67 research outputs found
Calibrating models in economic evaluation: A comparison of alternative measures of goodness of fit, parameter search strategies and convergence criteria
No full textBackgroundThe importance of assessing the accuracy of health economic decision models is widely recognized. Many applied decision models (implicitly) assume that the process of identifying relevant values for a model's input parameters is sufficient to prove the model's accuracy. The selection of infeasible combinations of input parameter values is most likely in the context of probabilistic sensitivity analysis (PSA), where parameter values are drawn from independently specified probability distributions for each model parameter. Model calibration involves the identification of input parameter values that produce model output parameters that best predict observed data.MethodsAn empirical comparison of three key calibration issues is presented: the applied measure of goodness of fit (GOF); the search strategy for selecting sets of input parameter values; and the convergence criteria for determining acceptable GOF. The comparisons are presented in the context of probabilistic calibration, a widely applicable approach to calibration that can be easily integrated with PSA. The appendix provides a user's guide to probabilistic calibration, with the reader invited to download the Microsoft® Excel-based model reported in this article.ResultsThe calibrated models consistently provided higher mean estimates of the models' output parameter, illustrating the potential gain in accuracy derived from calibrating decision models. Model uncertainty was also reduced. The chi-squared GOF measure differentiated between the accuracy of different parameter sets to a far greater degree than the likelihood GOF measure. The guided search strategy produced higher mean estimates of the models' output parameter, as well as a narrower range of predicted output values, which may reflect greater precision in the identification of candidate parameter sets or more limited coverage of the parameter space. The broader convergence threshold resulted in lower mean estimates of the models' output, and slightly wider ranges, which were closer to the outputs associated with the non-calibrated approach.ConclusionsProbabilistic calibration provides a broadly applicable method that will improve the relevance of health economic decision models, and simultaneously reduce model uncertainty. The analyses reported in this paper inform the more efficient and accurate application of calibration methods for health economic decision models.Jonathan Karnon, Tazio Vann
Economic modelling assessment of cervical cancer screening and HPV vaccination in Brazil
No full textMore than 85% of the global burden of cervical cancer occurs in developing countries, where it
is the second most common cancer among women. In Brazil alone, a total of 17,500 new cases
and 3,300 deaths of cervical cancer are expected in 2012. Despite the investments in cytologybased
screening in the country, the reduction of cervical cancer incidence has been less than
expected. The aim of this thesis was to investigate the cost-effectiveness of alternative cervical
cancer screening and HPV vaccination strategies in Brazil. This was achieved by focusing on
three specific objectives: 1) To evaluate the cost-effectiveness of cervical cancer screening
strategies for women presenting equivocal cytological results, 2) To evaluate the costeffectiveness
of cervical cancer screening strategies for HIV-infected women, 3) To evaluate
the cost-effectiveness of HPVvaccination for pre-adolescent women. An additional objective
was to review and provide guidance on the use of model calibration methods in economic
modelling assessments,as they are particularly important in screening and vaccination studies.
The first empirical analysis found that HPV triage for women above 30 years-old presenting
equivocal cytology results was likely to be very cost-effective. The second empirical analysis
found that to screen HIV-infected women with HPVtesting followed by cytology annually was
also likely to be very cost-effective. The third empirical analysis demonstrated that adding the
quadrivalent vaccination of pre-adolescent girls to the current efforts to control cervical cancer
in Brazil was very cost-effective for most of the scenarios analyzed. The vaccine was even cost
saving when considering low coverage and cost of vaccination. This thesis presents findings
that will inform cervical cancer screening and HPV vaccination policies in middle-income
countries like Brazil and also provides guidance to help improve the standards of model
calibration approaches used in cost-effectiveness analysis
International scientific collaboration in HIV and HPV: a network analysis
No full textResearch endeavours require the collaborative effort of an increasing number of individuals. International scientific collaborations are particularly important for HIV and HPV co-infection studies, since the burden of disease is rising in developing countries, but most experts and research funds are found in developed countries, where the prevalence of HIV is low. The objective of our study was to investigate patterns of international scientific collaboration in HIV and HPV research using social network analysis. Through a systematic review of the literature, we obtained epidemiological data, as well as data on countries and authors involved in co-infection studies. The collaboration network was analysed in respect to the following: centrality, density, modularity, connected components, distance, clustering and spectral clustering. We observed that for many low- and middle-income countries there were no epidemiological estimates of HPV infection of the cervix among HIV-infected individuals. Most studies found only involved researchers from the same country (64%). Studies derived from international collaborations including high-income countries and either low- or middle-income countries had on average three times larger sample sizes than those including only high-income countries or low-income countries. The high global clustering coefficient (0.9) coupled with a short average distance between researchers (4.34) suggests a “small-world phenomenon.” Researchers from high-income countries seem to have higher degree centrality and tend to cluster together in densely connected communities. We found a large well-connected community, which encompasses 70% of researchers, and 49 other small isolated communities. Our findings suggest that in the field of HIV and HPV, there seems to be both room and incentives for researchers to engage in collaborations between countries of different income-level. Through international collaboration resources available to researchers in high-income countries can be efficiently used to enroll more participants in low- and middle-income countries.<br/
Economic evaluation of linezolid versus vancomycin in mechanical ventilation-associated nosocomial pneumonia caused by methicillin-resistant Staphylococcus aureus
No full textCervical cancer screening: Barriers to access and potential solutions for Nigeria
No full textIn developed countries, giant strides have been made in reducing mortality due to cervical cancer. The success recorded has been largely attributed to effective screening programmes. In contrast, the burden and mortality due to this disease is rising in developing countries. Access to screening services remains a major challenge for the majority of the population at risk. This paper reviews the current demand-side barriers to cervical cancer screening inNigeriaand identifies potential solutions. Using academic databases and grey literature, a review was carried out to identify current screening modalities, barriers to access, and potential solutions. The current innovative method for control is early detection and treatment using “See and Treat” which involves visual inspection of the cervix with acetic acid (VIA) and cryotherapy. Lack of awareness, cost, and availability were identified as major barriers to access. Potential solutions feasible in the Nigerian context were categorized as financial and non-financial. The potential financial interventions include voucher schemes, conditional cash transfers, health equity, community loan funds, and prepayment mechanisms. Potential non-financial interventions that would be useful include raising awareness via health education and counseling, community participation, community based interventions, and pre-payment mechanisms
Scientific diaspora from an emerging economy: inclination to return and connections to the home country
No full textTo better inform policies on talent flow in emerging countries, this article evaluates the determinants of return migration among Brazilian researchers and post-graduate students in Britain, as well as, their personal and professional ties to Brazil. Most participants were inclined to engage in return migration (67%). The perception of the job market and career values were associated to their willingness to return, particularly, to receive job advertisements from EU institutions (OR=0.32, p=0.03) and to identify high income as professional success (OR=0.35, p=0.05). Personal ties to Brazil were both more frequent and influential in return migration plans than professional ties. Only 19% of participants were actively involved in research partnerships between the two countries. A series of policy implications were discussed at the institutional, national and international level. Evidence-based policies to engage with the scientific diaspora and to foster international partnerships are both critical to maximize social benefits and to secure equitable development worldwid
Scientific Diaspora from an Emerging Economy: Inclination to Return and Connections to the Home Country
No full textTo better inform policies on talent flow in emerging countries, this article evaluates the determinants of return migration among Brazilian researchers and post-graduate students in Britain, as well as, their personal and professional ties to Brazil. Most participants were inclined to engage in return migration (67%). The perception of the job market and career values were associated to their willingness to return, particularly, to receive job advertisements from EU institutions (OR=0.32, p=0.03) and to identify high income as professional success (OR=0.35, p=0.05). Personal ties to Brazil were both more frequent and influential in return migration plans than professional ties. Only 19% of participants were actively involved in research partnerships between the two countries. A series of policy implications were discussed at the institutional, national and international level. Evidence-based policies to engage with the scientific diaspora and to foster international partnerships are both critical to maximize social benefits and to secure equitable development worldwide. Keywords: scientific diaspora, international mobility of researchers, brain drain, migration, international research partnerships
Biografie
No full textLe biografie ricostruiscono il contesto storico e percorso professionale dei principali fotografi italiani e/o attivi in Italia nella seconda metà del XX secolo. Il lavoro di ricerca storica svolto per la realizzazione delle biografie ha permesso di definire l'identità di fotografi come Joseph Leombruno e Jack Bodi, fotografi di nazionalità statunitense attivi in Italia dalla metà degli anni Cinquanta ed erroneamente dati come una coppia (marito e moglie) di fotografi italiani. Il contributo documenta il lavoro dei seguenti fotografi: Maria Vittoria Backhaus, Vanessa Beecroft, Manfredi Bellati, Flavio Bonetti, Fiorenzo Borghi, Vanni Burkhart, Sergio Caminata, Silvia Camporesi, Antonio Capa, Max Cardelli, Alfa Castaldi, Elisabetta Catalano, Loris Cecchini, Davide Cernuschi, Antonio Cesano, Gianmarco Chieregato, Manlio Conte, Diego D’Alessandro, Pasquale De Antonis, Mario De Biasi, Gianni Della Valle, Martina Della Valle, Alberto Dell’Orto, Giovanni Maria Fadigati, Aldo Fallai, Pierpaolo Ferrari, Fabrizio Ferri, Angelo Frontoni, Diego Fuga, Stefano Galuzzi, Andrea Gandini, Giovanni Gastel, Piero Gemelli, Arturo Ghergo, Fabrizio Gianni, Marco Glaviano, Renato Grignaschi, Elsa Haertter, Bob Krieger, Marco La Conte, Leombruno-Bodi, Armin Linke, Giovanni Lunardi, Elio Luxardo, Tiziano Magni, Rennio Maifredi, Toni Meneguzzo, Johnny Moncada, Stefano Moro, Antonia Mulas, Ugo Mulas, Occhiomagico, Carlo Orsi, Stefania Paparelli, Federico Patellani, Manuela Pavesi, Publifoto, Roberto Quagli, Regina Relang, Alberto Rizzo, Willy Rizzo, Elsa Robiola, Paolo Roversi, Franco Rubartelli, Mario Santana, Laura Sciacovelli, Ferdinando Scianna, Fortunato Scrimali, Tazio Secchiaroli, Elisabetta Senesi, Mario Sorrenti, Andrea Spotorno, Lina Tenca, Toni Thorimbert, Alberta Tiburzi, Riccardo Tinelli, Oliviero Toscani, Paolo Ventura, Francesco Vezzoli
Biographies
No full textLe biografie ricostruiscono il contesto storico e percorso professionale dei principali fotografi italiani e/o attivi in Italia nella seconda metà del XX secolo. Il lavoro di ricerca storica svolto per la realizzazione delle biografie ha permesso di definire l'identità di fotografi come Joseph Leombruno e Jack Bodi, fotografi di nazionalità statunitense attivi in Italia dalla metà degli anni Cinquanta ed erroneamente dati come una coppia (marito e moglie) di fotografi italiani. Il contributo documenta il lavoro dei seguenti fotografi: Maria Vittoria Backhaus, Vanessa Beecroft, Manfredi Bellati, Flavio Bonetti, Fiorenzo Borghi, Vanni Burkhart, Sergio Caminata, Silvia Camporesi, Antonio Capa, Max Cardelli, Alfa Castaldi, Elisabetta Catalano, Loris Cecchini, Davide Cernuschi, Antonio Cesano, Gianmarco Chieregato, Manlio Conte, Diego D’Alessandro, Pasquale De Antonis, Mario De Biasi, Gianni Della Valle, Martina Della Valle, Alberto Dell’Orto, Giovanni Maria Fadigati, Aldo Fallai, Pierpaolo Ferrari, Fabrizio Ferri, Angelo Frontoni, Diego Fuga, Stefano Galuzzi, Andrea Gandini, Giovanni Gastel, Piero Gemelli, Arturo Ghergo, Fabrizio Gianni, Marco Glaviano, Renato Grignaschi, Elsa Haertter, Bob Krieger, Marco La Conte, Leombruno-Bodi, Armin Linke, Giovanni Lunardi, Elio Luxardo, Tiziano Magni, Rennio Maifredi, Toni Meneguzzo, Johnny Moncada, Stefano Moro, Antonia Mulas, Ugo Mulas, Occhiomagico, Carlo Orsi, Stefania Paparelli, Federico Patellani, Manuela Pavesi, Publifoto, Roberto Quagli, Regina Relang, Alberto Rizzo, Willy Rizzo, Elsa Robiola, Paolo Roversi, Franco Rubartelli, Mario Santana, Laura Sciacovelli, Ferdinando Scianna, Fortunato Scrimali, Tazio Secchiaroli, Elisabetta Senesi, Mario Sorrenti, Andrea Spotorno, Lina Tenca, Toni Thorimbert, Alberta Tiburzi, Riccardo Tinelli, Oliviero Toscani, Paolo Ventura, Francesco Vezzoli
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