months was shown to be due to HIV/AIDS mortality and was the third finding in this study. The fourth finding was that the Population Register data could further be used with the 3 month peak in mortality as a rapid surveillance tool to measure trends in infant mortality. By utilizing the up to date data from the Population Register database and monitoring the peak in mortality at 3 months, this study was able to show that HIV/AIDS interventions such as the ARV rollout and PMTCT programs are beginning to have a positive effect at a population level. This method of surveillance was able to examine changes in mortality at 3 -months at both a national and provincial level.
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    The relationship between the hardness of potable water and cardiovascular and ischaemic heart disease mortality in South African urban areas
    (1987) Derry, Christopher William; Bourne, David
    Studies carried out in a number of countries have revealed statistically significant negative correlations between death rates from cardiovascular disease (CVD) or ischaemic heart disease (IHD), and the hardness of local water supplies, a phenomenon which is known as the "water story". These findings have not, however, been universal and it was decided that a study carried out in South Africa with its high CVD and IHD death rates, might yield meaningful results to contradict or support existing findings. In 1983 a pilot study was thus initiated using a spatial model and a more detailed study began in 1984. This study ultimately involved the correlation of standardized mortality ratios (SMRs) for CVD and IHD with total water hardness and with a number of contributory and associated water quality factors. The study supported the hypothesised "water story", showing the existence of negative correlations between standardized mortality ratios (SMRs) for both CVD and IHD, and the hardness of potable water, whether measured as total hardness or as its two major contributory cations, calcium and magnesium. The level of statistical significance at which this correlation occurred, however, varied with differences in methodological approach. A "population-unweighted" methodology, which was applied to enable comparison with a number of previously published studies, pointed to potassium (a known hypertension normalisor) in permanently hard water as being an important factor. Problems inherent to each methodological approach have been discussed as has the need for improved data. In this regard, the need for a National water quality data bank has been emphasised.
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    Whither the AIDS epidemic - or lies, damned lies and statistics?
    (2003) Bourne, David
    The current HIV/AIDS pandemic is the worst plague ever to afflict humanity, and unfortunately it is at its most severe in southern Africa. Approximately 5 million people are currently infected in South Africa, and therein lies the rub, for our estimates are always based on data that contain uncertainties. While the impact on health is undeniably profound, the uncertainties around the statistics create debate. Our main source of data on the epidemic is the annual report of the Department of Health on HIV prevalence in a sample of pregnant women attending antenatal clinics in the public sector.1 This needs to be extrapolated to the general population, and to do this a series of assumptions (that may differ between different researchers) are needed. Even the population of South Africa is uncertain. While the official population in the 2001 census is 44 819 778,2 this figure is of questionable accuracy. There was an undercount of about 1 in 6 of the population,3 so assumptions and statistical models were required to arrive at the final estimate.