摘要:

Background.Acute urinary tract infection is one of the most common infections seen in primary care.Methods.We conducted a nested case-control study among a cohort of 519 women, ages 15–29 years, enrolled in a contraceptive acceptability study to examine whether recent use of male condoms increases urinary tract infection risk.Results.One hundred sixty-five incident urinary tract infections were identified during 12-month follow-up periods in a cohort study that was conducted between 1996 and 1999. After exclusions for urinary tract infection recurrences, pregnancy, antibiotic use, diabetes, diaphragm/cervical cap use, or urinary tract abnormalities, there were 100 cases and 200 controls. Compared with women not using barrier methods (and after adjustment for age, urinary tract infection history, hormonal method use, and frequency of sex) the odds ratio (OR) for any reported use of condoms coated with spermicide (Nonoxynol-9) in the previous 30 days was 2.8 (95% [confidence interval] CI = 1.2–6.5). The OR was 11.5 (95% CI = 2.5–53) for exclusive Nonoxynol-9–coated condom use. The OR for exclusive use of non-Nonoxynol-9–coated condoms was 7.4 (95% CI = 1.6–35).Conclusions.In this study, use of male condoms was associated with increased urinary tract infection risk; the largest risk was associated with exclusive condom use and use of Nonoxynol-9–coated condoms.

ISSN:1044-3983    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background.Nonresponse bias is a concern in any epidemiologic survey in which a subset of selected individuals declines to participate.Methods.We reviewed multiple imputation, a widely applicable and easy to implement Bayesian methodology to adjust for nonresponse bias. To illustrate the method, we used data from the Canadian Multicentre Osteoporosis Study, a large cohort study of 9423 randomly selected Canadians, designed in part to estimate the prevalence of osteoporosis. Although subjects were randomly selected, only 42% of individuals who were contacted agreed to participate fully in the study. The study design included a brief questionnaire for those invitees who declined further participation in order to collect information on the major risk factors for osteoporosis. These risk factors (which included age, sex, previous fractures, family history of osteoporosis, and current smoking status) were then used to estimate the missing osteoporosis status for nonparticipants using multiple imputation. Both ignorable and nonignorable imputation models are considered.Results.Our results suggest that selection bias in the study is of concern, but only slightly, in very elderly (age 80+ years), both women and men.Conclusions.Epidemiologists should consider using multiple imputation more often than is current practice.

ISSN:1044-3983    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background.Previous cohort studies have found an elevated risk of lung cancer among rock and slag wool (RSW) production workers. The aim of the present study was to investigate the risk of lung cancer associated with exposure to RSW while controlling for other occupational exposures and tobacco smoking.Methods.Since 1971, a total of 196 lung cancer cases occurred among men who worked in seven plants in Denmark, Norway, Sweden, and Germany, with start of production between 1937 and 1950. We obtained information on occupational history and extra-occupational factors from either the subject or the next of kin for 133 cases and 513 matched controls. We assessed occupational exposure on the basis of interview data combined with information from expert panels set up in each factory.Results.For cumulative exposure to RSW assessed with a 15-year lag, the smoking-adjusted odds ratios in the second, third, and fourth quartiles of exposure were 1.3 (95% confidence interval [CI] = 0.7–2.3), 1.0 (CI = 0.5–1.9), and 0.7 (CI = 0.3–1.3). Similar results were obtained when we included only those workers employed for more than 1 year, when we included other indicators of RSW exposure, and after control for co-exposures.Conclusions.This study provides no evidence of a carcinogenic effect on the lung of rock and slag wool under exposure circumstances in the production industry during the last four to five decades.

ISSN:1044-3983    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background.The ubiquitous dichlorodiphenyltrichloroethane (DDT) metabolite 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) is an androgen receptor antagonist. Data on potential antiandrogenic activity of DDE in humans are limited.Methods.The relations between concentrations of plasma DDE and several serum androgens (total testosterone, bioavailable testosterone, 5&agr;-dihydrotestosterone, and free androgen index) were examined in 137 North Carolina black male farmers, using multiple linear regression.Results.Participants ranged in age from 30 to 88 years (mean = 62 years). Most had farmed for about 30 years and 27% reported having used DDT. The median DDE level was 7.7 &mgr;g per liter (1213 &mgr;g per kg lipid), slightly higher than in other recent studies. Overall, concentrations of DDE and androgens were unrelated. Total testosterone decreased 2% (95% confidence limits [CL] = −9%, 5%) per increase in interquartile distance of lipid-adjusted DDE. The percentage change in other hormones was similarly negligible. However, among those whose DDE level was in the top tenth percentile, compared with all others, total testosterone and free androgen index were lower by 23% (CL= −40%, 1%) and 22% (CL =−41%, 4%) respectively. Plasma androgen levels decreased with age, a relation that has previously been studied only in whites.Conclusions.Studies of more highly exposed populations may be needed to evaluate effects, if any, of DDE.

ISSN:1044-3983    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Partially ecologic case-control studies combine group-level exposure data with individual-level data on disease status, group membership, and covariates. If the exposure measure is the exposure prevalence of various groups, the attributable fraction (AF; the estimated proportion of cases that are attributable to exposure) can be estimated by classifying all subjects in groups with exposure prevalence above zero as exposed. Such a threshold AF estimator (FIGURET) is unbiased in confounding-free situations if the threshold is 100% sensitive, but it might be imprecise. We propose an alternative AF estimator,FIGUREL, for partially ecologic case-control studies under a linear model for the association between the exposure prevalence and the odds ratio. The proposed estimator can also be applied to situations in which covariate adjustment is necessary.FIGURETandFIGURELare compared with respect to precision and bias.FIGURELis also unbiased when the exposure prevalence is zero in the group(s) assessed as unexposed. UsingFIGURELwill consistently result in improved precision compared withFIGURET, although the results may not differ substantially. The 95% confidence intervals for both AF estimators show satisfactory coverage in bias-free exposure scenarios. Pronounced negative bias and decreased coverage result for both AF estimators even when small fractions (3–9%) of exposed subjects are included in the group assessed as unexposed.Figure. No caption available.Figure. No caption available.Figure. No caption available.Figure. No caption available.Figure. No caption available.Figure. No caption available.Figure. No caption available.

ISSN:1044-3983    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background.The association between cigarette smoking and ovarian cancer may vary according to the histologic type of tumor.Methods.We examined cigarette smoking as a risk factor for both mucinous and nonmucinous tumors in a population-based case-control study comparing 767 incident cases of epithelial ovarian cancer with 1,367 community controls frequency matched to cases by age and race.Results.Smoking was associated with mucinous tumors (odds ratio [OR] = 1.9; 95% confidence interval [CI] = 1.3–2.9) but not with nonmucinous tumors (OR = 1.1; CI = 0.9–1.3). Furthermore, the odds ratios for smokers with mucinous tumors increased with increasing pack-years of smoking (OR = 1.0, 1.9, and 2.7 for <5, 5–24, and > 24+ pack-years, respectively;Pfor trend = 0.01)Conclusions.Cigarette smoking appears to be a risk factor for mucinous but not for nonmucinous tumors.

ISSN:1044-3983    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:1044-3983    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background.As information about the health risks associated with air pollution has become available, attention has focused increasingly on susceptible persons such as children and persons with preexisting respiratory diseases, such as asthma.Methods.We investigated the association between outdoor air pollution and asthma attacks among children under 15 years of age in Seoul, Korea. We estimated the relative risks of hospitalization associated with an interquartile range (IQR) increase in pollutant concentrations and used time series analysis of the counts by means of the generalized additive Poisson model.Results.The estimated relative risk of hospitalization for asthma was 1.07 (95% confidence interval [CI] = 1.04–1.11) for particulate matters less than or equal to 10 &mgr;m in aerodynamic diameter (IQR = 40.4 &mgr;g/m3); 1.11 (95% CI = 1.06–1.17) for sulfur dioxide (IQR = 4.4 ppb); 1.15 (95% CI = 1.10–1.20) for nitrogen dioxide (IQR = 14.6 ppb); 1.12 (95% CI = 1.07–1.16) for ozone (IQR = 21.7 ppb); and 1.16 (95% CI = 1.10–1.22) for carbon monoxide (IQR = 1.0 ppm).Conclusions.These findings support the hypothesis that air pollution at levels below the current standards of Korea is harmful to sensitive subjects such as asthmatic children.

ISSN:1044-3983    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background.Multivitamin use has been associated with lower risks for some birth defects. We evaluated whether multivitamin use modified birth defect risks associated with febrile illness, a common and possibly teratogenic exposure.Methods.From the population-based Atlanta Birth Defects Case-Control Study (1968–1980) we selected seven defects (neural tube defects, cleft lip and palate, cardiac outflow tract defects, ventricular septal defects, atrial septal defects, omphalocele, and limb deficiencies) because of their inverse relation with multivitamin supplement use documented in previous analyses. We defined four exposure categories from combinations of multivitamin use (periconceptional use compared with no use) and febrile illness (early pregnancy compared with no illness). The reference category was no multivitamin use and no illness.Results.Febrile illness with no multivitamin use was associated with generally increased risk for the seven defects and the combined group (odds ratio = 2.1, 1.7, 1.5, 1.9, 2.9, 4.4, 3.3, and 2.3, respectively). With multivitamin use, however, the risk estimates associated with febrile illness were generally lower (odds ratio = 0.6, 1.1, 0.0, 1.5, 0.0, 0.8, 0.0, and 0.8, respectively). Some of the associated 95% confidence intervals included one.Conclusions.The pattern of findings suggests that multivitamin use might decrease the risk associated with febrile illness.

ISSN:1044-3983    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:1044-3983    

出版商:OVID    

年代:2002

数据来源: OVID