| 61. |
- Byass, Peter, et al.
(författare)
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Malaria mortality in a hypoendemic area of North-Eastern South Africa : population-based surveillance from 1992 to 2013 reveals an increasing malaria burden
- 2015
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Ingår i: Tropical medicine & international health. - : Wiley-Blackwell. - 1360-2276 .- 1365-3156. ; 20:Suppl. 1, s. 128-128
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: Most of South Africa is malaria-free, but hypoendemic levels of transmission persist in lowveld areas in the north-east of the country, adjacent to Mozambique. Many families have links to relatives in Mozambique, where malaria transmission remains much higher, and cross-border travel is commonplace, although the Kruger National Park provides something of a depopulated buffer zone along the border. Malaria diagnosis and treatment is relatively easily available at public and private facilities in the endemic area.Methods: The Agincourt Health and Socio-Demographic Surveillance Site has monitored population health in a defined area within Mpumulanga Province, around 24.7°S, 31.2°E, since 1992. A circumscribed semi-rural area with a population ranging from approximately 60 000 in 1992 to 90 000 in 2013 was covered. All households were visited regularly to consistently record demographic and health data, including the documentation of deaths and their causes using verbal autopsy.Results: From 1992 to 2013 a total of 13 251 deaths were documented over 1.58 million person-years observed. Of that total mortality burden, 1.2% of deaths were ascribed to malaria. Half of the malaria deaths were among children aged under 15 years, with most of the remainder among working-age adults. Malaria deaths were strongly correlated with temperature and rainfall. The malaria mortality rate was over 50% higher during the last 5 years of the surveillance period, compared with earlier years. A huge HIV/AIDS epidemic that developed and receded in this population during the period of observation had no apparent effect on malaria mortality.Conclusions: This detailed longitudinal examination of malaria mortality showed that although malaria is a relatively minor cause of death in this population, it has become more common in recent years, and shows no sign of retreating despite rapid socioeconomic development. In addition to local relevance, these findings are important for understanding potential population burdens of hypoendemic malaria in other areas of sub-Saharan Africa as progress towards malaria control and elimination targets is realised.
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| 62. |
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| 63. |
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| 64. |
- Byass, Peter, et al.
(författare)
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Motherhood, migration and mortality in Dikgale : modelling life events among women in a rural South African community
- 2011
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Ingår i: Public Health. - London : Academic P.. - 0033-3506 .- 1476-5616. ; 125:5, s. 318-323
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Although particular types of life events in populations are often studied separately, this study investigated the joint effects of three major event types in South African women’s lives: motherhood, migration and mortality. Study design: Data were taken from a health and demographic surveillance site (HDSS) over an 11-year period, reflecting the entire population of a defined geographic area as an open cohort, in which individuals participated in regular longitudinal surveillance for health and demographic events. This HDSS is a member of the Indepth Network. Methods: Multivariate Poisson regression models were built for each of the three life event types, in which individual person-time observed out of the total possible 11-year period was used as a rate multiplier. These models were used to calculate adjusted incidence rate ratios for each factor. Results: In the 21,587 person–years observed for women aged 15–49 years, from 1996 to 2006, adjusted rate ratios for mortality and migration increased substantially over time, while motherhood remained fairly constant. Women who migrated were less likely to bear children; temporary migrants were at greater risk of dying, while permanent in-migrants had higher survival rates. Women who subsequently died were much less likely to bear children or migrate. Conclusions: The associations between motherhood, migration and mortality among these rural South African women were complex and dynamic. Extremely rapid increases in mortality over the period studied are presumed to reflect the effects of the human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) epidemic. Understanding these complex interactions between various life events at population level is crucial for effective public health planning and service delivery.
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| 65. |
- Byass, Peter, et al.
(författare)
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Moving from data on deaths to public health policy in Agincourt, South Africa : approaches to analysing and understanding verbal autopsy findings
- 2010
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Ingår i: PLoS Medicine. - : Public Library of Science. - 1549-1277 .- 1549-1676. ; 7:8, s. e1000325-
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Tidskriftsartikel (refereegranskat)abstract
- There were no differences between physician interpretation and probabilistic modelling that might have led to substantially different public health policy conclusions at the population level. Physician interpretation was more nuanced than the model, for example in identifying cancers at particular sites, but did not capture the uncertainty associated with individual cases. Probabilistic modelling was substantially cheaper and faster, and completely internally consistent. Both approaches characterised the rise of HIV-related mortality in this population during the period observed, and reached similar findings on other major causes of mortality. For many purposes probabilistic modelling appears to be the best available means of moving from data on deaths to public health actions. Please see later in the article for the Editors' Summary.
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| 66. |
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| 67. |
- Byass, Peter, et al.
(författare)
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Refining a probabilistic model for interpreting verbal autopsy data.
- 2006
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Ingår i: Scandinavian journal of public health. - : SAGE Publications. - 1403-4948 .- 1651-1905. ; 34:1, s. 26-31
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To build on the previously reported development of a Bayesian probabilistic model for interpreting verbal autopsy (VA) data, attempting to improve the model's performance in determining cause of death and to reassess it. Design: An expert group of clinicians, coming from a wide range geographically and in terms of specialization, was convened. Over a four-day period the content of the previous probabilistic model was reviewed in detail and adjusted as necessary to reflect the group consensus. The revised model was tested with the same 189 VA cases from Vietnam, assessed by two local clinicians, that were used to test the preliminary model. Results: The revised model contained a total of 104 indicators that could be derived from VA data and 34 possible causes of death. When applied to the 189 Vietnamese cases, 142 (75.1%) achieved concordance between the model's output and the previous clinical consensus. The remaining 47 cases (24.9%) were presented to a further independent clinician for reassessment. As a result, consensus between clinical reassessment and the model's output was achieved in 28 cases (14.8%); clinical reassessment and the original clinical opinion agreed in 8 cases (4.2%), and in the remaining 11 cases (5.8%) clinical reassessment, the model, and the original clinical opinion all differed. Thus overall the model was considered to have performed well in 170 cases (89.9%). Conclusions: This approach to interpreting VA data continues to show promise. The next steps will be to evaluate it against other sources of VA data. The expert group approach to determining the required probability base seems to have been a productive one in improving the performance of the model.
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| 68. |
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| 69. |
- Byass, Peter, et al.
(författare)
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Spatio-temporal clustering of mortality in Butajira HDSS, Ethiopia, from 1987 to 2008
- 2010
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Ingår i: Global Health Action. - : CoAction Publishing. - 1654-9716 .- 1654-9880. ; 3, s. 26-31
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Tidskriftsartikel (refereegranskat)abstract
- Background: Mortality in a population may be clustered in space and time for a variety of reasons, including geography, socio-economics, environment and demographics. Analysing mortality clusters can therefore reveal important insights into patterns and risks of mortality in a particular setting. Objective and design: To investigate the extent of spatio-temporal clustering of mortality in the Butajira District, Ethiopia, from 1987 to 2008. The Health and Demographic Surveillance System (HDSS) dataset recorded 10,696 deaths among 951,842 person-years of observation, with each death located by household, in which population time at risk was also recorded. The surveyed population increased from 28,614 in 1987 to 62,322 in 2008, in an area approximately 25 km in diameter. Spatio-temporal clustering analyses were conducted for overall mortality and by specific age groups, grouping the population into a 0.01° latitude-longitude grid. Results: A number of significantly high- and low-mortality clusters were identified at various times and places. Butajira town was characterised by significantly low mortality throughout the period. A previously documented major mortality crisis in 1998-1999, largely resulting from malaria and diarrhoea, dominated the clustering analysis. Other local high-mortality clusters, appreciably attributable to meningitis, malaria and diarrhoea, occurred in the earlier part of the period. In the later years, a more homogeneous distribution of mortality at lower rates was observed. Conclusions: Mortality was by no means randomly distributed in this community during the period of observation. The clustering analyses revealed a clear epidemiological transition, away from localised infectious epidemics, over a generation.
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| 70. |
- Byass, Peter, et al.
(författare)
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Strengthening standardised interpretation of verbal autopsy data : the new InterVA-4 tool
- 2012
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Ingår i: Global Health Action. - Järfälla, Sweden : CoAction Publishing. - 1654-9716 .- 1654-9880. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Background: Verbal autopsy (VA) is the only available approach for determining the cause of many deaths, where routine certification is not in place. Therefore, it is important to use standards and methods for VA that maximise efficiency, consistency and comparability. The World Health Organization (WHO) has led the development of the 2012 WHO VA instrument as a new standard, intended both as a research tool and for routine registration of deaths. Objective: A new public-domain probabilistic model for interpreting VA data, InterVA-4, is described, which builds on previous versions and is aligned with the 2012 WHO VA instrument. Design: The new model has been designed to use the VA input indicators defined in the 2012 WHO VA instrument and to deliver causes of death compatible with the International Classification of Diseases version 10 (ICD-10) categorised into 62 groups as defined in the 2012 WHO VA instrument. In addition, known shortcomings of previous InterVA models have been addressed in this revision, as well as integrating other work on maternal and perinatal deaths. Results: The InterVA-4 model is presented here to facilitate its widespread use and to enable further field evaluation to take place. Results from a demonstration dataset from Agincourt, South Africa, show continuity of interpretation between InterVA-3 and InterVA-4, as well as differences reflecting specific issues addressed in the design and development of InterVA-4. Conclusions: InterVA-4 is made freely available as a new standard model for interpreting VA data into causes of death. It can be used for determining cause of death both in research settings and for routine registration. Further validation opportunities will be explored. These developments in cause of death registration are likely to substantially increase the global coverage of cause-specific mortality data.
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