[Prevalence and risk factors for asthma in schoolchildren in southern Brazil]. / Prevalência e fatores de risco para asma em escolares de uma coorte no Sul do Brasil.

OBJECTIVE: To study the prevalence and risk factors for asthma in a cohort of 494 children born in 1993 and followed up to the age of six years in Pelotas, state of Rio Grande do Sul, Brazil. METHODS: A standardized and validated asthma questionnaire, based on the International Study of Asthma and Allergies in Childhood (ISAAC), was applied. Other information was also collected about socioeconomic background, genetic, nutritional, gestational and allergic factors, and previous infectious episodes. RESULTS: The prevalence of asthma found in this study was 12.8% (95%CI: 10-15.9%). In the multivariate analysis, risk factors such as non-white skin color (RR = 1.9 95% CI: 1.1-3.3%), family history of asthma (RR = 2.8 95% CI: 1.5-5.1), allergic rhinitis in children (RR = 2.6 95% CI: 1.5-4.4) and maternal smoking during pregnancy (RR = 1.7 95%CI: 1-2.9) were associated with asthma. CONCLUSION: Childhood asthma is highly prevalent in Pelotas, and it is a serious public health problem. Therefore, specific programs should be developed for its control.

Prevalência e fatores de risco para asma em escolares de uma coorte no Sul do Brasil / Prevalence and risk factors for asthma in schoolchildren in southern Brazil

OBJETIVOS: Estudar a prevalência e fatores de risco para asma em 494 crianças pertencentes à coorte de nascidos em 1993, as quais vêm sendo acompanhadas desde o nascimento, estando, atualmente, com cerca de 6 anos de idade, em Pelotas (RS). MÉTODOS: Foi administrado um questionário padronizado com questões relativas à asma, baseadas em questionário utilizado por um estudo internacional multicêntrico (ISAAC) validado em diversos países. Também obteve-se informações sobre o nível socioeconômico, fatores ambientais, hereditários, nutricionais, gestacionais, alérgicos e eventos infecciosos pregressos. RESULTADOS: A prevalência de asma encontrada foi de 12,8 por cento (IC95 por cento: 10-15,9 por cento). Na análise multivariada, a asma esteve associada com cor da pele não-branca (RR = 1,9 IC95 por cento: 1,1-3,3 por cento), história de asma na família (RR = 2,8 IC95 por cento:1,5-5,1), rinite alérgica na criança (RR = 2,6 IC95 por cento:1,5-4,4) e fumo na gestação (RR = 1,7 IC95 por cento:1-2,9). CONCLUSÃO: A asma infantil tem elevada prevalência em Pelotas, sendo um problema de saúde pública e, como tal, deve-se direcionar ações apropriadas para o seu controle.

[The association between low birthweight and asthma: a systematic literature review]. / Associação entre baixo peso ao nascer e asma: uma revisão sistemática da literatura.

OBJECTIVE: To determine if there is an association between low birthweight (< 2,500 g) and asthma. RESULTS: The key words "asthma," "children," "birth weight," and "risk factors" were used to identify analytical epidemiological studies on humans that were published in English, Portuguese, or Spanish between 1990 and 2001 and that were indexed in either of two bibliographic databases: MEDLINE (PubMed) and Latin American and Caribbean Health Sciences (Literatura Latino-Americana e do Caribe em Ciências da Saúde (LILACS)). We identified 41 articles dealing with the association between birthweight and asthma: 21 were longitudinal studies, 16 were cross-sectional studies, and 4 were case-control studies. Low birthweight was identified as a risk factor for asthma in 26 of the articles. Two studies found an inverse association between birthweight and risk for asthma, and 15 did not find any association. CONCLUSIONS: The association between low birthweight and asthma remains controversial, mainly due to the extensive network of factors that contribute to the development of asthma. The association between low birthweight and asthma occurs mainly among children up to 5 years of age, and it decreases as age increases. Pulmonary function is an important factor that needs to be considered. Low birthweight children may have decreased pulmonary function and consequently develop asthma. On the other hand, these children may have asthma as a consequence of low birthweight, without pulmonary function being a factor. In the six studies comparing low birthweight children (< 2,500 g) with very low birthweight children (< 1,500 g), very low birthweight was associated with a greater risk for developing asthma. Finally, the contribution of intrauterine factors (such as nutrition) in the development of asthma is receiving increasing attention in the scientific literature. Controlling for possible confounding factors is essential to clarifying the relationship between birthweight and asthma.

High prevalence of asthma in preschool 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 standardized questionnaire on asthma was given to the children's mothers. Information was also collected on socioeconomic level, housing conditions, genetic factors, nutritional factors, and previous infectious diseases. Current asthma (asthma diagnosed by a doctor during previous 12 months) and current wheeze (presence of wheezing during previous 12 months) were the main outcomes. The prevalence of current asthma was 18.4%, and current wheeze was 21.1%. The data were analyzed by multiple Poisson regression, and the risk factors that remained significant for both "current asthma and current wheeze" were, respectively, nonwhite 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 support the need of intervention programs against preventable risk factors.