Faculty of Health Sciences
Permanent URI for this communityhttps://wiredspace.wits.ac.za/handle/10539/8707
For queries relating to content and technical issues, please contact IR specialists via this email address : openscholarship.library@wits.ac.za, Tel: 011 717 4652 or 011 717 1954
Browse
443 results
Search Results
Item CD4+ T-cell count at antiretroviral therapy initiation in the "Treat AII" era in South A: an interrupted time series analysis.(2012-11-05) Yapa HM; Kim H-y; Post FA; Jiamsakul A; de Neve J-W; Tanser F; Iwuji C; Baisley K; Shamanesh M; Pillay D; Siedner MJ; Barnighausen T; Bot JItem Estimates of HIV incidence among drug users in St. Petersburg, Russia: continued growth of a rapidly expanding epidemic(2010-07-30) Linda M. Niccolai; Sergei V. Verevochkin; Olga V. Toussova; Edward White; Russell Barbour; Andrei P. Kozlov; Robert HeimerBackground: Russia has one of the world’s fastest growing HIV epidemics and it has been largely concentrated among injection drug users (IDU). St Petersburg, Russia’s second largest city, is one of the country’s regions that has been most affected by the HIV epidemic. To monitor the current epidemic situation, we sought to estimate recent HIV incidence among IDU in St Petersburg. Methods: In a cross-sectional study of 691 IDU recruited during 2005–08, HIV incidence was estimated by two methods: a retrospective cohort analysis and BED capture enzyme immunoassay (EIA) results. Socio-demographic and behavioural correlates of incident infections and spatial patterns were examined. Results: In the retrospective cohort analysis, the incidence rate was estimated to be 14.1/100 person-years [95% confidence interval (CI) 10.7–17.6]. Using results of BED EIA and two correction formulas for known misclassification, incidence estimates were 23.9 (95% CI 17.8–30.1) and 25.5 (95% CI 18.9–32.0) per 100 person-years. Independent correlates of being recently infected included current unemployment (P = 0.004) and not having injected drugs in the past 30 days (P = 0.03). HIV incident cases were detected in all but one district in the city, with focal areas of transmission observed to be expanding. Conclusions: High HIV incidence among IDU in St Petersburg attests to continued growth of the epidemic. The need for expansion of HIV prevention interventions targeted to vulnerable populations throughout the city is urgent. These results also suggest that the BED EIA may over-estimate incidence even after correction for low specificity.Item Performance of four computer-coded verbal autopsy methods for cause of death assignment compared with physician coding on 24,000 deaths in low- and middle-income countries(2014) Nikita Desai; Lukasz Aleksandrowicz; Pierre Miasnikof; Ying Lu; Jordana Leitao; Peter Byass; Stephen Tollman; Paul Mee; Dewan Alam; Suresh Kumar Rathi; Abhishek Singh; Rajesh Kumar; Faujdar Ram; Prabhat JhaBackground: Physician-coded verbal autopsy (PCVA) is the most widely used method to determine causes of death (CODs) in countries where medical certification of death is uncommon. Computer-coded verbal autopsy (CCVA) methods have been proposed as a faster and cheaper alternative to PCVA, though they have not been widely compared to PCVA or to each other. Methods: We compared the performance of open-source random forest, open-source tariff method, InterVA-4, and the King-Lu method to PCVA on five datasets comprising over 24,000 verbal autopsies from low- and middle-income countries. Metrics to assess performance were positive predictive value and partial chance-corrected concordance at the individual level, and cause-specific mortality fraction accuracy and cause-specific mortality fraction error at the population level. Results: The positive predictive value for the most probable COD predicted by the four CCVA methods averaged about 43% to 44% across the datasets. The average positive predictive value improved for the top three most probable CODs, with greater improvements for open-source random forest (69%) and open-source tariff method (68%) than for InterVA-4 (62%). The average partial chance-corrected concordance for the most probable COD predicted by the open-source random forest, open-source tariff method and InterVA-4 were 41%, 40% and 41%, respectively, with better results for the top three most probable CODs. Performance generally improved with larger datasets. At the population level, the King-Lu method had the highest average cause-specific mortality fraction accuracy across all five datasets (91%), followed by InterVA-4 (72% across three datasets), open-source random forest (71%) and open-source tariff method (54%). Conclusions: On an individual level, no single method was able to replicate the physician assignment of COD more than about half the time. At the population level, the King-Lu method was the best method to estimate cause-specific mortality fractions, though it does not assign individual CODs. Future testing should focus on combining different computer-coded verbal autopsy tools, paired with PCVA strengths. This includes using open-source tools applied to larger and varied datasets (especially those including a random sample of deaths drawn from the population), so as to establish the performance for age- and sex-specific CODsItem How to set about a research project(1986) Cleaton-Jones, P.Item Cemento-enamel junction variability within the mouth(1988) Grossman, E. S.; Hargreaves, J. A.Item Writing a research report, dissertation or thesis(1986) Cleaton-Jones, P.Item Seal development and composition at amalgam-ceramic interfaces after NaCl and Na2S storage(1987) Jodaikin, A.; Grossman, E. S.; Witcomb, M. J.Item Base solubility and marginal sealing in amalgam restored teeth(1991) Grossman, E. S.; Witcomb, M. J.; Matejka, J. M.Item Social class and dental caries in 11-12-year-old South African schoolchildren(1989) Cleaton-Jones, P.; Hargreaves, J. A.; Williams, S. D. L.; et al.The objective of this study was to examine effects of social class on dental caries in five African populations. Definitions of social class that could be used for the different ethnic groups are outlined. A total of 1 154 children from rural black, urban black, urban Indian, urban coloured and urban white groups were clinically examined and classified into social class by parental occupations. Within group comparisons showed no statistically significant differences in DMFT or DMFS scores by social class. Comparison of the urban white children to a similar group in South Wales showed slightly lower caries in South African children of similar social class. The complexity of the different ethnic groups in South Africa, in respect of social classification, is difficult to assess for comparison with social systems in developed countries. It is recommended that an appropriate social classification be developed for South Africa ’s developed/developing population mixture. Also as we enter the 1990’s sound baseline caries data need to be collected for longitudinal evaluation of changes in the disease patternItem Failure at the dental restorative-etched enamel interface(1973) Retief, D. H.