ISSN:1044-3983    

出版商:OVID    

年代:1991

数据来源: OVID

ISSN:1044-3983    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

The incidence of acute appendicitis has been reported to vary substantially by country, geographic region, race, sex, season, and occupation, but the reasons for this variation are unknown. We evaluated several risk factors for appendicitis by analyzing data from hospital discharge abstracts on all cases of acute appendicitis treated surgically in nonfederal hospitals in California from 1983 to 1986 (N = 102,546). Comparison of age and sex-specific incidence rates for four racial/ethnic groups (white, Hispanic, black, and Asian/other) revealed rates in blacks and the Asian/other group one-half or less of the rates for whites and Hispanics between the ages of 5 and 29 years. Incidence rates in males were higher than rates in females in all racial/ethnic groups for most ages (RR = 1.1–1.7). Seasonal variation in incidence was modest. Peak rates occurred in July, August, and September, and the lowest rates occurred in December. Hypotheses about the etiology of appendicitis must account for substantial racial/ethnic, gender, age variation, and modest seasonal variation in theincidence

ISSN:1044-3983    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

In 1916, Sir Ronald Ross defined “dependent happenings” as events where the number affected in a unit of time depends on the number already affected. That is, the incidence depends on the prevalence, a characteristic of many infectious diseases. Because of this dependence, interventions against infectious diseases can have not only direct protective effects for the person receiving an intervention, but also indirect effects resulting from changes in the intensity of transmission in the population. This paper develops the conceptual framework for four types of study designs that differentiate and account for direct and indirect effects of intervention programs in dependent happenings

ISSN:1044-3983    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Probabilities that a patient will occupy any of five clinically defined compartments at different future times are generated and graphed by a personal computer. The probabilities are functions of a patient's relevant baseline characteristics (treated or control group), clinical status, and follow-up time at which the prognosis is made. The illustrative prognostic model is based on a reanalysis of detailed individual records for 81 patients with idiopathic membranous nephropathy (42 treated with methylprednisolone and chlorambucil; 39 controls) in a randomized clinical trial. The compartments to and from which patients may pass are identified as (1) complete remission, (2) partial remission, (3) the nephrotic syndrome, (4) renal failure, and (5) death. Estimated risk functions for transitions between compartments involve baseline treatment, and intermediate and temporal variables, together with their relevant interactions. The model illustrates how, despite the overall advantage of treated over control patients, the comparative prognoses can change greatly and can even sometimes be reversed, depending on a variety of follow-up experiences

ISSN:1044-3983    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Separate studies using data from the second National Health and Nutrition Examination Survey, 1976–1980 (NHANES II) have shown that blacks in the United States have higher blood lead levels than whites and that blood lead is positively related to blood pressure. Based on these reports, we examined data from NHANES II to determine the extent to which race differences in blood pressure were explained by elevated blood lead levels in blacks. Regression analyses, with race as an indicator variable, were used to estimate the contribution of blood lead to black-white differences in blood pressure. The overall effect of blood lead on race differences in blood pressure was small, reflecting, in part, the magnitude of race differences in blood lead and in the association of blood lead and blood pressure. Nevertheless, a pronounced and consistent effect of lead on race differences in blood pressure was found among the poor, particularly women

ISSN:1044-3983    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

The association between oral contraceptive use and breast cancer risk was examined using data from a case-control study of breast cancer in Long Island, New York. Cases were defined as female residents of Nassau and Suffolk Counties between the ages of 20 and 79, diagnosed with breast cancer between January 1, 1984 and December 31, 1986. Age- and county-matched controls were selected from driver's license files. Among all women under age 70 at diagnosis, there was no association between oral contraceptive use and breast cancer; there was, however, a positive association in the subgroup ages 20–49 (adjusted odds ratio = 1.68, 95% CI: 1.16–2.42). Risk increased with increasing duration of use, but did not differ between women who first used oral contraceptives before the first pregnancy and those who first used them later, or between women who first used oral contraceptives before age 25 and those who first used them at a later age. Risk also appeared to increase with number of years of use before the first pregnancy or before age 25, although numbers were small. History of benign breast disease did not influence risk. The association of breast cancer risk with oral contraceptive use appeared stronger in women from Suffolk County than Nassau County

ISSN:1044-3983    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

This paper describes a method and associated computer program for calculating exact confidence limits and P values, along with the conditional maximum likelihood estimate of the common odds ratio for a series of 2 × 2 tables. The program can be used to calculate exact estimates for matched data and is considerably faster than others currently available

ISSN:1044-3983    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Other authors have shown how to estimate attributable risk based on stratification. In this paper, we show how to estimate adjusted attributable risks, standard errors, and confidence intervals from an unmatched case-control study that has population-based controls and uses the logistic regression model to estimate relative risk. We apply the method to data from a case-control study of low birthweight. The method is conceptually simple, has no assumptions beyond those of the logistic model, makes use of computer-intensive statistical techniques (the bootstrap), and extends to interactions. A Fortran computer program to carry out the computations is available from the authors upon request

ISSN:1044-3983    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

The rules to assess causation formulated by the eighteenth century Scottish philosopher David Hume are compared to Sir Austin Bradford Hill's causal criteria. The strength of the analogy between Hume's rules and Hill's causal criteria suggests that, irrespective of whether Hume's work was known to Hill or Hill's predecessors, Hume's thinking expresses a point of view still widely shared by contemporary epidemiologists. The lack of systematic experimental proof to causal inferences in epidemiology may explain the analogy of Hume's and Hill's, as opposed to Popper's, logic

ISSN:1044-3983    

出版商:OVID    

年代:1991

数据来源: OVID