The diffusion dynamics of choice: From durable goods markets to fashion first names

Goods, styles, ideologies are adopted by society through various mechanisms. In particular, adoption driven by innovation is extensively studied by marketing economics. Mathematical models are currently used to forecast the sales of innovative goods. Inspired by the theory of diffusion processes developed for marketing economics, we propose, for the first time, a predictive framework for the mechanism of fashion, which we apply to first names. Analyses of French, Dutch and US national databases validate our modelling approach for thousands of first names, covering, on average, more than 50% of the yearly incidence in each database. In these cases, it is thus possible to forecast how popular the first names will become and when they will run out of fashion. Furthermore, we uncover a clear distinction between popularity and fashion: less popular names, typically not included in studies of fashion, may be driven by fashion, as well.Comment: 11 pages, 1 table, 2 figures, 4 pages of supporting informatio

Towards standardized definitions for monitoring the continuum of HIV care in Europe

International audienceThe continuum of HIV care is a simple conceptual framework for monitoring HIV programmes, comprising a series of stages that people living with HIV (PLHIV) pass through to access antiretroviral treatment (ART) and achieve viral suppression [1,2]. Individual benefits of suppression include reduced risk of morbidity and mortality. At the population level, viral suppression reduces the risk of onward transmission and enables epidemic containment [3]. Transmission risk may be further reduced by lowering the number of undiagnosed PLHIV [4,5]. Complete continua are, therefore, constructed beginning with the total number of PLHIV in a given population and ending with the number virally suppressed. Intervening stages have included the numbers diagnosed, linked to HIV care, retained in care, eligible for ART, on ART and adhering to ART. Although people can move between stages, the continuum is typically conceptualized as a ‘snapshot’ at one time-point

HIV testing within general practices in Europe : A mixed-methods systematic review

Funding Information: This work was supported by IWT (Belgium) and the ANRS (France) through the framework of HIVERA JTC 2014. Publisher Copyright: © 2018 The Author(s).Background: Late diagnosis of HIV infection remains a key challenge in Europe. It is acknowledged that general practitioners (GPs) may contribute greatly to early case finding, yet there is evidence that many diagnostic opportunities are being missed. To further promote HIV testing in primary care and to increase the utility of available research, the existing evidence has been synthesised in a systematic review adhering to the PRISMA guidelines. Methods: The databases PubMed, Scopus and Embase were searched for the period 2006-2017. Two authors judged independently on the eligibility of studies. Through a mixed-methods systematic review of 29 studies, we provide a description of HIV testing in general practices in Europe, including barriers and facilitators. Results: The findings of the study show that although various approaches to target patients are used by GPs, most tests are still carried out based on the patient's request. Several barriers obstruct HIV testing in general practice. Included are a lack of communication skills on sexual health, lack of knowledge about HIV testing recommendations and epidemic specificities, difficulties with using the complete list of clinical HIV indicator diseases and lack of experience in delivering and communicating test results. The findings also suggest that the provision of specific training, practical tools and promotion programmes has an impact on the testing performance of GPs. Conclusions: GPs could have an increased role in provider-initiated HIV-testing for early case finding. To achieve this objective, solutions to the reported barriers should be identified and testing criteria adapted to primary healthcare defined. Providing guidance and training to better identify priority groups for HIV testing, as well as information on the HIV epidemic's characteristics, will be fundamental to increasing awareness and testing by GPs.publishersversionPeer reviewe

The Human Immunodeficiency Virus Continuum of Care in European Union Countries in 2013: Data and Challenges.

BACKGROUND.: The Joint United Nations Programme on HIV/AIDS (UNAIDS) has set a "90-90-90" target to curb the human immunodeficiency virus (HIV) epidemic by 2020, but methods used to assess whether countries have reached this target are not standardized, hindering comparisons. METHODS.: Through a collaboration formed by the European Centre for Disease Prevention and Control (ECDC) with European HIV cohorts and surveillance agencies, we constructed a standardized, 4-stage continuum of HIV care for 11 European Union countries for 2013. Stages were defined as (1) number of people living with HIV in the country by end of 2013; (2) proportion of stage 1 ever diagnosed; (3) proportion of stage 2 that ever initiated ART; and (4) proportion of stage 3 who became virally suppressed (≤200 copies/mL). Case surveillance data were used primarily to derive stages 1 (using back-calculation models) and 2, and cohort data for stages 3 and 4. RESULTS.: In 2013, 674500 people in the 11 countries were estimated to be living with HIV, ranging from 5500 to 153400 in each country. Overall HIV prevalence was 0.22% (range, 0.09%-0.36%). Overall proportions of each previous stage were 84% diagnosed, 84% on ART, and 85% virally suppressed (60% of people living with HIV). Two countries achieved ≥90% for all stages, and more than half had reached ≥90% for at least 1 stage. CONCLUSIONS.: European Union countries are nearing the 90-90-90 target. Reducing the proportion undiagnosed remains the greatest barrier to achieving this target, suggesting that further efforts are needed to improve HIV testing rates. Standardizing methods to derive comparable continuums of care remains a challenge

Brief Report: Per Sex-Act Risk of HIV Transmission Under Antiretroviral Treatment: A Data-Driven Approach

International audienceBackground: Before the completion of HPTN 052, PARTNER, and Opposites Attract studies, data were lacking to directly estimate HIV transmission risk under effective combined antiretroviral treatment (cART). Rather, estimates were obtained by extrapolating a dose-response relationship between viral load and risk of HIV transmission, observed among untreated individuals, to treated individuals. Presently, data have accumulated from 9 clinical studies for a direct validation of this extrapolation.Methods: Using estimates of per sex-act risk of HIV transmission on effective cART obtained by extrapolation, sexual behavior data, and a simple mathematical model, we estimated the number of seroconversions that should have been observed in HIV-serodiscordant couples where the HIV-positive partner was on cART across the 9 studies. We compared this with the number of seroconversions actually observed. Next, we directly estimated the risk of HIV transmission on effective cART, using Bayesian statistics to combine all available data.Results: We found that at least 4.7 (uncertainty bounds: 1.7-12.6) and 35.1 (uncertainty bounds: 13.2-92.0) seroconversions should have been observed among, respectively, heterosexual and men who have sex with men (MSM) serodiscordant couples. This is not validated by observations across the studies, which reported at most 1 seroconversion among heterosexual couples and 0 for MSM. Combining all available data, we found that the maximum per sex-act risk of HIV transmission under effective cART is 3.9:100,000 for heterosexuals and 4.4:100,000 for MSM.Conclusions: Data have accumulated to render obsolete estimates of the risk of HIV transmission on cART obtained by extrapolation. Direct estimates are substantially lower and should be used in practice

Modélisation de l'épidémie d'encéphalopathie spongiforme bovine en France et implications pour le consommateur (une approche par rétrocalcul)

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

The unrecognised French BSE epidemic

In France, implementation of systematic screening programs in 2000, as a complement to the mandatory reporting of animals with clinical signs of BSE (passive surveillance), revealed certain limitations of the mandatory system. Indeed, systematic screening showed that some BSE cases were not detected by the clinical surveillance system, implying considerable BSE case under-reporting throughout the epidemic. As the most likely explanation for variant Creutzfeldt-Jakob disease (vCJD) is exposure to the aetiologic agent of BSE, it is essential to reconstruct the French BSE epidemic pattern accounting for this under-reporting. We estimated age- and year-specific incidence rates of BSE by using a back-calculation method. This approach relies on the principle that the number of clinical BSE cases is the consequence of the number of BSE-infected animals after a known incubation time, defined as the time between infection and clinical onset. We generalized this model to take into account epidemiological characteristics of BSE, such as French cattle mortality, BSE case reporting probability, and age-dependent susceptibility and/or exposure to the BSE agent. We confirmed that the average BSE incubation period is five years and that the peak risk of bovine infection occurs between 6 and 12 months of age. The results also showed that the proportion of underreporting is the most influential parameter in the model, and that BSE was substantially underreported until rapid tests were introduced. Indeed, only 103 BSE cases were detected by passive surveillance up to June 2000, while we estimated that there was 301 200 (95% confidence interval (CI) [27 600–837 600]) cattle infected by the BSE agent. Despite uncertainty over the beginning of the epidemic, we showed that the French BSE epidemic in the late 1980s was completely undetected, and only the second wave, after 1990, was observed