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At least 1,639 records · Page 91Linked to original sources
PubMed1998

[Oral contraceptives and breast cancer--a causal relationship?].

Concern about the relationship between oral contraceptives, which have been used by more than 200 million women, and the risk of breast cancer has been present since three decades. Early studies showed no consistent results, but some authors are concerned about several subgroups having possibly an increased risk of developing breast cancer. A meta-analysis representing 90% of the data available on the topic showed a small but significant increase in the relative risk of developing breast cancer in women currently using oral contraception (1.24). This risk decreases after oral contraceptives have been ceased (1.16-1.07) and is comparable after 10 years to that of controls.

Adolescent↗
PubMed1989

Ambulatory care use among the noninstitutionalized elderly. A causal model.

While it is recognized that need for care is the dominant factor influencing utilization of health services, little is known regarding the determinants of ambulatory care use by the noninstitutionalized elderly. It is important to examine the relationships among need factors and how physical and mental dysfunctions influence use of services. This study uses a LISREL model to identify the extent to which ambulatory care use was affected by physical or mental functioning and whether strong linkages would be exhibited by both factors.

Aged↗
PubMed2007

Promising new causal explanations for obesity and obesity-related diseases.

Current explanations for obesity center around a predisposition in genotype and phenotype, possibly triggered by an inflammatory process or event, and exacerbated by environmental and psychological factors. It is likely that a variety of physiologic factors may act in combination to produce clinical obesity. Leptin resistance may be an important neurochemical cause of obesity; elevated leptin levels have been correlated with weight gain over extended time periods. Genetic studies support the postulate that a gene originating with our cave-dwelling ancestors, critical to survival when food was scare, has evolved into a trigger for obesity and related diseases. A variety of biochemical markers are prevalent in obesity and obesity-linked disease states. C-reactive protein, interleukin-6, and others are elevated in obesity, supporting the hypothesis that inflammation plays a role in the condition. Tumor necrosis factor-alpha is overexpressed in obesity and diabetes, suggesting that it may be part of the link between the 2 conditions.

Appetite↗
PubMed2006

Development and validation of MIX: comprehensive free software for meta-analysis of causal research data.

BACKGROUND: Meta-analysis has become a well-known method for synthesis of quantitative data from previously conducted research in applied health sciences. So far, meta-analysis has been particularly useful in evaluating and comparing therapies and in assessing causes of disease. Consequently, the number of software packages that can perform meta-analysis has increased over the years. Unfortunately, it can take a substantial amount of time to get acquainted with some of these programs and most contain little or no interactive educational material. We set out to create and validate an easy-to-use and comprehensive meta-analysis package that would be simple enough programming-wise to remain available as a free download. We specifically aimed at students and researchers who are new to meta-analysis, with important parts of the development oriented towards creating internal interactive tutoring tools and designing features that would facilitate usage of the software as a companion to existing books on meta-analysis. RESULTS: We took an unconventional approach and created a program that uses Excel as a calculation and programming platform. The main programming language was Visual Basic, as implemented in Visual Basic 6 and Visual Basic for Applications in Excel 2000 and higher. The development took approximately two years and resulted in the 'MIX' program, which can be downloaded from the program's website free of charge. Next, we set out to validate the MIX output with two major software packages as reference standards, namely STATA (metan, metabias, and metatrim) and Comprehensive Meta-Analysis Version 2. Eight meta-analyses that had been published in major journals were used as data sources. All numerical and graphical results from analyses with MIX were identical to their counterparts in STATA and CMA. The MIX program distinguishes itself from most other programs by the extensive graphical output, the click-and-go (Excel) interface, and the educational features. CONCLUSION: The MIX program is a valid tool for performing meta-analysis and may be particularly useful in educational environments. It can be downloaded free of charge via http://www.mix-for-meta-analysis.info or http://sourceforge.net/projects/meta-analysis.

Causality↗
PubMed2025

Causal association between non-steroidal anti-inflammatory drugs use and the risk of benign prostatic hyperplasia: a univariable and multivariable Mendelian randomization study.

BACKGROUND: The results of earlier observational research on the relationships between the usage of non-steroidal anti-inflammatory medicines (NSAIDs) and the risk of benign prostatic hyperplasia (BPH) have been inconsistent. METHODS: To assess these associations, we performed both univariable and multivariable Mendelian randomization (MR) studies. Instrumental variables (IVs) associated with exposures at the significance level (p&#x2009;<&#x2009;5&#x2009;&#xd7;&#x2009;10-6) were selected from a comprehensive meta-analysis conducted by the United Kingdom Biobank (UKB). Summary data for BPH were obtained from the FinnGen consortium, which comprised 30,066 cases and 119,297 controls. Sensitivity analyses were performed to evaluate heterogeneity and pleiotropy. RESULTS: We found evidence by univariable MR (UVMR) that genetically predicted NSAIDs use increased the risk of BPH (odds ratio [OR] per unit increase in log odds NSAIDs use: 1.164, 95% confidence interval [CI]: 1.041-1.302, p&#x2009;=&#x2009;0.008). After controlling for inflammation in multivariable MR (MVMR), the link persisted (OR: 1.165, 95% CI: 1.049-1.293, p&#x2009;=&#x2009;0.004). There were no indications of potential heterogeneity and pleiotropy in UVMR and MVMR analyses. CONCLUSION: The results of the MR estimates suggest that genetically predicted NSAIDs use may elevate the risk of BPH. This outcome prompts the imperative for deeper exploration into potential underlying mechanisms.

Humans↗
PubMed2004

Sensitivity analysis of causal inference in a clinical trial subject to crossover.

In many clinical trials it is possible for some subjects to cross over between treatment arms. One can evaluate the effect of crossover by modeling it as a missing-data problem, where for subjects who cross over, one treats the unobserved value of the outcome in the original randomization arm as the missing data. The as-treated analysis is invalid if the crossover is nonignorable, in the sense that the crossovers represent a nonrandom sample of the randomized subjects. A recent area of general interest is the development of methods for measuring the sensitivity of inferences to nonignorability in the missing-data mechanism; one such approach is that of Troxel et al. In this paper we apply their method to the problem of measuring sensitivity to nonignorable crossover in randomized trials, extending it to the case where the crossover mechanism may differ between arms. Our method allows us to identify circumstances under which the as-treated analysis may be more or less sensitive to nonignorable crossover. We illustrate it with the example of a randomized clinical trial (RCT) in multiple sclerosis and a study of the effect of military service on income.

Causality↗
PubMed2001

No benefit of the doubt: intergroup bias in understanding causal explanation.

Conversational conventions predict that receivers weigh later information more heavily than earlier information because they presume that communicators add later information only when it is particularly relevant and important. Drawing on Pettigrew's observation of the ultimate attribution error, the present research predicted that intergroup bias could override this conversational convention when individuals received multiple explanations (one beneficial, one condemning) for acts committed by out-group members vs. in-group members. Specifically, subsequently presented mitigating explanations for negative acts should not temper impressions of out-group members, and subsequently presented crediting explanations for positive acts should not enhance impressions of out-group members. Results supported this pattern, and the discussion considers these findings in light of communication rules, and in-group/out-group definition.

Analysis of Variance↗
PubMed2004

Causality assessment in drug-induced hepatotoxicity.

Drugs are currently an important cause of liver disease, ranked as the most frequent reason for acute liver failure. Despite recent advances in knowledge of the mechanisms implicated in drug-induced hepatocellular damage and cholestasis, as well as the identification of several risk factors, the diagnosis of hepatotoxicity remains a difficult task because specific tests are not available. In a step-by-step approach, the incrimination of a drug in liver symptoms requires a high degree of suspicion on the part of the physician, temporal eligibility, awareness of the drug's hepatotoxic potential, the exclusion of alternative causes of liver damage, and the ability to detect the presence of subtle data that favour a toxic aetiology. Ultimately, the use of diagnostic algorithms may add consistency to the diagnostic process either by translating the suspicion into a quantitative score or by providing a framework that emphasises the features that merit attention in cases of suspected hepatic adverse reactions.

Adult↗
PubMed2004

Thimerosal exposure in infants and developmental disorders: a prospective cohort study in the United kingdom does not support a causal association.

OBJECTIVE: There is an established link between exposure to mercury and impaired childhood cognitive development and early motor skills. Thimerosal (also known as thiomersal), a preservative used in a number of children's vaccines, contains ethylmercury (an organic compound of mercury), and there has been concern that this exposure to mercury may be of some detriment to young children. The aim of this research was to test in a large United Kingdom population-based cohort whether there is any evidence to justify such concerns. METHODS: We used population data from a longitudinal study on childhood health and development. The study has been monitoring >14,000 children who are from the geographic area formerly known as Avon, United Kingdom, and were delivered in 1991-1992. The age at which doses of thimerosal-containing vaccines were administered was recorded, and measures of mercury exposure by 3, 4, and 6 months of age were calculated and compared with a number of measures of childhood cognitive and behavioral development covering the period from 6 to 91 months of age. RESULTS: Contrary to expectation, it was common for the unadjusted results to suggest a beneficial effect of thimerosal exposure. For example, exposure at 3 months was inversely associated with hyperactivity and conduct problems at 47 months; motor development at 6 months and at 30 months; difficulties with sounds at 81 months; and speech therapy, special needs, and "statementing" at 91 months. After adjustment for birth weight, gestation, gender, maternal education, parity, housing tenure, maternal smoking, breastfeeding, and ethnic origins, we found 1 result of 69 to be in the direction hypothesized-poor prosocial behavior at 47 months was associated with exposure by 3 months of age (odds ratio: 1.12; 95% confidence interval: 1.01-1.23) compared with 8 results that still supported a beneficial effect. CONCLUSIONS: We could find no convincing evidence that early exposure to thimerosal had any deleterious effect on neurologic or psychological outcome.

Animals↗