Browsing by Author "Smith, Peter"

Now showing 1 - 4 of 4
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    HPTN 071 (PopART) : a cluster-randomized trial of the population impact of an HIV combination prevention intervention including universal testing and treatment : mathematical model
    (PLoS, 2014-01-15) Cori, Anne; Ayles, Helen; Beyers, Nulda; Schaap, Ab; Floyd, Sian; Sabapathy, Kalpana; Eaton, Jeffrey W.; Hauck, Katharina; Smith, Peter; Griffith, Sam; Moore, Ayana; Donnell, Deborah; Vermund, Sten H.; Fidler, Sarah; Hayes, Richard; Fraser, Christophe
    Background: The HPTN 052 trial confirmed that antiretroviral therapy (ART) can nearly eliminate HIV transmission from successfully treated HIV-infected individuals within couples. Here, we present the mathematical modeling used to inform the design and monitoring of a new trial aiming to test whether widespread provision of ART is feasible and can substantially reduce population-level HIV incidence. Methods and Findings: The HPTN 071 (PopART) trial is a three-arm cluster-randomized trial of 21 large population clusters in Zambia and South Africa, starting in 2013. A combination prevention package including home-based voluntary testing and counseling, and ART for HIV positive individuals, will be delivered in arms A and B, with ART offered universally in arm A and according to national guidelines in arm B. Arm C will be the control arm. The primary endpoint is the cumulative three-year HIV incidence. We developed a mathematical model of heterosexual HIV transmission, informed by recent data on HIV-1 natural history. We focused on realistically modeling the intervention package. Parameters were calibrated to data previously collected in these communities and national surveillance data. We predict that, if targets are reached, HIV incidence over three years will drop by >60% in arm A and >25% in arm B, relative to arm C. The considerable uncertainty in the predicted reduction in incidence justifies the need for a trial. The main drivers of this uncertainty are possible community-level behavioral changes associated with the intervention, uptake of testing and treatment, as well as ART retention and adherence. Conclusions: The HPTN 071 (PopART) trial intervention could reduce HIV population-level incidence by >60% over three years. This intervention could serve as a paradigm for national or supra-national implementation. Our analysis highlights the role mathematical modeling can play in trial development and monitoring, and more widely in evaluating the impact of treatment as prevention.
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    Intellectual disability rights and inclusive citizenship in South Africa : what can a scoping review tell us?
    (AOSIS, 2018) Capri, Charlotte; Abrahams, Lameze; McKenzie, Judith; Coetzee, Ockert; Mkabile, Siyabulela; Saptouw, Emanuel; Hooper, Andrew; Smith, Peter; Adnams, Collen; Swartz, Leslie
    Background: Intellectual disability (ID) is the most prevalent disability in the world. People with intellectual disability (PWID) frequently experience extreme violations of numerous human rights. Despite greater prevalence in South Africa than in high-income countries, most ID research currently comes from the Global North. This leaves us with few contextually sensitive studies to draw from to advance inclusive citizenship. Objectives: Our scoping review aims to investigate pertinent ID rights issues in South Africa, synthesise quantitative and qualitative studies, and provide a synopsis of available evidence on which to base future work. We aim to clarify key concepts, address gaps in the literature and identify opportunities for further research. Method: We followed strict eligibility criteria. Medical subject heading terms were entered into seven databases. Seven reviewers worked independently, two per paper. Quantitative and qualitative data extraction forms were designed. We followed Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines and registered a protocol. An inductive approach enabled a thematic analysis of selected studies. Results: By following PRISMA guidelines, 82 studies were assessed for eligibility of which 59 were included. Ten sub-themes were integrated into four main themes: the right not to be discriminated against, the right to psychological and bodily integrity, the right to accommodating services and challenges to rights implementation. Conclusion: People with intellectual disability face compound difficulties when trying to assert their constitutionally entitled rights. This ongoing project requires serious commitment and action. Statutory obligations to nurture every South African’s human rights naturally extend to PWID and their supporters who forge ahead in a disabling environment.
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    Nevirapine plasma concentrations in premature infants exposed to single-dose nevirapine for prevention of mother-to-child transmission of HIV-1
    (Health and Medical Publishing Group (HMPG), 2011-09) Mugabo, Pierre; Els, Ilse; Smith, Johan; Rabie, Helena; Smith, Peter; Mirochnick, Mark; Steyn, Wilhelm; Hall, David R.; Madsen, Richard; Cotton, Mark F.
    Background. No pharmacokinetic data exist for premature infants receiving single-dose nevirapine (sd NVP) for prevention of mother-to-child transmission (MTCT) of HIV. Aim. To describe NVP decay pharmacokinetics in two groups of premature infants - those whose mothers either received or did not receive NVP during labour. Methods. Infants less than 37 weeks' gestation were prospectively enrolled. Mothers received sd NVP during labour if time allowed. Infants received sd NVP and zidovudine. Blood was collected on specified days after birth and NVP concentrations were determined by liquid chromatography-mass spectrometry. Results. Data were obtained from 81 infants, 58 born to mothers who received sd NVP during labour (group I) and 23 to mothers who did not receive NVP (group II). Of the infants 29.6% were small for gestational age (SGA). Median (range) maximum concentration (Cmax), time to reach maximum concentration (Tmax), area under the plasma concentration-time curve (AUC) and halflife (T) were 1 438 (350-3 832) ng/ml, 25h50 (9h40-83h45), 174 134 (22 308-546 408) ng×h/ml and 59.0 (15.4-532.6) hours for group I and 1 535 (635-4 218) ng/ml, 17h35 (7h40-29h), 168 576 (20 268-476 712) ng×h/ml and 69.0 (22.12-172.3) hours for group II. For group II, the median (range) volume of distribution (Vd) and body clearance (Cl) were 1 702.6 (623.7-6 189.8) ml and 34.9 (6.2-163.8) ml/h. The AUC was higher (p=0.006) and Cl lower (p<0.0001) in SGA infants. Plasma concentrations exceeding 100 ng/ml were achieved over 8 days in 78% infants in group I and 70.0% in group II. The MTCT rate was 4.8%. Conclusion. Women in preterm labour often deliver with little advance warning. Our study suggests that NVP dosing of preterm infants as soon as possible after birth without maternal intrapartum dosing may be as effective as combined maternal and infant dosing.
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    Rifampin pharmacokinetics in children, with and without human immunodeficiency virus infection, hospitalized for the management of severe forms of tuberculosis
    (2009-04) Schaaf, H. Simon; Willemse, Marianne; Cilliers, Karien; Labadarios, Demetre; Maritz, Johannes Stephanus; Hussey, Gregory D.; McIlleron, Helen; Smith, Peter; Donald, Peter Roderick
    Background: Rifampin is a key drug in antituberculosis chemotherapy because it rapidly kills the majority of bacilli in tuberculosis lesions, prevents relapse and thus enables 6-month short-course chemotherapy. Little is known about the pharmacokinetics of rifampin in children. The objective of this study was to evaluate the pharmacokinetics of rifampin in children with tuberculosis, both human immunodeficiency virus type-1-infected and human immunodeficiency virus-uninfected. Methods: Fifty-four children, 21 human immunodeficiency virus-infected and 33 human immunodeficiency virus-uninfected, mean ages 3.73 and 4.05 years (P = 0.68), respectively, admitted to a tuberculosis hospital in Cape Town, South Africa with severe forms of tuberculosis were studied approximately 1 month and 4 months after commencing antituberculosis treatment. Blood specimens for analysis were drawn in the morning, 45 minutes, 1.5, 3.0, 4.0 and 6.0 hours after dosing. Rifampin concentrations were determined by liquid chromatography tandem mass spectrometry. For two sample comparisons of means, the Welch version of the t-test was used; associations between variables were examined by Pearson correlation and by multiple linear regression. Results: The children received a mean rifampin dosage of 9.61 mg/kg (6.47 to 15.58) body weight at 1 month and 9.63 mg/kg (4.63 to 17.8) at 4 months after commencing treatment administered as part of a fixed-dose formulation designed for paediatric use. The mean rifampin area under the curve 0 to 6 hours after dosing was 14.9 and 18.1 μg/hour/ml (P = 0.25) 1 month after starting treatment in human immunodeficiency virus-infected and human immunodeficiency virus-uninfected children, respectively, and 16.52 and 17.94 μg/hour/ml (P = 0.59) after 4 months of treatment. The mean calculated 2-hour rifampin concentrations in these human immunodeficiency virus-infected and human immunodeficiency virus-uninfected children were 3.9 and 4.8 μg/ml (P = 0.20) at 1 month after the start of treatment and 4.0 and 4.6 μg/ml (P = 0.33) after 4 months of treatment. These values are considerably less than the suggested lower limit for 2-hour rifampin concentrations in adults of 8.0 μg/ml and even 4 μg/ml Conclusion Both human immunodeficiency virus-infected and human immunodeficiency virus-uninfected children with tuberculosis have very low rifampin serum concentrations after receiving standard rifampin dosages similar to those used in adults. Pharmacokinetic studies of higher dosages of rifampin are urgently needed in children to assist in placing the dosage of rifampin used in childhood on a more scientific foundation.