Teses e Dissertações

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High prevalence of asthma in pre-school children in southern brazil: a population-based study The prevalence of asthma is increasing in many countries. To measure asthma’s prevalence, a sample of 981 children aged 4 years old belonging to a birth cohort from 1993 was studied in Pelotas, a city in southern Brazil. A standardised questionnaire on asthma was applied to the children’s mothers. Information was also collected on socio-economic level, housing conditions, genetic factors, nutritional factors and previous infectious diseases. Current asthma (asthma diagnosed by a doctor during the previous 12 months) and current wheeze (presence of wheezing during the previous 12 months) were the main outcomes. The prevalence of current asthma was 18,4% and current wheeze, 21,1%. The data was analyzed by multiple Poisson regression and the risk factors that remained significant for both “current asthma and current wheeze� were, respectively: non-white color (RR=1,41 and RR=1,36), low maternal schooling (RR= 1,75 and RR=1,68 for 0-4 years), history of asthma or allergy in the family (RR= 1,66 and RR=1,85) and history of rhinitis and eczema in the child (RR=2,11 and RR=1,72). Male sex (RR=1,36) and bronchiolitis (RR=1,46) were major risk factors only for “current asthma�, while smoking in pregnancy (RR=1,30) and low birth weight (RR=1,45) were risk factors only for “current wheeze�. These results highlight the importance of asthma as a public health problem due to its high prevalence and it supports the need of intervention programs against preventable risk factors. Keywords: asthma, wheeze, epidemiology, risk factors, child, prevalence, and symptoms.

Asthma and lung function in a 6-7 years old birth cohort in Southern BrazilBackground: Asthma and respiratory symptoms are very common in children and many studies have shown an association of them with decreased lung function in adult life. The purposes of this study were to investigate the association of several respiratory symptoms with lung function in a cohort of 6-7 year-old and assess the associations with atopy and demographic, socio-economic, environmental and gestational factors.Methods: The target population consisted of children aged 6 to 7 years old from a birth cohort of 5304 children born in 1993, in Southern Brazil. For the present follow-up, 532 children were randomly selected and a sub-sample was submitted to spirometry, skin prick test and a questionnaire was applied to their parents. Results: The mean coefficients of FEV1/FVC were smaller in children with current wheeze and asthma, asthma ever, four or more wheeze attacks in the last year, sleep disturbed by wheeze and wheeze after exercise. Reduction in mean coefficient of FEF50% and FEF75% was associated with asthma current or ever, four or more wheeze attacks during the last year, sleep disturbed by wheeze and wheeze after exercise. Persistent wheeze was associated with reduced FEV1/FVC, FEF50% and FEF75%. After multiple linear regression, exercise-wheeze was the independent respiratory symptom associated with reductions in coefficient of FEF50% and FEF75%. Skin colour non-white and speech disturbed by wheeze were found to be independent associated factors of diminished mean coefficient of FEV1. Conclusion: Children with persistent wheeze and symptoms of severity of asthma have impaired lung function at 6 - 7 years old.Key Words: asthma, childhood, lung function, wheeze, respiratory symptoms.

Asma e baixo peso ao nascer: uma revisão sistemática da literatura O aumento do índice de sobrevivência de recém-nascidos com muito baixo peso ao nascer (MBPN: menos de 1.500g) tem sido associado à prevalência de asma e sintomas respiratórios na infância. Foram identificados estudos que investigaram esta associação, através das bases de dados Medline e Lilacs, no período de 1990 a 2001. As palavras-chave utilizadas foram “asthma� e “children� e “birth weight� ou “risk factors�. Também se procurou outros estudos através de artigos afins e busca manual. Foram identificados 41 artigos que tratavam do estudo da associação entre peso ao nascer e asma ou sintomas de asma, sendo que, quanto ao delineamento, 16 destes tinham delineamento transversal, 21 longitudinal e 4 estudos de caso-controle. Baixo peso ao nascer foi identificado como fator de risco para asma em 26 estudos, sendo que dois estudos encontraram associação inversa entre peso ao nascer e o risco de asma e 15 não encontraram a associação estudada. Analisando-se os estudos encontrados na literatura pode-se concluir que a maior ocorrência de associação de baixo peso ao nascer e asma é observada na faixa etária da infância. A maioria dos estudos que comparou crianças com BPN (< 2500 g) com crianças de MBPN encontrou esse último como um fator de risco maior para asma do que o primeiro. Outro aspecto importante é o papel da função pulmonar na associação entre asma e baixo peso ao nascer, ou seja: as crianças nascidas com baixo peso podem ter função pulmonar diminuída e, conseqüentemente, desenvolverem quadros de asma. A associação de peso ao nascer e asma permanece ainda controversa na literatura, devido principalmente, à ampla rede de fatores causais que concorrem para a determinação da asma. O esclarecimento dessa associação é muito importante, por tratar-se de característica que pode ser revertida com adoção e implementação de cuidados pré-natais adequados. Palavras-chave: baixo peso ao nascer, muito baixo peso ao nascer, asma, fatores de risco, revisão sistemática.