1,720,960 research outputs found
Predictive value of absolute CD4 cell count for disease progression in untreated HIV-1-infected children.
No full textOBJECTIVES: To describe the relationship between absolute CD4 cell count and the short-term risk of disease progression in HIV-1-infected children. DESIGN: A meta-analysis of individual longitudinal data on HIV-1-infected children enrolled in trials and cohort studies in Europe and the USA. METHODS: The risks of progression to death and AIDS (or death) within 12 months, in terms of age and the most recent CD4 cell count, were estimated using parametric survival models. The analysis was restricted to measurements before the start of antiretroviral therapy except zidovudine monotherapy. The values of the absolute CD4 cell count and percentage predicting selected levels of disease progression risk were determined from this and previous models. RESULTS: A total of 566 deaths was observed over 9128 person-years of follow-up, and 992 children progressed to AIDS or death over 7309 person-years of follow-up. In children older than 4 or 5 years, the estimated risk of disease progression increased sharply when the CD4 cell count fell below 200-300 cells/microl. As with other immunological markers, CD4 cell count was less prognostic in younger children. The CD4 cell count values predicting a 12-month risk of death of 2-5% and of AIDS of 5-10% were much more strongly influenced by age than equivalent CD4 cell percentage values. CONCLUSION: This study suggests it may be appropriate to extend CD4 cell count criteria for initiating antiretroviral therapy in HIV-1-infected adults to children as young as 4 or 5 years. Monitoring by CD4 cell count in younger children is problematical because age is a highly influential variable
Use of total lymphocyte count for informing when to start antiretroviral therapy in HIV-infected children: a meta-analysis of longitudinal data.
No full textBACKGROUND: Total lymphocyte count has been proposed as an alternative to the percentage of CD4+ T-cells to indicate when antiretroviral therapy should be started in children with HIV in resource-poor settings. We aimed to assess thresholds of total lymphocyte count at which antiretroviral therapy should be considered, and compared monitoring of total lymphocyte count with monitoring of CD4-cell percentage. METHODS: Longitudinal data on 3917 children with HIV infection were pooled from observational and randomised studies in Europe and the USA. The 12-month risks of death and AIDS by most recent total lymphocyte count and age were estimated by parametric survival models, based on measurements before antiretroviral therapy or during zidovudine monotherapy. Risks were derived and compared at thresholds of total lymphocyte count and CD4-cell percentage for starting antiretroviral therapy recommended in WHO 2003 guidelines. FINDINGS: Total lymphocyte count was a powerful predictor of the risk of disease progression despite a weak correlation with CD4-cell percentage (r=0.08-0.19 dependent on age). For children older than 2 years, the 12-month risk of death and AIDS increased sharply at values less than 1500-2000 cells per muL, with little trend at higher values. Younger children had higher risks and total lymphocyte count was less prognostic. Mortality risk was substantially higher at thresholds of total lymphocyte count recommended by WHO than at corresponding thresholds of CD4-cell percentage. When the markers were compared at the threshold values at which mortality risks were about equal, total lymphocyte count was as effective as CD4-cell percentage for identifying children before death, but resulted in an earlier start of antiretroviral therapy. INTERPRETATION: In this population, total lymphocyte count was a strong predictor of short-term disease progression, being only marginally less predictive than CD4-cell percentage. Confirmatory studies in resource-poor settings are needed to identify the most cost-effective markers to guide initiation of antiretroviral therapy
Current CD4 cell count and the short-term risk of AIDS and death before the availability of effective antiretroviral therapy in HIV-infected children and adults.
No full textBACKGROUND: Currently, there are no comparable estimates of the short-term risk of disease progression in the absence of effective antiretroviral therapy for human immunodeficiency virus (HIV)-infected adults and children. METHODS: A joint analysis of 2 large studies of children with vertically acquired HIV infection (the HIV Paediatric Prognostic Markers Collaborative Study) and adults with seroconversion (the CASCADE [Concerted Action on Sero-Conversion to AIDS and Death in Europe] collaboration) was conducted. Follow-up was censored at the end of 1995, before the introduction of combination antiretroviral therapy. The incidence rates of death and AIDS or death (AIDS/death) were estimated on the basis of age and current CD4 cell count. RESULTS: A total of 1260 deaths (over 20,500 person-years of follow-up) and 1894 initial AIDS events (over 17,200 person-years of follow-up) were observed among 6741 patients (3244 children [i.e., patients or = 5 years of age
Survival, virological and immunological outcomes of HIV-infected children accessing ART at South African primary health care clinics
No full textIncludes bibliographical references.South Africa faces the world’s largest pediatric HIV epidemic. Combination antiretroviral therapy (ART) is the only effective treatment for HIV virus suppression. Pediatric HIV care has traditionally been provided in academic research and tertiary care facilities, however efforts to improve ART availability for children are ongoing through decentralization. Tygerberg Hospital physicians with training in pediatric HIV management are providing care in seven community-based primary health care (PHC) clinics in the greater Cape Town region. ART initiation and ongoing ART management for those down-referred from tertiary and district level facilities are provided. The HIV-related outcomes of this cohort have yet to be reported
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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