DEP - Teses de doutoramento
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Browsing DEP - Teses de doutoramento by advisor "Nunes, Baltazar"
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- Measurement error in self-reported risk factors for cardiovascular disease: results from the first Portuguese National Health Examination SurveyPublication . Kislaya, Irina; Nunes, Baltazar; Tolonen, HannaABSTRACT - Accurate data on cardiovascular disease risk factors are essential for the design and evaluation of public health policies. Currently, self-reported data on hypertension and hypercholesterolemia constitute a primary data source for population health monitoring at European and national level. This thesis aimed to evaluate accuracy of self-reported data on hypertension and hypercholesterolemia, to quantify, and to correct measurement error bias using data from the first Portuguese Health Examination Survey (INSEF). Measurements of blood pressure and total cholesterol concentrations were used as gold-standards to estimate measurement error bias, sensitivity and specificity of selfreports, investigate error impact on outcome-exposure associations and illustrate application of multiple imputation for bias correction. Despite all the efforts to limit the error through design and fieldwork procedures, self-reported data underestimated prevalence of hypertension and hypercholesterolemia in Portuguese population. Being unequally distributed among socioeconomic subgroups, measurement errors resulted in underestimation of socioeconomic inequalities in younger and overestimation in older age groups. The study results highlight the importance of measurement error bias analysis when using self-reported data. Results from multiple imputation show the approach feasibility for measurement error bias adjustment in prevalence estimates and outcome-exposure associations when individual-level validation data is available. Health statistics on cardiovascular disease risk factors derived from self-reports should be used with caution. Integration of objective measurements in large-scale health surveys will improve the accuracy of epidemiological information on hypertension and hypercholesterolemia. RESUMO - Informação epidemiológica de qualidade sobre os fatores de risco para doenças cardiovasculares é essencial para formulação e avaliação das políticas de saúde. Atualmente, os dados autoreportados sobre hipertensão e hipercolesterolemia constituem uma fonte primária de informação para monitorização da saúde da população a nível europeu e nacional. O objetivo desta tese é avaliar a qualidade dos dados autoreportados sobre hipertensão e hipercolesterolemia, quantificar e corrigir o viés de medição assocados à informação autoreportada utilizando os dados do primeiro Inquérito Nacional de Saúde com Exame Físico (INSEF). Considerando medições diretas da tensão arterial e do colesterol total como padrão, estimou-se a sensibilidade e a especificidade dos dados autoreportados, avaliou-se o impacto do erro da medição nas estimativas da prevalências e medidas de associação. Adicionalmente, o trabalho desenvolvido ilustrou a aplicação de imputação múltipla para correção de viés de medição. Os dados autoreportados subestimaram a prevalência de hipertensão e hipercolesterolemia na população portuguesa comparativamente às medições diretas. O grau diferencial de viés por estatuto socioeconómico leva a subestimação das desigualdades socioeconómicas nos mais jovens e superestimação nos grupos com a idade mais avançada. Os resultados do estudo realçam a importância da análise de viés associados à medição na utilização dos dados autoreportados. Os resultados da imputação múltipla indicam a viabilidade desta estratégia no ajuste das estimativas da prevalência e medidas de associação quando estão disponíveis a nível individual os dados das medições diretas. As estatísticas de saúde derivadas dos dados autoreportados devem ser usadas com cautela. A integração das medições objetivas nos inquéritos de saúde de base populacional permitirá obter informação epidemiológica de melhor qualidade para monitorização da hipertensão e hipercolesterolemia.
- Measuring the impact of influenza vaccination national strategy among the at risk Portuguese populationPublication . Machado, Ausenda; Nunes, Baltazar; Larrauri, AmparoYearly seasonal influenza vaccine is recommended to individuals with chronic conditions or aged ≥65 years (high-risk group). However, for these high-risk individuals, the vaccine coverage has been lower than targeted, vaccine effectiveness may be altered by age or presence of chronic conditions and the impact of the vaccination strategy is still unknown. With focus in the high-risk group, this thesis aimed contributing to the national influenza strategy by providing information on i) influenza vaccine coverage and associated factors; ii) vaccine effectiveness and iii) impact of influenza vaccination strategy at population level. Results indicate that the proportion of individuals with vaccine uptake for four consecutive seasons was only 27%. Age, having a chronic condition and use of health care were positively associated to vaccine uptake. Vaccine effectiveness was estimated in 52% against medically-attended influenza and 32% against influenza hospital admissions in the ones aged ≥65 years. The tested hypothesis of an effect modification of the vaccine by age or chronic conditions, was inconclusive, probably due to lack of power. The impact of influenza vaccination strategy indicate that on average, during the period 2014/15-2017/18, the strategy averted 715 primary care medically attended influenza; 1833 hospitalizations and 383 intra-hospital. The influenza vaccine strategy had consistent and positive benefit in the high-risk population. To maximize the impact, efforts should be conducted to increase the vaccine coverage and the results of this thesis could be used to design targeted strategies. The continuous monitoring of the vaccine effectiveness and population impact could contribute in this effort. RESUMO - A vacina contra a gripe é recomendada anualmente a indivíduos alto-risco de complicações, nomeadamente aqueles com doenças crónicas ou idade ≥65 anos. Contudo, a cobertura da vacina neste grupo de alto-risco é inferior à meta estabelecida, a efetividade pode ser modificada pela idade e pela doença crónica e o impacto da estratégia de vacinação é desconhecido. Com foco nos individuos de alto-risco, esta tese pretendeu contribuir para a estratégia de vacinação contra a gripe fornecendo informações sobre a i) cobertura vacinal e fatores associados, ii) efetividade da vacina e iii) impacto a nível populacional da estratégia de vacinação. Os resultados indicam que a proporção de indivíduos com toma da vacina nas 4 épocas foi de 27%. A idade, ter doença crónica e utilização de cuidados de saúde estavam positivamente associados à toma de vacina. A hipótese de modificação de efeito da vacina pela idade e comorbilidades foi inconclusiva, decorrente provavelmente da falta de potência do estudo. ). A efetividade da vacina foi estimada em 52% na redução de consultas e em 32% na redução de hospitalizações nos indivíduos com ≥65 anos. Por último, a estratégia de vacinação preveniu em média, durante o período em análise (2014/15-2017/18), 715 consultas, 1833 hospitalizações e 383 óbitos intra-hospitalares. A estratégia de vacinação contra a gripe teve benefícios positivos na população de alto-risco. Para maximizar este impacto devem ser realizados esforços para aumentar a cobertura e os resultados desta tese podem ser importantes no delineamento de intervenções direcionadas. A contínua monitorização da efetividade e do impacto da vacina na população poderiam contribuir para esse objetivo.
- Spatial Epidemiology of Cancer: data types, spatial aggregation and geographical patterns in mainland PortugalPublication . Roquette, Rita; Painho, Marco; Nunes, BaltazarThe importance of research on the spatial epidemiology of cancer has been progressively recognized and the number of studies in this field has been increasing steadily, having experienced significant growth over the last decade. Overall, spatial epidemiology is a comprehensive research area that covers a variety of subjects. Among those subjects, and particularly in the case of spatial epidemiology of cancer, one important topic is the level of spatial data aggregation. The analysis of individual data may present ethical data protection issues, so geographically-aggregated data are often used in epidemiological research. Conversely, the analysis of aggregated data also raises certain methodological issues, such as: a) the importance of calculating standardized rates (usually by sex and age) to allow for the comparison of different geographical units; b) the need to take into account the fact that the results obtained at a given level of geographical aggregation cannot be extrapolated as true for other levels of aggregation; and c) the possible existence of the “small numbers problem” and the relevance of using smoothed rates to try to solve it. This thesis takes a first look at this subject through a systematic review of the literature on the spatial epidemiology of cancer. The findings show that the questions which are considered most frequently in the literature consist of: a) the methodology used; b) the spatial distribution of cancer and its temporal evolution; and c) risk factors. The thesis then seeks to address these three aspects. In order to do that, several methodological issues related to the research of the spatial epidemiology of cancer are evaluated and the mortality distribution of all types of cancer is analyzed. Given the high rates of incidence and mortality due to colorectal cancer among the Portuguese population, this cancer type is taken as a case-study, and the distribution of its incidence and mortality is studied and compared with the distribution of the prevalence of the main risk factors. With regard to methodology, it is find that data aggregation at the municipality level makes it possible to obtain detailed information on the geographical distribution of cancer in mainland Portugal, and simultaneously address the small numbers problem. The use of statistical methods to calculate smoothed rates based on the spatial vicinity of the units under analysis also contributes to solving this latter problem. x Doctoral Programme in Information Management As far as cancer’s spatial distribution patterns are concerned, it is find significant heterogeneity across the municipalities of mainland Portugal, both when examining overall cancer mortality and when specifically looking at colorectal cancer incidence and mortality. Regarding the mortality distribution of all cancer types, it is find that the highest mortality rates tend to cluster around Oporto (on the north coast), Lisbon (on the west coast) and in the municipalities of southeast mainland Portugal. With respect to colorectal cancer, it are detected different patterns of incidence and mortality. The distribution of colorectal cancer incidence is more heterogeneous than that of colorectal cancer mortality. In addition, both colorectal cancer incidence and mortality exhibit especially high values for men in two municipalities in the center of mainland Portugal, which seems to call for a more detailed analysis of this area. In terms of risk factors, the following main risks, which have been identified as having a possible association with colorectal cancer, were considered: tobacco smoking; alcohol intake; and dietary behavior. Screening, as a secondary prevention measure aimed at the early detection of cancer and mortality reduction, was also considered in the analysis. However, data on these risk factors are representative only at much more aggregated geographic units, such as NUTS II. Therefore, a detailed analysis of association could not be performed. Finally, the natural background radiation in mainland Portugal was also analyzed, computing a mean by municipalities, and the conclusion is that its association with colorectal cancer is generally weak. This work points to a variety of interesting topics to study in future research, such as: a) to apply the same methodologies to other cancer types; b) to study the geographical association of risk factors, like socio-demographic and environmental risk factors, with cancer incidence and mortality; c) to test other spatial methods in the research of spatial epidemiology of cancer in Portugal, like, for an instance, kriging or multilevel models; and d) to establish suitable methodologies to study spatial epidemiology of cancer in the Portuguese islands.
- Violence against older adults: multidimensional perspectivePublication . Santos, Ana João; Ribeiro, Oscar; Nunes, BaltazarThe first theoretical reference to violence against older adults appeared in 1975, firstly described as “Granny battering”. Since then, the field has dealt with controversy over concepts, definitions and theoretical models used to describe and conceptualise the problem. The difficulties of the fields conceptual development can be partly attributed to the multidimensionality of the construct. Violence against older adults can be defined and categorised according to different dimensions (e.g., abuse types, victim, perpetrator and context), and its theoretical and conceptual development has coexisted with the difficulty of including the various categories of each of these dimensions (and the range of possible presentations) in conceptualisations sufficiently objective for its operationalization and, consequently, for its empirical validation. This thesis recognises that multidimensionality is an essential feature for understanding violence against older adults, since victimisation experiences are characterised, defined and understood within the interplay of abusive behaviours, victims, perpetrators and contexts. Bearing these assumptions in mind, the thesis presents a series of studies that aimed to describe the multidimensionality of violence within community dwelling older adults and to provide a more complex representation of victimisation experiences in a description of configurations encompassing more than one of the problems’ dimensions. First a brief review of the research history and the fields conceptual development is presented, including the multidimensional perspective (chapter I and II). It follows the study empirical work that involves a secondary analysis of data from the Ageing and Violence research project. This was a project that took place between 2011 and 2014, and was conducted by the National Heath Institute Doutor Ricardo Jorge. In the study presented in chapter IV, we determined the impact of employing two different measures to evaluate psychological violence and reflect whether family dynamics is being included within the prevalence of this form of violence. Chapter V includes two studies. The first is a contribution to the validation of two short versions of the Geriatric Depression Scale, both of which have shown to be an appropriate instrument to measure depressive symptoms in old age. The second study proposes an in-depth analysis of the relationship between depressive symptoms and violence, by examining its association with both the individuals’ characteristics and distinct violence dimensions. In chapter VI we describe the main evoked emotions and feelings of community-dwelling older adults who have experienced violence and explore the association between these emotions and individual and distinct violence dimensions. The following two studies (chapter VII) sought to describe and characterise multidimensionality of violence against older adults. The first uses latent class analysis to categorise violence occurrence into subgroups considering two of the problems dimensions - abusive behaviours and appointed perpetrators. The second study is a qualitative study on the narratives and perceptions of self-reported victims. The relationship between victim and abusive individual is considered the key element based upon which we examine the ageing process and the interplay with violence occurrence. Overall, the findings from the different studies suggest: (i) violence against older adults is a construct that encompasses distinct phenomena (Intimate Partner Violence grown old and neglect) sharing common features; (ii) violence against older adults is best characterised by considering different dimensions (e.g., context dyad victim-perpetrator, abusive behaviours and severity); (iii) the dyad victim-perpetrator is one of the most important dimensions, followed by severity and type of abusive behaviours; (iv) the interplay of these different dimensions helps apprehend the nature and dynamics of different elder abuse configurations. In chapter VIII (contribution to the thesis in the form of a chapter of the book manual entitled “Manual sobre “Vítimas de crime e violência: Práticas de intervenção” [Victims of Crime and Violence: Intervention Practices]), we recognise the difficulty of developing a single intervention and, through a case study, we reflect on the importance of the nature of the relationship between victim and abusive individual for the responses´ appropriateness. Altogether, these studies advance new knowledge on violence against community-dwelling older adults, providing important clues to victimisation configurations-types to which practitioners can tailor specific responses, creating more comprehensive and, hopefully, more effective interventions.