ABSTRACT
OBJECTIVE: To determine the relation between body mass index and the development of asthma in children. DESIGN: Prospective study of 4393 asthma-free children followed for up to 14 years. SETTING: Children of participants in the National Longitudinal Survey of Youth. METHODS: Analysis was limited to children who were followed from birth and were asthma-free during the first 24 months of life. The outcome was the development of asthma during follow-up (incident asthma). Body mass index (BMI) was our main predictor of interest. Survival analyses, using time to development of asthma as the main endpoint, were stratified by sex and controlled for race/ethnicity, poverty status, and prenatal maternal smoking. RESULTS: Asthma developed in 218 (5.0 %) children during the follow-up period. The relation between BMI and incident asthma varied by sex. A BMI > or =85th percentile at age 2-3 years was a risk factor for subsequent asthma development in boys (hazard ratio (HR) 1.6 95% confidence interval (CI) 1.1, 2.4) but not girls (HR 0.8, 95% CI 0.5, 1.4). Similarly, boys with BMIs always > or =85th percentile were at increased risk for subsequent asthma development (HR 2.4, 95% CI 1.4, 4.4) but not girls (HR 1.5, 95% CI 0.7, 2.9). CONCLUSION: Boys with high body masses may be at an increased risk for developing asthma.
Subject(s)
Asthma/etiology , Obesity/complications , Asthma/epidemiology , Birth Weight , Body Mass Index , Epidemiologic Methods , Female , Humans , Infant, Newborn , Male , Mothers/psychology , Obesity/epidemiology , Poverty/statistics & numerical data , Pregnancy , Prenatal Exposure Delayed Effects , Sex Factors , Smoking , United States/epidemiologyABSTRACT
BACKGROUND: A study was undertaken to determine the relation between urinary cadmium levels and lung function in a nationally representative cohort of current, former, and never smokers in the US. Urinary cadmium levels reflect the total body burden of cadmium. METHODS: The following data from the Third National Health and Nutrition Examination Survey were analysed: urinary cadmium (adjusted for urinary creatinine), lung function, sex, race/ethnicity, age, education level, job category, body mass index, serum cotinine level, and smoking history. Linear regression models were developed to predict lung function using urinary cadmium as the main predictor, adjusting for other covariates and stratified by smoking status. RESULTS: Data were available on 16 024 adults. Current smokers had higher mean (SE) urinary cadmium/creatinine levels (0.46 (0.01) micro g/g) than former (0.32 (0.01) micro g/g) or never smokers (0.23 (0.01) micro g/g). Higher levels of urinary cadmium were associated with significantly lower forced expiratory volumes in 1 second (FEV(1)) in current (-2.06%, 95% confidence interval (CI) -2.86 to -1.26 per 1 log increase in urinary cadmium) and former smokers (-1.95%, 95% CI -2.87 to -1.03) but not in never smokers (-0.18%, 95% CI -0.60 to 0.24). Similar results were obtained for forced vital capacity (FVC) and FEV(1)/FVC. CONCLUSIONS: Cadmium, which is known to cause emphysema in occupational settings, may also be important in the development of tobacco related lung disease.