摘要:

Flavonols and flavones are antioxidant polyphenolic compounds found in tea, vegetables, fruits, and wine. In experimental studies they have been effective free radical scavengers, metal chelators, and antithrombotic agents. In the few epidemiologic studies of these agents, some have suggested an inverse association between intake of flavonols and flavones and the risk of cardiovascular disease. Our study population comprised 25,372 male smokers, 50–69 years of age, with no previous myocardial infarction. They were participants of the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study, which was a randomized, double-blind, placebo-controlled trial with daily supplementation of alpha-tocopherol (50 mg per day) and/or beta-carotene (20 mg per day). The men completed a validated dietary questionnaire at baseline. After 6.1 years of follow-up, there were 1,122 nonfatal myocardial infarctions and 815 coronary deaths. In the multivariate model, the relative risk of nonfatal myocardial infarction was 0.77 (95% confidence interval = 0.64–0.93) among men in the highest (median 18 mg per day) compared with the lowest (median 4 mg per day) quintile of flavonol and flavone intake. The respective relative risk for coronary death was 0.89 (95% confidence interval = 0.71–1.11). Thus, intake of flavonols and flavones was inversely associated with nonfatal myocardial infarction, whereas there was a weaker association with coronary death.

ISSN:1044-3983    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

The period before the first birth is traditionally viewed as particularly critical for a woman’s breast cancer risk. Nonetheless, the importance of early timing of a woman’s first compared with subsequent births is not well understood. In the present study we examine this question using a population-based cohort of 1.5 million Danish women born between 1935 and 1978. Between 1968 and 1994, 13,049 incident cases of breast cancer were identified in the Danish Cancer Registry. According to our results, a woman’s breast cancer risk is related to her age at any of her births. The risk increase per 5 year’s increase in maternal age at first, second, third, and fourth birth was 9%, 7%, 5%, and 14%, respectively. For fifth and sixth births it was 5%. We observed a risk reduction after any birth occurring before 30 years of age (in uniparous women before 25 years of age). These effects were strongest more than 10 years after birth. Thus, our study shows that early timing of any additional birth induces an additional long-term reduction in maternal risk of breast cancer; that is, early reproductive years, rather than just the nulliparous years, constitute the critical period.

ISSN:1044-3983    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Irregular working hours, including working at night, have serious psychological and physiological effects. In a nationwide population-based case-control study, we investigated the breast cancer risk among 30- to 54-year-old Danish women who worked predominantly at night. Individual employment histories were reconstructed back to 1964 for each of 7035 women with breast cancer and their individually matched controls from the records of a nationwide pension scheme with compulsory membership. Odds ratios, including 5 years of induction time and adjusted for socio-economic status, age at the birth of first and last child and number of children, were estimated by conditional logistic regression analysis. The odds ratio for breast cancer among women who worked at night at least half of a year was 1.5 (95% confidence interval, 1.2 to 1.7), and there was a tendency to increasing odds ratio by increasing duration of nighttime employment.

ISSN:1044-3983    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

We conducted a population-based, case-control study on hematolymphopoietic malignancies in 12 areas in Italy to investigate associations between different hematolymphopoietic malignancies and exposure to solvents and pesticides. We collected all incident cases 20–74 years of age from 12 areas, with a combined population of approximately 7 million residents. The control group was formed by a random sample of the study population. Data presented in this paper refer to 2,737 interviewed cases of 3,357 eligible cases and to 1,779 of 2,391 eligible controls. We analyzed risks associated with occupation using job-title information to evaluate disease pattern according to job category. An earlier publication presented results for women; here, we report the findings for men and discuss the overall patterns in both genders. The most consistent overall finding was an approximate doubling in relative risk for all four types of malignancies among male managers and related occupations. Several additional occupations were associated with elevated risk of one or more malignancies among men. These included cooks, waiters, and bartenders, and building caretakers and cleaners, for non-Hodgkin’s lymphoma; textile workers and machinery fitters for Hodgkin’s lymphoma; metal processors, material handlers, rubber workers, and painters for leukemia; and hairdressers, metal processors, tailors, electrical workers, and plumbers for multiple myeloma. The finding of increased risk of non-Hodgkin’s lymphoma among both male and female cooks, waiters, and bartenders has not been previously reported; nor has the elevated risk of leukemia among material handlers. Among people engaged in agriculture, those employed as tractor drivers and as “orchard, vineyard, and related tree and shrub workers” appeared to be at increased risk for hematolymphopoietic malignancies.

ISSN:1044-3983    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Use of nonsteroidal antiinflammatory drugs (NSAIDs) has been associated with a reduced risk of colorectal cancer, but limited information is available on the effect of individual nonaspirin NSAIDs. In addition, the dose-response relation of aspirin in reducing the risk of colorectal cancer has not been described. We carried out a population-based cohort study with secondary case-control analysis to determine the association between the risk of colorectal cancer and use of aspirin and individual NSAIDs, including the role of dose and duration. The General Practice Research Database in the U.K. was the source population. We traced 943,903 persons 40–79 years of age and free of cancer and colorectal adenoma between January 1994 and September 1997. A total of 2,002 incident cases of colorectal cancer were ascertained. The incidence rate of colorectal cancer per 10,000 person-years was 7.3. The risk of colorectal cancer was reduced in users of nonaspirin NSAIDs and became evident after 6 months of continuous treatment. The adjusted relative risk was 0.5 (95% confidence interval = 0.4–0.7). The reduction in risk disappeared completely 1 year after stopping NSAID treatment. The risk of developing colorectal cancer was reduced in long-term users of aspirin at doses of 300 mg daily (relative risk = 0.6; 95% confidence interval = 0.4–0.9). Daily doses of 75 and 150 mg aspirin were not associated with a reduced risk of colorectal cancer. Our data support the existence of an important protective effect of nonaspirin NSAID continuous intake against colorectal cancer and point to a similar reduction in risk for aspirin at doses of at least 300 mg daily. One-year treatment with NSAIDs would prevent one case of colorectal cancer in a population of 1,000 persons 70–79 years of age.

ISSN:1044-3983    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Prospective studies evaluating risk factors for abdominal aortic aneurysm are few. We studied the association of life-style factors with risk for abdominal aortic aneurysm among 29,133 male smokers 50–69 years of age, participants in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. During a mean follow-up of 5.8 years, 181 were diagnosed with ruptured abdominal aortic aneurysm or nonruptured abdominal aortic aneurysm plus aneurysmectomy. Risk for abdominal aortic aneurysm was positively associated with age [relative risk (RR) = 4.56, 95% confidence interval (CI) = 2.42–8.61 for >65vs≤55 years], smoking years (RR = 2.25, 95% CI = 1.33–3.81 for >40vs≤32 years), systolic blood pressure (RR = 1.92, 95% CI = 1.13–3.25 for >160vs≤130 mmHg), diastolic blood pressure (RR = 1.80, 95% CI = 1.05–3.08 for >100vs≤85 mmHg), and serum total cholesterol (RR = 1.85, 95% CI = 1.09–3.12 for >6.5vs≤5.0 mmol/liter). High-density lipoprotein cholesterol showed a strong inverse association with risk for aortic aneurysm (RR = 0.16, 95% CI = 0.08–0.32 for >1.5vs≤ 0.9 mmol/liter). High energy intake was associated with lower risk for aortic aneurysm (RR = 0.59, 95% CI = 0.38–0.94 for the highest quartilevsthe lowest), whereas no associations with nutrients were evident. We conclude that classical risk factors for atherosclerotic diseases seem to be important in pathogenesis of large abdominal aortic aneurysms.

ISSN:1044-3983    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Frequency matching can be used to increase the precision and power of case-control studies. Unmatched and frequency-matched designs are only two distinct possibilities of control selection in a continuum regarding the frequency of the matching factor in controls. We assessed the power and efficiency of case-control studies under a variety of assumptions regarding the prevalence and the effects of the matching factor and the exposure of interest as well as their association in the population. For each set of parameters, we simulated 10,000 case-control studies varying the degree of matching, that is, the proportion of the matching factor in selected controls over a wide range including the proportion in cases (matched design) and the population (unmatched design) as two special options. Traditional frequency matching increased the precision and power in most scenarios, but most of the gain was often achieved by incomplete (less than perfect) matching. Even greater gains were sometimes observed by increasing the prevalence of the matching factor in controls above the one in cases. In the scenarios assessed, perfect matching was neither necessary nor the optimum degree of matching in many circumstances. It might be worthwhile to evaluate the optimum degree of matching for specific settings in the design of case-control studies.

ISSN:1044-3983    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

A recent report from the Institute of Medicine recommends more methodologic and substantive research on the health of lesbians. This study addresses one methodologic topic identified in the Institute of Medicine report and by a subsequent scientific workshop on lesbian health: the definition and assessment of sexual orientation among women. Data are from the Women Physicians’ Health Study, a questionnaire-based U.S. probability sample survey (N = 4,501). The two items on sexual orientation (current self-identity and current sexual behavior) had a high response rate (96%), and cross-tabulation of responses indicated several combinations of identity and behavior. Three conceptually different definitions of “lesbian” are compared on the basis of (1) identity only, (2) sexual behavior only, and (3) both identity and sexual behavior. Suggestions and cautions are given to researchers who will add items on sexual orientation to new or ongoing research on women’s health.

ISSN:1044-3983    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

A risk ratio or difference from a meta-analysis is as many as ten steps away from the unobservable causal risk ratios and differences in target populations. The steps are like lenses, filters, or other fallible components of the epidemiologist’s “telescope” for observing populations. Each step is another domain where different biases can be caused. How biases combine across domains in the production of epidemiologic evidence can be quickly explained to nonepidemiologists by using a sequence of causal arrow diagrams with easy notation: (a) agent of interest, (b) background risk factors, (c) correlated causes, (d) diagnosis, (e) exposure measurement, (f) filing of data, (g) grouping of cohorts, (h) harvesting of cases and controls, (i) interpretations of investigators, (j) judgments of journals, and (k) knowledge of meta-analysts. For epidemiologists, this article serves as a review of ideas about confounding, information bias, and selection bias and underscores the need for routinely analyzing the sensitivity of study findings to multiple hypothesized biases.

ISSN:1044-3983    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Studies have suggested that offspring of women hospitalized for hyperemesis gravidarum have a different sex ratio than those of women without this diagnosis, but little is known of the potential association between fetal gender and variables such as severity of hyperemesis, gestational trimester, and maternal age. Our findings provide evidence that pregnant women with a diagnosis of hyperemesis gravidarum in the first trimester give birth to a higher proportion of female newborns than do all mothers, regardless of whether they are hospitalized.

ISSN:1044-3983    

出版商:OVID    

年代:2001

数据来源: OVID