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Identificação de padrões alimentares na dieta de doentes com degenerescência macular relacionada com a idade
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Resumo(s)
A degenerescência macular da idade (DMI) é a principal causa de cegueira irreversível entre as
pessoas com idade igual ou superior a 55 anos nos países desenvolvidos (Shaw et al., 2016; Lim
et al., 2012). Atualmente, os tratamentos de DMI têm um custo elevado e restringem-se apenas ao retardamento da progressão da forma neovascular da doença. Vários estudos sugeriram que alguns aspetos da dieta podem influenciar o risco de desenvolvimento e/ou progressão da doença, no entanto, os resultados obtidos foram maioritariamente baseados em análises do consumo individual de nutrientes e alimentos ou grupos de alimentos (Age-Related Eye Disease Study Research Group et al., 2008; Tan et al., 2009; Chong et al., 2009). A avaliação de padrões dietétios tem surgido, na área da epidemiologia nutricional, como uma ferramenta mais informativa e preditiva do risco da doença, uma vez que permite estudar a dieta como um todo (Hu, 2002). Apenas dois artigos reportaram a avaliação de associações entre padrões alimentares e o risco de DMI (Chiu et al., 2014; Islam et al., 2014), contudo, ainda nenhum estudo foi realizado para a população portuguesa. Este projeto pretendeu, deste modo, identificar os principais padrões alimentares de uma subpopulação com idade superior a 55 anos da Lousã, uma região rural do interior de Portugal, e analisar a respetiva associação com o risco de DMI. Para tal, foram analisados os dados demográficos, de história médica geral e oftalmológica referentes a uma amostra de 1000 participantes da Unidade de Saúde Familiar da Lousã, com uma proporção de 1:1 de sujeitos com e sem DMI, disponíveis na base de dados construída no estudo transversal Coimbra Eye Study e também os dados obtidos pela realização de um questionário semi-quantitativo de frequência alimentar, previamente validado para a população portuguesa. Inicialmente, para a determinação dos principais padrões alimentares da população em estudo, foi utilizada a metodologia de análise em componentes principais (ACP), e confirmados os respectivos resultados com análise classificatória (AC). Seguidamente, procedeu-se à construção de modelos de regressão logística binária, onde a variável resposta consistiu na presença/ausência de DMI. As variáveis explicativas consideradas foram os padrões alimentares retidos com ACP e outros factores de risco potenciais da doença, como a idade, sexo, escolaridade, índice de massa corporal (IMC),
perímetro abdominal, hábitos tabágicos, atividade física, consumo energético total e alcoólico, diabetes, hipertensão e dislipidémia. Uma vez que este projeto teve como foco analisar especificamente os efeitos dos padrões alimentares com a doença, procurou-se diminuir o confundimento residual através do desenvolvimento e aplicação de um método que permitiu simultaneamente a seleção das variáveis de confundimento e da forma funcional das covariáveis contínuas. Neste estudo foram identificados três padrões alimentares: um padrão que refletiu uma dieta tradicional, típica da região interior portuguesa, um padrão saudável e um padrão menos saudável, que se distinguiu dos anteriores pelo elevado consumo de alimentos de fácil preparação ou petiscos. Foram encontradas associações entre o padrão tradicional e o padrão saudável e o risco de DMI, porém apenas ao nível de significância de _ = 0:1. O padrão tradicional revelou estar associado positivamente com o risco de DMI, enquanto que o padrão saudável revelou ter um papel protetor no desenvolvimento da doença. O padrão menos saudável não demonstrou qualquer associação significativa com o risco de DMI.
Os resultados aqui obtidos suportam, assim, o papel importante da dieta no desenvolvimento de DMI, à semelhança do ocorrido nos outros dois estudos realizados para outras populações. Tal poderá providenciar uma melhor compreensão da relação entre a doença e as práticas alimentares na população estudada e poderá fornecer informação adicional para um maior apoio à educação, aconselhamento e intervenção nutricional. Neste estudo, concluiu-se que uma dieta rica em iogurte, peixe, fruta, hortícolas, salada e sopa é mais aconselhável para prevenção da doença quando comparada a uma dieta abundante em carnes vermelhas, bacalhau, acompanhamentos (arroz, massa, batatas cozidas ou assadas), pão branco ou integral, tostas e broa, azeite, bebidas alcoólicas e café.
Age-related macular degeneration (AMD) is the major cause of irreversible blindness among people aged 55 or over in developed countries(Shaw et al., 2016; Lim et al., 2012). Currently, clinical treatments for AMD are costly and are limited to arresting the neovascular type of the disease. Several studies have suggested that some aspects of diet could influence the risk of disease development and/or progression, although the results have largely been based on analysis evaluating individual nutrient, food or food groups (Age-Related Eye Disease Study Research Group et al., 2008; Tan et al., 2009; Chong et al., 2009). Dietary pattern analysis has emerged in the field of nutritional epidemiology as a more informative and predictive tool of disease risk, since it allows to study a diet as a whole (Hu, 2002) to understand how it can be optimized to promote health. Only two articles have examined the relationship between dietary patterns and the risk of AMD (Chiu et al., 2014; Islam et al., 2014), however no studies have yet been reported for the Portuguese population. Thus, initially, this project aimed to identify major food patterns of a subpopulation over 55 years of Lousã, a rural interior area in Portugal, and, subsequently, to evaluate potential associations with the risk of AMD. According to the objectives set, one analysed demographic, general medical and ophthalmological data collected from a sample of 1000 participants from the Family Health Unit of Lousã, with a ratio of 1:1 of subjects with and without AMD, available in the database constructed in the cross-sectional study Coimbra Eye Study and also the data obtained by administering a semi-quantitative food frequency questionnaire previously validated for the Portuguese population. Principal components analysis (PCA) was used to determine the major dietary patterns of the study population, and the results obtained were confirmed with clustering analysis (CA). Afterwards, binary logistic regression models were constructed, where the response variable was the presence/absence of AMD. The explanatory variables considered were food patterns retained with PCA and other potential risk factors of the disease, such as age, sex, formal education, body mass index (BMI), abdominal circumference, smoking habits, physical activity, total energy intake and alcohol intake, diabetes, hypertension and dyslipidemia. Since the main focus of this project was to comprehend the effects of dietary patterns on the disease, it was sought to reduce residual confounding through the development and application of a method that simultaneously allowed the selection of confounding variables and the functional forms of continuous covariates. Three dietary patterns were identified: a pattern that reflected a traditional diet typical of the Portuguese interior region, a healthy pattern and a less healthy pattern, which was distinguished from previous ones by the high consumption of easily prepared foods or snacks. Associations were found between the traditional pattern and the healthy pattern and the risk of AMD, but only at the significance level of _ = 0:1. The traditional pattern seems to potentiate the risk of AMD, while the healthy pattern seems to play a protective role in the development of AMD. The less healthy pattern did not shown any significant association with the risk of AMD. The results obtained here support the important role of diet in the development of AMD, as in the other two studies performed for other populations. This may provide a better understanding of the relationship between disease and dietary practices in the population studied and may provide additional information for further support to education, counseling and nutritional intervention. In this study, it was concluded that a diet rich in yogurt, fish, fruit, vegetables, salads and soup is more advisable for disease prevention when compared to a diet rich in red meat, cod, side dishes (rice, pasta, cooked or roasted potatoes), white or whole grain bread, toasted bread, olive oil, alcoholic beverages and coffee.
Age-related macular degeneration (AMD) is the major cause of irreversible blindness among people aged 55 or over in developed countries(Shaw et al., 2016; Lim et al., 2012). Currently, clinical treatments for AMD are costly and are limited to arresting the neovascular type of the disease. Several studies have suggested that some aspects of diet could influence the risk of disease development and/or progression, although the results have largely been based on analysis evaluating individual nutrient, food or food groups (Age-Related Eye Disease Study Research Group et al., 2008; Tan et al., 2009; Chong et al., 2009). Dietary pattern analysis has emerged in the field of nutritional epidemiology as a more informative and predictive tool of disease risk, since it allows to study a diet as a whole (Hu, 2002) to understand how it can be optimized to promote health. Only two articles have examined the relationship between dietary patterns and the risk of AMD (Chiu et al., 2014; Islam et al., 2014), however no studies have yet been reported for the Portuguese population. Thus, initially, this project aimed to identify major food patterns of a subpopulation over 55 years of Lousã, a rural interior area in Portugal, and, subsequently, to evaluate potential associations with the risk of AMD. According to the objectives set, one analysed demographic, general medical and ophthalmological data collected from a sample of 1000 participants from the Family Health Unit of Lousã, with a ratio of 1:1 of subjects with and without AMD, available in the database constructed in the cross-sectional study Coimbra Eye Study and also the data obtained by administering a semi-quantitative food frequency questionnaire previously validated for the Portuguese population. Principal components analysis (PCA) was used to determine the major dietary patterns of the study population, and the results obtained were confirmed with clustering analysis (CA). Afterwards, binary logistic regression models were constructed, where the response variable was the presence/absence of AMD. The explanatory variables considered were food patterns retained with PCA and other potential risk factors of the disease, such as age, sex, formal education, body mass index (BMI), abdominal circumference, smoking habits, physical activity, total energy intake and alcohol intake, diabetes, hypertension and dyslipidemia. Since the main focus of this project was to comprehend the effects of dietary patterns on the disease, it was sought to reduce residual confounding through the development and application of a method that simultaneously allowed the selection of confounding variables and the functional forms of continuous covariates. Three dietary patterns were identified: a pattern that reflected a traditional diet typical of the Portuguese interior region, a healthy pattern and a less healthy pattern, which was distinguished from previous ones by the high consumption of easily prepared foods or snacks. Associations were found between the traditional pattern and the healthy pattern and the risk of AMD, but only at the significance level of _ = 0:1. The traditional pattern seems to potentiate the risk of AMD, while the healthy pattern seems to play a protective role in the development of AMD. The less healthy pattern did not shown any significant association with the risk of AMD. The results obtained here support the important role of diet in the development of AMD, as in the other two studies performed for other populations. This may provide a better understanding of the relationship between disease and dietary practices in the population studied and may provide additional information for further support to education, counseling and nutritional intervention. In this study, it was concluded that a diet rich in yogurt, fish, fruit, vegetables, salads and soup is more advisable for disease prevention when compared to a diet rich in red meat, cod, side dishes (rice, pasta, cooked or roasted potatoes), white or whole grain bread, toasted bread, olive oil, alcoholic beverages and coffee.
Descrição
Tese de mestrado em Bioestatística, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2017
Palavras-chave
Degenerescência macular da idade Padrões alimentares Análise em componentes principais Modelos de regressão logística binária Confundimento residual Teses de mestrado - 2017