American journal of epidemiology
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Multicenter Study
Association of environmental tobacco smoke exposure in childhood with early emphysema in adulthood among nonsmokers: the MESA-lung study.
Mechanical stress to alveolar walls may cause progressive damage after an early-life insult such as exposure to environmental tobacco smoke (ETS). This hypothesis was examined by using data from the Multi-Ethnic Study of Atherosclerosis (MESA), a population-based cohort aged 45-84 years, free of clinical cardiovascular disease, recruited from 6 US sites in 2000-2002. The MESA-Lung Study assessed a fractal, structural measure of early emphysema ("alpha," lower values indicate more emphysema) and a standard quantitative measure ("percent emphysema") from cardiac computed tomography scans. ⋯ Analyses included 1,781 nonsmokers (<100 cigarettes, 20 cigars, or 20 pipefulls in their lifetime and urinary cotinine levels <100 ng/mL); mean age was 61 years (standard deviation, 10), and 65% were women. Childhood ETS exposure from 2 or more smokers (17%) compared with none (52%) was associated with 0.05 lower alpha and 2.8 higher percent emphysema (P for trend = 0.04 and 0.01, respectively) after adjustment for demographic, anthropometric, parental, and participant characteristics, as well as adult exposures (e.g., cumulative residential air pollution exposure, exposure to ETS as an adult). Childhood ETS exposure was associated with detectable differences on computed tomography scans of adult lungs of nonsmokers.
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This study aimed to investigate the effect of the timing, dose, and source of folate during pregnancy on childhood asthma by using data from an Australian prospective birth cohort study (n = 557) from 1998 to 2005. At 3.5 years and 5.5 years, 490 and 423 mothers and children participated in the study, respectively. Maternal folate intake from diet and supplements was assessed by food frequency questionnaire in early (<16 weeks) and late (30-34 weeks) pregnancy. ⋯ The effect sizes did not change with adjustment for potential confounders. The association was similar at 5.5 years but did not reach statistical significance (RR = 1.17, 95% CI: 0.96, 1.42) in univariable models. These findings on childhood asthma support previous observations that supplementation with folate in pregnancy leads to an allergic asthma phenotype in mice via epigenetic mechanisms and is associated with poorer respiratory outcomes in young children.
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Infertility treatments that include ovulation stimulation, both assisted reproductive technologies (ARTs) and non-ART ovulation stimulation, are associated with increased risks of multiple birth and concomitant sequelae and adverse outcomes, even among singletons. While a US surveillance system for ART-induced births is ongoing, no population-based tracking system exists for births resulting from non-ART treatments. The authors developed a multistage model to estimate the uncertain proportion of US infants born in 2005 who were conceived by using non-ART ovulation treatments. ⋯ They used Bayesian meta-analyses to summarize published clinical studies on the multiple-gestation risk associated with non-ART ovulation treatments, applied a fetal survival factor, and used this multiple-birth risk estimate and their own estimate of the proportion of US multiple births attributable to non-ART ovulation stimulation to estimate the total (and, through subtraction, singleton) proportion of infants conceived with such treatments. On the basis of the model, the authors estimate that 4.6% of US infants born in 2005 (95% uncertainty range: 2.8%-7.1%) resulted from non-ART ovulation treatments. Notably, this figure is 4 times greater than the ART contribution.
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Concerns about respiratory conditions have surfaced among persons deployed to Iraq and Afghanistan. Data on 46,077 Millennium Cohort Study participants who completed baseline (July 2001-June 2003) and follow-up (June 2004-February 2006) questionnaires were used to investigate 1) respiratory symptoms (persistent or recurring cough or shortness of breath), 2) chronic bronchitis or emphysema, and 3) asthma. Deployers had a higher rate of newly reported respiratory symptoms than nondeployers (14% vs. 10%), while similar rates of chronic bronchitis or emphysema (1% vs. 1%) and asthma (1% vs. 1%) were observed. ⋯ Among deployers, elevated odds of symptoms were associated with land-based deployment as compared with sea-based deployment. Although respiratory symptoms were associated with deployment, inconsistency in risk with cumulative exposure time suggests that specific exposures rather than deployment in general are determinants of postdeployment respiratory illness. Significant associations seen with land-based deployment also imply that exposures related to ground combat may be important.
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Health-care-associated methicillin-resistant Staphylococcus aureus (MRSA) infection may cause increased hospital stay, or sometimes death. Quantifying this effect is complicated because the exposure is time dependent: infection may prolong hospital stay, while longer stays increase infection risk. In this paper, the authors overcome these problems by using a multinomial longitudinal model to estimate the daily probability of death and discharge. ⋯ Infection on the first day of admission resulted in a mean extra stay of 0.3 days (95% credible interval: 0.1, 0.5) for a patient with an Acute Physiology and Chronic Health Evaluation II score of 10 and 1.2 days (95% credible interval: 0.5, 2.0) for a patient with a score of 30. The decrease in the relative risk of discharge remained fairly constant with day of MRSA infection but was slightly stronger closer to the start of infection. Results confirm the importance of MRSA infection in increasing stay in an intensive care unit but suggest that previous work may have systematically overestimated the effect size.