ISSN:1044-3983    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:1044-3983    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:1044-3983    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

We assessed the contributions of particulate matter with aerodynamic diameters ≤10 and ≤2.5 μm (PM2.5and PM10) and ozone (O3) to peak expiratory flow (PEF) and respiratory symptoms in 40 schoolchildren 8–11 years of age for 59 days during three periods in 1991 at a school in southwest Mexico City. We measured peak expiratory flow in the morning on the children's arrival at school and in the afternoon before their departure from school. Separately for morning and afternoon, we normalized each child's daily measurement of peak flow by subtracting his or her mean peak flow from the daily measurement. Child-specific deviations were averaged to obtain a morning and afternoon mean deviation (ΔPEF) for each day. Mean 24-hour O3level was 52 parts per billion (ppb; maximum 103 ppb); mean 24-hour PM2.5and PM10were 30 μg/m3(maximum 69 μg/m3) and 49 μg/m3(maximum 87 μg/m3), respectively. We adjusted moving average and polynomial distributed lag multiple regression analyses of ΔPEF vs pollution for minimum daily temperature, trend, and season. We examined effects of PM2.5, PM10, and O3, on ΔPEF separately and in joint models. The models indicated a role for both particles and O3in the reduction of peak expiratory flow, with shorter lags between exposure and reduction in peak expiratory flow for O3than for particle exposure (0–4vs4–7 days). The joint effect of 7 days of exposure to the interquartile range of PM2.5(17 μg/m3) and O3(25 ppb) predicted a 7.1% (95% confidence interval = 11.0–3.9) reduction in morning peak expiratory flow. Pollutant exposure also predicted higher rates of phlegm; colinearity between pollutants limited the potential to distinguish the relative contribution of individual pollutants. In an area with chronically high ambient O3levels, school children responded with reduced lung function to both O3and particulate exposures within the previous 1 to 2 weeks. (Epidemiology 1999; 10:8–16)

ISSN:1044-3983    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

This study examines the consistency of the association between particulate matter less than 10 μm in aerodynamic diameter (PM10), carbon monoxide (CO), and hospital admissions for cardiovascular disease across eight urban counties with different levels of correlation between pollutants and between the pollutants and weather. I fit Poisson regression models controlling for day-of-week effects and using nonparametric smoothing to control for season and weather. Daily variation in PM10was associated with hospital admissions for heart disease in the elderly (2.48% increase, for an interquartile range increase in exposure; 95% confidence limits = 1.82%, 3.15%). Daily variation in CO was also associated with admissions (2.79% increase, for an interquartile range (1.75 parts per million) increase in exposure; 95% confidence limits = 1.89%, 3.68%). These associations held in both humid and dry locations and were independent of the correlation between the pollutants and weather or other pollutants. The effect size estimates for PM10and CO likewise showed no association with their correlation in each location, as one would expect if one pollutant were merely a proxy for the other. The PM10effects are consistent with recent animal data showing cardiovascular effects and with preliminary human data showing effects on heart rate variability and plasma viscosity. The CO results are consistent with literature on angina exacerbations. (Epidemiology 1999;10:17–22)

ISSN:1044-3983    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

As part of the Clean Air Act, Congress has directed EPA to set air quality standards to protect sensitive population groups from air pollutants in the ambient environment. People with asthma represent one such group. We undertook a study of the relation between measured ambient air pollutants in Seattle and nonelderly hospital admissions with a principal diagnosis of asthma. We regressed daily hospital admissions to local hospitals for area residents from 1987 through 1994 on particulate matter less than 10 and 2.5 μm in aerodynamic diameter (PM10and PM2.5, respectively); coarse particulate mass; sulfur dioxide (SO2); ozone (O3); and carbon monoxide (CO) in a Poisson regression model with control for time trends, seasonal variations, and temperature-related weather effects. With the exception of seasonally monitored O3, we supplemented incomplete pollutant measures in a multiple imputation model to create a complete time series of exposure measures. We found an estimated 4–5% increase in the rate of asthma hospital admissions associated with an interquartile range change in PM (19 μg/m3PM10,11.8 μg/m3PM2.5, and 9.3 μg/m3coarse particulate mass) lagged 1 day; relative rates were as follows: for PM10, 1.05 [95% confidence interval (CI) = 1.02–1.08]; for PM2.5, 1.04 (95% CI = 1.02–1.07); and for coarse particulate mass, 1.04 (95% CI = 1.01–1.07). In single-pollutant models we also found that a 6% increase in the rate of admission was associated with an interquartile range change in CO (interquartile range, 924 parts per billion; 95% CI = 1.03–1.09) at a lag of 3 days and an interquartile range change in O3(interquartile range, 20 parts per billion; 95% CI = 1.02–1.11) at a lag of 2 days. We did not observe an association for SO2. We found PM and CO to be jointly associated with asthma admissions. We estimated the highest increase in risk in the spring and fall seasons. (Epidemiology 1999;10:23–30)

ISSN:1044-3983    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

A relation between water hardness and cardiovascular death has been shown in previous studies. In this case-control study, we investigated the levels of magnesium and calcium in drinking water and death from acute myocardial infarction among women. The study population encompassed 16 municipalities in southern Sweden. Cases were women who had died from acute myocardial infarction between the ages of 50 and 69 years during 1982–1993 (N = 378), and controls were women who had died from cancer (N = 1,368). We obtained magnesium and calcium concentrations of the individual water sources. We divided the subjects into quartiles and found that odds ratios (ORs) were lower at higher levels of both magnesium and calcium. For the quartile with the highest magnesium levels (≥9.9 mg/liter), the OR adjusted for age and calcium was 0.70 (95% confidence interval = 0.50–0.99). For calcium, the adjusted OR for the quartile with the highest level (≥70 mg/liter) was 0.66 (95% confidence interval = 0.47–0.94). The results suggest that magnesium and calcium in drinking water are important protective factors for death from acute myocardial infarction among women. (Epidemiology 1999;10:31–36)

ISSN:1044-3983    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Causal diagrams have a long history of informal use and, more recently, have undergone formal development for applications in expert systems and robotics. We provide an introduction to these developments and their use in epidemiologic research. Causal diagrams can provide a starting point for identifying variables that must be measured and controlled to obtain unconfounded effect estimates. They also provide a method for critical evaluation of traditional epidemiologic criteria for confounding. In particular, they reveal certain heretofore unnoticed shortcomings of those criteria when used in considering multiple potential confounders. We show how to modify the traditional criteria to correct those shortcomings. (Epidemiology 1999;10:37–48)

ISSN:1044-3983    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

We assessed the relation between beta-carotene consumption at various times in life and breast cancer risk by conducting a case-control study nested within a population-based cohort of women screened for breast cancer in Sweden. We conducted a telephone interview with 273 incident breast cancer cases and 371 controls about their diet at various ages throughout their lifetime. Controls were frequency matched to cases on age, month and year of mammography, and county of residence. We used unconditional logistic regression to measure the association between beta-carotene intake and breast cancer risk while adjusting for total energy intake, recency of intake, and the matching variables. Women were at lower risk with increasing levels of reported intake of beta-carotene. This pattern of association between breast cancer and beta-carotene intake was similar at various times before screening. These findings indicate that although diets high in beta-carotene may be associated with lower breast cancer risk, there does not seem to be evidence of a critical time period during which such diets are more relevant. (Epidemiology 1999;10:49–53)

ISSN:1044-3983    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Depression is associated with an increased risk of mortality in studies that included adults of all ages, but results of studies restricted to older adults are less consistent. This study evaluated the association between depressive symptoms and mortality among 764 white women aged 65+ years in Baltimore, Maryland, and examined methodologic and conceptual issues regarding this association. The Center for Epidemiologic Studies-Depression Scale (CES-D) was administered in face-to-face interviews in 1984. Mortality data were collected through 1990. The 6-year risk of death was 14.5% among women with CES-D scores of 0–1, 24% to 28% among women with scores of 2–24, and 47% among those with scores over 24. The adjusted hazards ratio (RR) comparing women with the highest (25–58)vslowest (0–1) scores was 1.77 (95% confidence interval (CI) = 0.91–3.42). Depressive symptoms were only weakly associated with mortality when using the CES-D scale dichotomized at the traditional cutpoint of 16 (RR = 1.10, CI = 0.73–1.66), or when the follow-up period was 2 years. Furthermore, depressive symptoms were associated with mortality only among women in poor health. The association between depressive symptoms and mortality risk appeared to be affected by baseline physical health, length of follow-up, and measurement of depression. (Epidemiology 1999;10:54–59)

ISSN:1044-3983    

出版商:OVID    

年代:1999

数据来源: OVID