Introduction. Sunbeds emit ultraviolet (UV) radiation to produce a cosmetic tan and are classified by the World Health Organization as first-group carcinogens: they have been significantly associated with increased risk of melanoma and non-melanoma skin cancer. Despite this, controversies still exist: since sunbeds are able to increase serum vitamin D, the sunbed industry relentlessly tries to promote them as a safe therapeutic measure; and some authors have recently expressed scepticism about the carcinogenicity of sunbeds. Moreover, differences between European countries in terms of prevalence of use have not been extensively studied and a better understanding of the determinants of use in Europe is much needed. Similarly, the association of sunbed use with skin cancer risk factors is poorly understood. Euromelanoma is a skin cancer prevention campaign conducted all over Europe. It offers a once-a-year screening during which participants’ data, including sunbed use and phenotype, are collected via questionnaires.Objectives. To thoroughly describe prevalence, determinants, and risks associated with sunbed use in Europe. To this aim we performed literature reviews (3 publications) and an extensive analysis of the Euromelanoma database, which included data from 30 European countries (2 publications).Methods. For the 3 reviews we searched the most used databases for any literature published in English using all pertinent keywords. As for the 2 Euromelanoma studies, participants filled in questionnaires about demographics and risk factors, including type/duration of sunbed use. Multivariate analyses adjusted for all confounders were employed to assess factors independently associated with sunbed use in each country.Results. Our reviews showed that: (i) European sunbed users are typically young women, sun seekers, and smokers, mostly from northern countries, going to tanning studios with aesthetic motives, although exceptions exist; (ii) in case of vitamin D deficiency, the risk/benefit ratio is clearly in favour of vitamin D supplementation instead of sunbed use; (iii) all epidemiological criteria for causality apply to the relationship between sunbed use and melanoma. The Euromelanoma studies included 227,888 individuals (67.4% females, median age 44) from 30 countries. Overall prevalence of sunbed ever use was 10.6%. Prevalence was higher in northern, sun-deprived countries, with the exception of Italy and Spain. Females displayed higher prevalence than males in all countries. Geographic particularities were found in four regions: Iberian (prevalence ten times higher in Spain than Portugal), Balkan (prevalence disproportionately higher among women), Baltic (highest prevalence among young adults), and Scandinavian (highest prevalence among adolescents). Ever sunbed use was independently associated with nevus count >50 [summary odds ratio (SOR)=1.05 (1.01-1.10)], atypical nevi [SOR=1.04 (1.00-1.09)], lentigines [SOR=1.16 (1.04-1.29)], and suspicion of melanoma [SOR=1.13 (1.00-1.27)]. Conclusions. After a thorough literature revision, we concluded that the debate over whether sunbed use contributes to melanoma should be definitively closed and that sunbeds are not a safe option to increase vitamin D levels. The Euromelanoma analysis on sunbeds and skin cancer risk factors suggests that avoidance/discontinuation of sunbed use should always be encouraged, especially, but not exclusively, for individuals with high-risk phenotypes. The data about prevalence/determinants of sunbed use have public health relevance for future, tailored interventions aimed at reducing indoor tanning in Europe. / Introduction. Les bancs solaires émettent des radiations ultraviolettes (UV) pour induire un bronzage cosmétique. Ils sont classés par l’Organisation Mondiale de la Santé comme carcinogènes de premier groupe: ils sont significativement associés à un risque accru de mélanome et de cancers cutanés non-mélanome. Malgré ça, des controverses existent toujours :comme leur utilisation permet d’accroitre le taux sérique de vitamine D, l’industrie du bronzage artificiel n’a cessé de les promouvoir comme thérapeutique sans danger et certains auteurs ont récemment mis en doute la carcinogénicité des bancs solaires. Par ailleurs, les différences entre les pays européens en terme de prévalence et de facteurs déterminant l’utilisation des bancs solaires n’ont pas été clairement étudiées. De la même façon, la relation entre bronzage artificiel et facteurs de risque de cancérisation cutanée reste floue. Euromelanoma est une campagne pan-européenne annuelle de prévention de cancers cutanés, où des questionnaires récoltent les données des participants (usage des bancs solaires, phénotype et informations cliniques inclus).Objectifs. Décrire de manière approfondie la prévalence, les déterminants et les risques associés à l’utilisation des bancs solaires en Europe. Dans ce but, nous avons réalisé des revues de littérature (3 publications) et une analyse extensive de la base de données Euromelanoma qui couvre 30 pays européens (2 publications).Méthodes. Pour les 3 revues, nous avons cherché dans toute la littérature publiée en anglais sur les moteurs de recherche les plus utilisés, en employant des mots clés pertinents. Les participants des 2 études Euromelanoma ont rempli des questionnaires colligeant les facteurs démographiques et de risque, le type et la durée d’utilisation des bancs solaires. Des analyses multi-variées ont permis d’évaluer les facteurs indépendamment associés à l’usage des bancs solaire dans chaque pays.Résultats. Les revues de littérature ont montré que :(i) les utilisateurs européens sont typiquement des femmes jeunes/adultes, amatrices de soleil, fumeuses, ressortissantes des pays nordiques, motivées par des raisons esthétiques et préférant les centres de bronzage, même si des exceptions existent ;(ii) dans le cas d’une carence en vitamine D, le rapport risque/bénéfice est clairement en faveur de la supplémentation en vitamine D plutôt que du bronzage artificiel ;(iii) tous les critères épidémiologiques de causalité s’appliquent à la relation entre les bancs solaires et le mélanome. Les études Euromelanoma ont été réalisées sur 227,888 individus (67.4% femmes, âge médian 44 ans) issus de 30 pays. La prévalence globale d’utilisation des bancs solaires était 10.6%, mais était plus élevée dans les pays nordiques et non ensoleillés, l’Italie et l’Espagne faisant exception. Dans tous les cas, les femmes avaient une prévalence d’utilisation plus élevée que les hommes. Des particularités géographiques ont été relevées dans 4 régions :la péninsule ibérique (prévalence 10 fois plus élevée en Espagne qu’au Portugal), les Balkans (disproportions excessives de prévalence entre femmes et hommes), les pays baltiques (la prévalence la plus élevée chez les jeunes/adultes), et scandinaves (la prévalence la plus élevée chez les adolescents). Avoir utilisé au moins une fois un banc solaire était indépendamment associé avec :un nombre de naevi >50 [summary odds ratio (SOR)=1.05 (1.01-1.10)], la présence de naevi atypiques [SOR=1.04 (1.00-1.09)] et des lentigines [SOR=1.16 (1.04-1.29)] et la suspicion de mélanome [SOR=1.13 (1.00-1.27)]. Conclusions. La revue complète de la littérature nous permet d’affirmer que le débat sur la relation causale entre bancs solaires et mélanome doit être clos et que leur utilisation pour corriger un déficit sérique en vitamine D n’est pas sans danger. L’analyse Euromelanoma sur l’utilisation des bancs solaires et les facteurs de risque de cancer cutané suggère que le bronzage artificiel devrait toujours être dissuadé, spécialement mais pas exclusivement chez les individus avec des phénotypes à haut risque. Les données de la prévalence et des facteurs déterminant l’utilisation des bancs solaires constituent un intérêt de santé publique et devraient permettre de cibler les actions nécessaires à la réduction du bronzage artificiel en Europe. / Doctorat en Sciences médicales (Médecine) / info:eu-repo/semantics/nonPublished

l’onchocercose et examine les principaux défis liés à l'élimination de l'onchocercose. Pour atteindre nos objectifs, 3 études rétrospectives ainsi que 3 études prospectives ont été réalisées. Ainsi, nous avons constaté que la maladie est présente dans les 26 provinces du pays, celle-ci est méconnue de la population et la participation communautaire au TIDC est faible à cause des effets secondaires du médicament dans les zones coendémiques et l’absence de l’éducation à la santé. Nonobstant les 18 années d’intervention pour contrôler et éliminer l'onchocercose en RDC, l’interruption de la transmission et ou de la prolifération du parasite dans différentes communautés y reste d’actualité. Bien que les stratégies y soient passées de la lutte contre la maladie à son élimination d'ici 2025 selon les projections de l’OMS, elles demeurent tout de même difficiles à atteindre à ce jour en RDC. Plusieurs actions sont encore indispensables pour faciliter l’éradication de la transmission de l’onchocercose en RDC comme :l’épandage aérien d’insecticide, les campagnes d’éducation pour la santé, les formations des distributeurs communautaires et d’agents de santé et la cartographie de toutes les zones de transmission et des zones endémiques à statut inconnu. Il est impérieux de souligner que la lutte contre la maladie est confrontée à certains défis tels que :la coendémicité de l'onchocercose et de la loase, la résistance à l'Ivermectine, la réticence de certaines populations au sein des communautés à adhérer au TIDC, les conflits et troubles civils, les difficultés de mise en œuvre du programme d’ordre technique et financier. Ainsi, nous recommandons :la mise au point d’une cartographie complète de l'élimination, l’adoption d'une approche différente de distribution des médicaments, l’instauration d’une surveillance et évaluation de routine du traitement de masse et le renforcement des partenariats en vue d’une coordination d’activités plus pérenne et d’un financement continu. Le Programme National de Lutte contre les Maladies Tropicales Négligées à Chimiothérapies Préventives (PNLMTN-CTP) doit planifier, coordonner et évaluer régulièrement ses interventions en RDC. Par conséquent, identifier les facteurs empêchant l'interruption de la transmission du parasite et prendre des mesures correctives pour éliminer la maladie en s’inspirant notamment des celles prises en Amériques, s’avèrent indispensables. Par ailleurs, la mise en œuvre des stratégies alternatives de traitement pour accélérer le processus d’élimination de l’onchocercose reste également une priorité.Mots-clés :Onchocercose, Ivermectine, stratégies, mesures, lutte, défis, RDC / Doctorat en Santé Publique / info:eu-repo/semantics/nonPublished

Death from hunger and starvation can be avoided with appropriate diagnosis and treatment if the necessary knowledge and resources are available. The current definitions of acute malnutrition are based either upon a weight-for-height Z-score (WHZ) below -2 standard deviations of the international reference population (World Health Organization 2006 Growth Standards) or a mid-upper arm circumference (MUAC) lower than 125 mm. These indicators are used independently to define the sum of moderate and severe acute malnutrition, commonly referred to as global acute malnutrition (GAM). Severe acute malnutrition (SAM) is defined as the children with WHZ < -3 SD or MUAC <115 mm. These cut-off points are used both to estimate the prevalence of malnutrition and also to identify those children who should be admitted for individual treatment of their acute malnutrition.However, the ramifications of the new WHO standards and the introduction of the absolute MUAC as an additional criterion have not been sufficiently explored. There appears to have been little detailed analysis of the variation of MUAC in children using these new standards. Thus, there is insufficient information available for predicting changes in patient load due to the addition of an absolute MUAC cut-off, the degree of overlap between the criteria and the factors that affect the selection of malnourished children using the two criteria, WHZ and MUACNevertheless, because of the ease of use of MUAC and strong advocacy based mainly the relative sensitivity and specificity of WHZ and MUAC in predicting long-term all-cause mortality in the community, many organizations and some governments are now moving from using MUAC to screen children in the community and elsewhere to MUAC-only programs with abandonment of using WHZ altogether.A better understanding of the relationship between these measures is important as differences can have significant implications on the decision to intervene in a nutritional crises, assessment of potential program size, resource requirements and outcome, selection of children admitted for treatment and the strategy which will have the greatest influence upon mortality and the other poor outcomes of being malnourished. To this end my thesis included the following studies which explored the variation of MUAC and WHZ in children for the assessment of malnutrition.In my first study, I examined the direction and degree of discrepancy between MUAC and WHZ of children aged 6-59 months in 1,832 anthropometric surveys from 47 countries, mainly in Africa. The results show that using MUAC or WHZ, 16.3% of children were identified with GAM and 3.5% with SAM. The proportion of overlap between the two indicators was 28.2% for GAM (15-38.5%) and 16.5 % for SAM (6.1-29.8%). Overlap for individual countries was especially low for SAM. The numbers of children diagnosed by either criterion varied dramatically by country: the difference between the relative case-load using WHZ and MUAC for GAM varied from minus 57% to plus 72%. For SAM, in four of the 38 countries, less than 25% of severely malnourished children would be identified and admitted for treatment if a MUAC-only admission policy were being used. For all countries examined, the discrepancies were not adequately explained by any single hypothesis. My second study was in three parts. Each part examined the veracity of the assertion that MUAC is a better indicator of mortality than WHZ. 1) I analysed individual data from 76,887 children admitted to a range of treatment programmes to determine the mortality rates associated with SAM. 2) I conducted an exhaustive search of the literature to identify reports of children diagnosed by WHZ or MUAC with their respective mortality rates.3) I analysed the effect of case load using the prevalence data published in the first study with Case Fatality Rates (CFRs) derived from the empirical data, the literature data and theoretical simulations. We found that mathematical coupling caused a reversal of significance generating Simpson’s paradox so that the interpretation of the relative mortality rates of WHZ and MUAC is unsafe when children with both criteria are included in each group being compared. The analysis suggests that children with SAM identified by WHZ <-3 and admitted for treatment are at as least as high a risk of death as children in treatment with MUAC<115cm and probably at higher risk. Review of 21 datasets that compared WHZ and MUAC mortality rates show problems with interpretation of the reported CFRs in each of the studies; inconsistencies greatly limit analysis, comparability and interpretation. Caseload is a more important determinant of the number of SAM related child deaths than the relative CFR to give the number of SAM attributable deaths. Where most of the children are identified as SAM using WHZ, rather than MUAC, it is estimated that fewer than half of all SAM related deaths will be identified using a MUAC-only programme.In my third study, I have conducted a Monte Carlo simulation of anthropometric surveys and imposed random errors of measurement on the data in order to examine the effect of measurement error. The results show that there is an increase in the standard deviation with each of the errors, that the spread becomes exponentially greater with the magnitude of the sort of error that occur in real life situations and that the effect of an increase in standard deviation (SD) that appears to be fairly trivial has a major effect upon the reported prevalence of the condition. I show that even within quite a narrow range of SDs (from 0.8 to 1.2) the proportion of children <-2 WHZ can increase from 6% to 15% - which would move the population from one of “acceptable” prevalence to an acute emergency situation. The corresponding SAM would increase from about 1% to nearly 5%. If one was to use such a survey to estimate the current case-load of SAM children the difference would be five-fold. However, this range of SDs is generally thought to represent a “good survey”. When larger and more complex surveys are considered, for example those included in the WHO database or the DHS surveys, the SD is frequently greater than 1.2 leading to give a higher reported prevalence of malnutrition than may be the actual prevalence. In my fourth study, I performed a secondary analysis of the surveys collected in my first study in order to examine the change in reliability of such surveys over time. I analysed the statistical distributions of the derived anthropometric parameters from 1,843 surveys conducted by 19 agencies between 1986 and 2015. The results show that with the introduction of standardised guidelines and software by 2003 and their more general application from 2007 the mean standard deviation, kurtosis and skewness of the parameters used to assess nutritional status have each moved to now approximate the distribution of the WHO standards when the exclusion of outliers from analysis is based upon the SMART flagging procedure. Where WHO flags, that only exclude data incompatible with life, are used the quality of anthropometric surveys has improved and the results now approach those seen with SMART flags and the WHO standards distribution. Agencies vary in their uptake and adherence to standard guidelines. Those agencies that fully implement the guidelines achieve the most consistently reliable results.In conclusion, well-defined and internationally accepted criteria to assess anthropometric survey quality should be universally applied and reported if the surveys are to be reliable, credible and form the basis for appropriate intervention. Using WHZ-only or MUAC-only estimates of prevalence will underestimate the burden of acute malnutrition. Such a program policy would result in between 300,000 and 600,000 SAM deaths occurring in children each year who have no possibility of being treated. WHZ and MUAC are complementary indicators, it is only by using both criteria to identify SAM and admit children for treatment that we will move towards reducing avoidable SAM- related mortality in most countries. This will only be realised when we can conveniently identify children with a low WHZ in community screening programs. / Doctorat en Sciences de la santé Publique / info:eu-repo/semantics/nonPublished