Home About us Contact
|
Home About us Contact | ||
|
|
||
Reverse Causation (reverse + causation)
Selected AbstractsThe role of the intestinal microbiota in the development of atopic disordersALLERGY, Issue 11 2007J. Penders The prevalence of atopic diseases, including eczema, allergic rhinoconjunctivitis and asthma, has increased worldwide, predominantly in westernized countries. Recent epidemiological studies and experimental research suggest that microbial stimulation of the immune system influences the development of tolerance to innocuous allergens. The gastrointestinal microbiota composition may be of particular interest, as it provides an early and major source of immune stimulation and seems to be a prerequisite for the development of oral tolerance. In this review the observational studies of the association between the gut microbiota and atopic diseases are discussed. Although most studies indicated an association between the gut microbiota composition and atopic sensitization or symptoms, no specific harmful or protective microbes can be identified yet. Some important methodological issues that have to be considered are the microbiological methods used (traditional culture vs molecular techniques), the timing of examining the gut microbiota, the definition of atopic outcomes, confounding and reverse causation. In conclusion, the microbiota hypothesis in atopic diseases is promising and deserves further attention. To gain more insight into the role of the gut microbiota in the etiology of atopy, large-scale prospective birth cohort studies using molecular methods to study the gut microbiota are needed. [source] Mendelian randomization in nutritional epidemiologyNUTRITION REVIEWS, Issue 8 2009Lu Qi Nutritional epidemiology aims to identify dietary and lifestyle causes for human diseases. Causality inference in nutritional epidemiology is largely based on evidence from studies of observational design, and may be distorted by unmeasured or residual confounding and reverse causation. Mendelian randomization is a recently developed methodology that combines genetic and classical epidemiological analysis to infer causality for environmental exposures, based on the principle of Mendel's law of independent assortment. Mendelian randomization uses genetic variants as proxies for environmental exposures of interest. Associations derived from Mendelian randomization analysis are less likely to be affected by confounding and reverse causation. During the past 5 years, a body of studies examined the causal effects of diet/lifestyle factors and biomarkers on a variety of diseases. The Mendelian randomization approach also holds considerable promise in the study of intrauterine influences on offspring health outcomes. However, the application of Mendelian randomization in nutritional epidemiology has some limitations. [source] Reported pertussis infection and risk of atopy in 8- to 12-yr-old vaccinated and non-vaccinated childrenPEDIATRIC ALLERGY AND IMMUNOLOGY, Issue 1 2008Roos M. D. Bernsen Pertussis infection has been suspected to be a potential causal factor in the development of atopic disease because of the effect of pertussis immunization on specific IgE antibodies. Although several studies found a positive association between pertussis infection and atopic disorders, this relationship has not yet been studied in a population stratified by vaccination status. To assess the association between pertussis infection and atopic disorders in pertussis-unvaccinated children and in pertussis-vaccinated children. Using data from a previously conducted study on the relationship between the diphtheria-tetanus-pertussis-(inactivated) poliomyelitis vaccination in the first year of life and atopic disorders, the study population of 1872 8,12 yr old was divided into children pertussis-unvaccinated and children pertussis-vaccinated in the first year of life. Within each group, the association between pertussis infection and atopic disorders (both as reported by the parents) was assessed. In the unvaccinated group, there were no significant associations between pertussis infection and atopic disorders. In the vaccinated group, all associations between pertussis infection and atopic disorders were positive, the associations with asthma [odds ratio (OR) = 2.24, 95% confidence interval (CI95%): 1.36,3.70], hay fever (OR = 2.35, CI95%: 1.46,3.77) and food allergy (OR = 2.68, CI95%: 1.48,4.85) being significant. There was a positive association between pertussis infection and atopic disorders in the pertussis vaccinated group only. From the present study, it cannot be concluded whether this association is causal or due to reverse causation. [source] DO MARKETS PENALIZE AGENCY CONFLICTS BETWEEN CONTROLLING AND MINORITY SHAREHOLDERS?THE DEVELOPING ECONOMIES, Issue 3 2007EVIDENCE FROM CHILE G32; G34; O16 Using a sample of Chilean listed firms with widespread presence of economic conglomerates that use pyramid structures to control affiliated companies, we find that firms where controlling shareholders have higher coincidence between cash and control rights are persistently more valued by the market. We carefully check that our results are not driven by omitted variable biases and control for reverse causation using a feature of Chilean Corporations Law that provides an exogenous instrument for ownership concentration. [source] Bank Mergers and Crime: The Real and Social Effects of Credit Market CompetitionTHE JOURNAL OF FINANCE, Issue 2 2006MARK J. GARMAISE ABSTRACT Using a unique sample of commercial loans and mergers between large banks, we provide micro-level (within-county) evidence linking credit conditions to economic development and find a spillover effect on crime. Neighborhoods that experience more bank mergers are subject to higher interest rates, diminished local construction, lower prices, an influx of poorer households, and higher property crime in subsequent years. The elasticity of property crime with respect to merger-induced banking concentration is 0.18. We show that these results are not likely due to reverse causation, and confirm the central findings using state branching deregulation to instrument for bank competition. [source] | ||||||||||