Browsing by Author "Marston, Milly"

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    Age-Specific Mortality Patterns in HIV-Infected Individuals: A Comparative Analysis of African Community Study Data
    (Aids, 2007) Zaba, Basia; Marston, Milly; Crampin, Amelia C.; Isingo, Raphael; Biraro, Sam; Ba¨rnighausen, Till; Lopman, Ben; Lutalo, Tom; Glynn, Judith R.; Todd, Jim
    Describe age-specific mortality patterns of HIV-infected adults in African communities before introduction of HAART.Mortality data (deaths and person-years observed) for HIV-positive subjects aged 15–65 from six African community studies in five different countries were pooled, combining information from 1793 seroconverters and 8534 HIV positive when first tested. Age-specific mortality hazards were modelled using parametric regression based on the Weibull distribution, to investigate effects of sex, and site-specific measures of mean age at incidence, crude mortality rate of uninfected, and measures of epidemic maturity.The combined studies yielded a total of 31 777 person-years of observation for HIV-positive subjects, during which time 2602 deaths were recorded. Mortality rates rose almost linearly with age, from below 50/1000 at ages < 20 years, up to 150/1000 at 50 years +. There was no significant difference between men and women in level or age pattern of mortality. Weibull regression analysis suggested that intersite variation could be explained by HIV prevalence trend, and by the ratio of HIV proportional mortality to current HIV prevalence. A model representation was constructed with a common age pattern of mortality, but allowing the level to be adjusted by specifying HIV prevalence indicators.The linear age trend of mortality in HIV-infected populations was satisfactorily represented by a Weibull function providing a parametric model adaptable for representing different levels of HIV-related mortality. This model might be simpler to use in demographic projections of HIV-affected populations than models based on survival post-infection.
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    Data Resource Profile: Network for Analysing Longitudinal Population-based HIV/AIDS data on Africa (ALPHA Network)
    (International journal of epidemiology, 2016) Reniers, Georges; Lutalo, Tom; Wamukoya, Marylene; Urassa, Mark; Nakiyingi-Miiro, Jessica; Hosegood, Vicky; Wringe, Alison; Marston, Milly; Maquins, Sewe; Levira, Francis; Zaba, Basia
    The Network for Analysing Longitudinal Population-based HIV/AIDS data on Africa (ALPHA Network) was established in 2005 and aims to: (i) broaden the evidence base on HIV epidemiology for informing policy; (ii) strengthen analytical capacity for HIV research; and (iii) foster collaboration between study sites.1 All of the study sites participating in the ALPHA Network are independently managed and have their own scientific agendas and tailored research methodologies, but share a common interest in HIV epidemiology and its interactions with the socio-demographic characteristics of the populations they cover. The ALPHA Network study sites and their institutional affiliations are described in Table 1, and their geographical distribution is shown in Figure 1. Several of the ALPHA Network study sites have published site-specific profiles that contain more detail.2–10 Most of the ALPHA Network study sites are also members of the INDEPTH Network of demographic surveillance sites [http:// www.indepth-network.org/].
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    Effect of HIV infection on pregnancy-related mortality in sub-Saharan Africa: secondary analyses of pooled community based data from the network for Analysing Longitudinal Population-based HIV/AIDS data on Africa (ALPHA)
    (The Lancet, 2013) Zaba, Basia; Calvert, Clara; Marston, Milly; Isingo, Raphael; Nakiyingi-Miiro, Jessica; Lutalo, Tom; Crampin, Amelia; Robertson, Laura; Herbst, Kobus; Ronsmans, Carine
    Model-based estimates of the global proportions of maternal deaths that are in HIV-infected women range from 7% to 21%, and the eff ects of HIV on the risk of maternal death is highly uncertain. We used longitudinal data from the Analysing Longitudinal Population-based HIV/AIDS data on Africa (ALPHA) network to estimate the excess mortality associated with HIV during pregnancy and the post-partum period in sub-Saharan Africa. Methods The ALPHA network pooled data gathered between June, 1989 and April, 2012 in six community-based studies in eastern and southern Africa with HIV serological surveillance and verbal-autopsy reporting. Deaths occurring during pregnancy and up to 42 days post partum were defi ned as pregnancy related. Pregnant or postpartum person-years were calculated for HIV-infected and HIV-uninfected women, and HIV-infected to HIVuninfected mortality rate ratios and HIV-attributable rates were compared between pregnant or post-partum women and women who were not pregnant or post partum. Findings 138 074 women aged 15–49 years contributed 636 213 person-years of observation. 49 568 women had 86 963 pregnancies. 6760 of these women died, 235 of them during pregnancy or the post-partum period. Mean prevalence of HIV infection across all person-years in the pooled data was 17·2% (95% CI 17·0–17·3), but 60 of 118 (50·8%) of the women of known HIV status who died during pregnancy or post partum were HIV infected. The mortality rate ratio of HIV-infected to HIV-uninfected women was 20·5 (18·9–22·4) in women who were not pregnant or post partum and 8·2 (5·7–11·8) in pregnant or post-partum women. Excess mortality attributable to HIV was 51·8 (47·8–53·8) per 1000 person-years in women who were not pregnant or post partum and 11·8 (8·4–15·3) per 1000 person-years in pregnant or post-partum women. Interpretation HIV-infected pregnant or post-partum women had around eight times higher mortality than did their HIV-uninfected counterparts. On the basis of this estimate, we predict that roughly 24% of deaths in pregnant or post-partum women are attributable to HIV in sub-Saharan Africa, suggesting that safe motherhood programmes should pay special attention to the needs of HIV-infected pregnant or post-partum women.
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    Estimating ‘net’ HIV-related Mortality and the Importance of Background Mortality Rates
    (AIDS, 2007) Marston, Milly; Todd, Jim; Glynn, Judith R.; Nelson, Kenrad E.; Rangsin, Ram; Lutalo, Tom; Urassa, Mark; Biraro, Sam; Paal, Lieve Van der; Sonnenberg, Pam; Żaba, Basia
    To estimate mortality directly attributable to HIV in HIV-infected adults in low and middle income countries and discuss appropriate methodology.Illustrative analysis of pooled data from six studies across sub-Saharan Africa and Thailand with data on individuals with known dates of seroconversion to HIV.Five of the studies also had data from HIV-negative subjects and one had verbal autopsies. Data for HIV-negative cohorts were weighted by the initial age and sex distribution of the seroconverters. Using the survival of the HIV-negative group to represent the background mortality, net survival from HIV was calculated for the seroconverters using competing risk methods. Mortality from all causes and ‘net’ mortality were modelled using piecewise exponential regression. Alternative approaches are explored in the dataset without information on mortality of uninfected individuals.The overall effect of the net mortality adjustment was to increase survivorship proportionately by 2 to 5% at 6 years post-infection. The increase ranged from 2% at ages 15–24 to 22% in those 55 and over. Mortality rate ratios between sites were similar to corresponding ratios for all-cause mortality.Differences between HIV mortality in different populations and age groups are not explained by differences in background mortality, although this does appear to contribute to the excess at older ages. In the absence of data from uninfected individuals in the same population, model life tables can be used to calculate background rates.