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Relative Risk Estimates (relative + risk_estimate)
Selected AbstractsHealth-risk behaviours: examining social disparities in the occurrence of stillbirthPAEDIATRIC & PERINATAL EPIDEMIOLOGY, Issue 4 2008Jennifer Goy Summary While an association between low socio-economic status (SES) and increased risk of stillbirth has been observed consistently over several decades, the pathways through which SES exerts these effects have not been established. Given that some key health-risk behaviours for stillbirth, including smoking and pre-pregnancy obesity, have strong relationships with SES, health-risk behaviours may serve as a channel through which low SES contributes to stillbirth outcomes. The objective of this study was to estimate the proportion of the relationship between low SES and the occurrence of stillbirth that is explained by health-risk behaviours in populations of Eastern Ontario and Nova Scotia (112 stillbirth cases and 398 controls). Both area and individual level influences of SES were assessed. The study population consisted of 112 cases (women delivering stillborn infants) and 398 controls. Odds ratios and 95% confidence intervals estimated by multivariable logistic regression were used to approximate relative risks. The contribution of health-risk behaviours to relationships between SES and stillbirth was assessed by a change in the relative risk estimate following omission of each health-risk behaviour from the model. Of the three measures of individual level SES examined (household income, education, Blishen occupational index), only household income was a statistically significant predictor of stillbirth. After controlling for individual level SES, no community level SES effects were observed for stillbirth. Adjustments for key health-risk behaviours (smoking) resulted in an 18.5% reduction in the odds ratio estimate for low SES, from 3.31 to 2.79. This large unexplained SES effect that remained highlights the need for research into other potential pathways that may account for increased risk of stillbirth among those of lower SES. [source] Estimating haplotype relative risks in complex disease from unphased SNPs data in families using a likelihood adjusted for ascertainmentGENETIC EPIDEMIOLOGY, Issue 8 2006J. Carayol Abstract The understanding of complex diseases and insights to improve their medical management may be achieved through the deduction of how specific haplotypes may play a joint effect to change relative risk information. In this paper we describe an ascertainment adjusted likelihood-based method to estimate haplotype relative risks using pooled family data coming from association and/or linkage studies that were used to identify specific haplotypes. Haplotype-based analysis tends to require a large amount of parameters to capture all the information that leads to efficiency problems. An adaptation of the Stochastic Expectation Maximization algorithm is used for haplotypes inference from genotypic data and to reduce the number of nuisance parameters for risk estimation. Using different simulations, we show that this method provides unbiased relative risk estimates even in case of departure from Hardy-Weinberg equilibrium. Genet. Epidemiol. 2006. © 2006 Wiley-Liss, Inc. [source] Properties of case/pseudocontrol analysis for genetic association studies: Effects of recombination, ascertainment, and multiple affected offspringGENETIC EPIDEMIOLOGY, Issue 3 2004Heather J. Cordell Abstract The case/pseudocontrol approach is a general framework for family-based association analysis, incorporating several previously proposed methods such as the transmission/disequilibrium test and log-linear modelling of parent-of-origin effects. In this report, I examine the properties of methods based on a case/pseudocontrol approach when applied to a linked marker rather than (or in addition to) the true disease locus or loci, and when applied to sibships that have been ascertained on, or that may simply contain, multiple affected sibs. Through simulations and analytical calculations, I show that the expected values of the observed relative risk parameters (estimating quantities such as effects due to a child's own genotype, maternal genotype, and parent-of-origin) depend crucially on the ascertainment scheme used, as well as on whether there is non-negligible recombination between the true disease locus and the locus under study. In the presence of either recombination or ascertainment on multiple affected offspring, methods based on conditioning on parental genotypes are shown to give unbiased genotype relative risk estimates at the true disease locus (or loci) but biased estimates of population genotype relative risks at a linked marker, suggesting that the resulting estimates may be misleading when used to predict the power of future studies. Methods that allow for exchangeability of parental genotypes are shown (in the presence of either recombination or ascertainment on multiple affected offspring) to produce false-positive evidence of maternal genotype effects when there are true parent-of-origin or mother-child interaction effects, even when analyzing the true locus. These results suggest that care should be taken in both the interpretation and application of parameter estimates obtained from family-based genetic association studies. © 2004 Wiley-Liss, Inc. [source] Education and risk of breast cancer in the Norwegian-Swedish women's lifestyle and health cohort studyINTERNATIONAL JOURNAL OF CANCER, Issue 4 2004Tonje Braaten Abstract A positive relationship between level of education and female breast cancer risk is well supported by scientific evidence, but few previous studies could adjust for all relevant potential confounding factors. The authors' purpose was to examine how risk for breast cancer varies with level of education and to identify factors that explain this variation, using data from a prospective cohort study including 102,860 women from Norway and Sweden who responded to an extensive questionnaire in 1991/1992; 1,090 incident primary invasive breast cancer cases were revealed during follow-up, which ended in December 1999. The Cox Proportional Hazards Model was used to calculate relative risks (RR) with 95% confidence intervals (CI). Women with more than 16 years of education had a 36% increased risk compared to the lowest educated (7,9 years) (Age adjusted RR=1.36, 95% CI: 1.10, 1.68). This relationship was slightly stronger among postmenopausal (RR 1.51) than among premenopausal (RR 1.25) women. In both groups, however, the relative risk estimates turned close to unity by adjustment for parity, age at first birth, body mass index (BMI), height, age at menarche, menopausal status, use of oral contraceptives and consumption of alcohol. The overall multivariate relative risk among the highest educated women was 1.04 (95% CI 0.82,1.32). The results of our study suggest a clear positive gradient in risk for breast cancer by level of education, which can be fully explained by established breast cancer risk factors. © 2004 Wiley-Liss, Inc. [source] Exposure to furry pets and the risk of asthma and allergic rhinitis: a meta-analysisALLERGY, Issue 7 2008B. Takkouche Background:, Exposure to pets has been implicated as a risk factor for asthma. However, this relation has been difficult to assess in individual studies because of the large potential of selection bias. We sought to examine the association between exposure to furry pets and asthma and allergic rhinitis by means of a meta-analysis. Methods:, We retrieved studies published in any language by searching systematically Medline (1966,March 2007), Embase, LILACS and ISI Proceedings computerized databases, and by examining manually the references of the original articles and reviews retrieved. We included cohort and case,control studies reporting relative risk estimates and confidence intervals of exposure to cats, dogs and unspecified furry animals and subsequent asthma and allergic rhinitis. We excluded cross-sectional studies and those studies that did not measure exposure but rather sensitization to pets. Results:, Thirty-two studies were included. For asthma, the pooled relative risk related to dog exposure was 1.14 (95% CI 1.01,1.29), that related to exposure to any furry pet was 1.39 (95% CI 1.00,1.95). Among cohort studies, exposure to cats yielded a relative risk of 0.72 (95% CI 0.55,0.93). For rhinitis, the pooled relative risk of exposure to any furry pet was 0.79 (95% CI 0.68,0.93). Conclusions:, Exposure to cats exerts a slight preventive effect on asthma, an effect that is more pronounced in cohort studies. On the contrary, exposure to dogs increases slightly the risk of asthma. Exposure to furry pets of undermined type is not conclusive. More studies with exact measurement of exposure are needed to elucidate the role of pet exposures in atopic diseases. [source] Use of parenteral iron products and serious anaphylactic-type reactions,,§AMERICAN JOURNAL OF HEMATOLOGY, Issue 9 2010Diane K. Wysowski Controversy exists about the safety of the parenteral iron dextran products, Dexferrum and INFeD, which have been associated with rare, serious anaphylactic-type reactions. In the United States, their product labels carry boxed warnings of this adverse event; some have called for the withdrawal from marketing of the higher molecular weight Dexferrum. Between 2002 and 2007, sales of Dexferrum, INFeD, and iron gluconate Ferrlecit declined 32.5%, 21%, and 4.8%, respectively, while sales of iron sucrose Venofer increased 160%. Voluntary reports submitted to the Food and Drug Administration show anaphylactic reactions and symptoms for the four parenteral iron products. Because of underreporting, possible differential reporting, absence of iron dextran brand names, and incomplete use (denominator) data, incidence rates and relative risk estimates cannot be calculated. U.S. death certificate data show that for most years from 1979 through 2006, no more than 3 deaths per year were coded to "adverse events in therapeutic use of iron preparations;" brand names were not consistently recorded. Emergency department data show small numbers of visits for treatment of allergic reactions with intravenous iron preparations. The data presented herein show that allergic reactions are possible with all four parenteral iron products, and it is difficult to determine which product has the largest risk based on sales data, voluntarily submitted adverse event reports, death certificates, ED visits, and observational studies performed to date. To help differentiate risk among the parenteral iron products, the brand name of the product always should be provided on medical records, death certificates, and adverse drug reaction reports. Am. J. Hematol., 2010. Published 2010 Wiley-Liss, Inc. [source] Clearing the cervical spine in unconscious polytrauma victims, balancing risks and effective screeningANAESTHESIA, Issue 5 2004C. G. T. Morris Summary Cervical spine injury occurs in 5,10% of cases of blunt polytrauma. A missed or delayed diagnosis of cervical spine injury may be associated with permanent neurological sequelae. However, there is no consensus about the ideal evaluation and management of the potentially injured cervical spine and, despite the publication of numerous clinical guidelines, this issue remains controversial. In addition, many studies are limited in their application to the obtunded or unconscious trauma victim. This review will provide the clinician managing unconscious trauma victims with an assessment of the actual performance of clinical examination and imaging modalities in detecting cervical spine and isolated ligamentous injury, a review of existing guidelines in light of the available evidence, relative risk estimates and a proposed management scheme. [source] The Log Multinomial Regression Model for Nominal Outcomes with More than Two AttributesBIOMETRICAL JOURNAL, Issue 6 2007L. Blizzard Abstract An estimate of the risk or prevalence ratio, adjusted for confounders, can be obtained from a log binomial model (binomial errors, log link) fitted to binary outcome data. We propose a modification of the log binomial model to obtain relative risk estimates for nominal outcomes with more than two attributes (the "log multinomial model"). Extensive data simulations were undertaken to compare the performance of the log multinomial model with that of an expanded data multinomial logistic regression method based on the approach proposed by Schouten et al. (1993) for binary data, and with that of separate fits of a Poisson regression model based on the approach proposed by Zou (2004) and Carter, Lipsitz and Tilley (2005) for binary data. Log multinomial regression resulted in "inadmissable" solutions (out-of-bounds probabilities) exceeding 50% in some data settings. Coefficient estimates by the alternative methods produced out-of-bounds probabilities for the log multinomial model in up to 27% of samples to which a log multinomial model had been successfully fitted. The log multinomial coefficient estimates generally had lesser relative bias and mean squared error than the alternative methods. The practical utility of the log multinomial regression model was demonstrated with a real data example. The log multinomial model offers a practical solution to the problem of obtaining adjusted estimates of the risk ratio in the multinomial setting, but must be used with some care and attention to detail. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Reproductive factors and risk of breast carcinoma in a study of white and African-American women,,CANCER, Issue 2 2004Giske Ursin M.D., Ph.D. Abstract BACKGROUND Few studies have investigated the association between reproductive factors and the risk of breast carcinoma among African-American women. The authors assessed whether the number of full-term pregnancies, age at first full-term pregnancy, and total duration of breastfeeding were associated with similar relative risk estimates in white and African-American women in a large multicenter, population-based case,control study of breast carcinoma. METHODS Case patients were 4567 women (2950 white women and 1617 African-American women) ages 35,64 years with newly diagnosed invasive breast carcinoma between 1994 and 1998. Control patients were 4668 women (3012 white women and 1656 African-American women) who were identified by random-digit dialing and were frequency matched to case patients according to study center, race, and age. Adjusted odds ratios and 95% confidence intervals were estimated using unconditional logistic regression. RESULTS For white women, the reduction in risk of breast carcinoma per full-term pregnancy was 13% among younger women (ages 35,49 years) and 10% among older women (ages 50,64 years). The corresponding risk reductions for African-American women were 10% and 6%, respectively. Risk decreased significantly with increasing number of full-term pregnancies for both races and both age categories. Duration of lactation was inversely associated with breast carcinoma risk among younger parous white (trend P = 0.0001) and African-American (trend P = 0.01) women. African-American women tended to have more children compared with white women, but parity rates were lower in younger women than in older women in both racial groups. However, breastfeeding was substantially more common in young white women than in young African-American women. CONCLUSIONS Overall, parity and lactation had similar effects on breast carcinoma risk in white and African-American women. If younger African-American women now are giving birth to fewer children than in the past, without a substantial increase in breastfeeding, breast carcinoma rates may continue to increase at a more rapid rate among these women compared with white women. Cancer 2004. Published 2004 by the American Cancer Society. [source] | ||||||||||