Causal Relationship Between Acromegaly and Colon Cancer: A Two-sample Mendelian Randomization Study / 肿瘤防治研究

Objective To determine the causal relationship between acromegaly and colon cancer by using two-sample Mendelian randomization. Methods Genetic loci closely related to acromegaly in the whole genome-wide association study (GWAS) were selected as tool variables, and the genetic data of colon cancer from different GWASs were analyzed by two-sample Mendelian randomization (MR).The inverse variance weighting method (IVW) of the random effect model was used for analysis, and MR-weighted median and MR-Egger methods were used to supplement the analysis. Results were presented as OR values. Results Four SNPs closely related to acromegaly were obtained as tool variables, and the multiplicity test of tool variables showed that P=0.59.Three methods were used to estimate causal effects.The IVW analysis were OR=1.00(0.99-1.001) and P=0.42;the MR-Egger analysis results were OR=1.00(0.99-1.001) and P=0.42;and the Weighted median analysis results were OR=1.00(1.00-1.001) and P=0.03.The sensitivity test showed that the confidence interval of the tool variable SNP passed through 0, indicating the robustness of the MR results. Conclusion Acromegaly is not an independent risk factor for colon cancer.

A mendelian randomization study of the causal association between gastroesophageal reflux and atrial fibrillation / 公共卫生与预防医学

Objective In this study，we performed two sampie Mendelian Randomization to infer a causal association between Gastroesophageal reflux(GERD) and Atrial fibrillation(AF)，it can effectively avoid the problems such as reverse causation and confounds in traditional epidemiology. Methods We used the Summary data of GERD and AF from published Genome wide association study(GWAS) of European Individuals. Single Nucleotide Polymorphisms (SNPs) were extracted as Instrumental Variables (IVs).The main MR methods include Inverse Variance [] Weighted(IVW)，Weighted Median(WME)，MR-Egger，Simple Mode，and Weighted Mode.In addition，we used the sensitivity analysis such as MR-PRESSO，Cochran's Q test etc. Results The IVW shows a causal association between GERD and AF(P<0.0001，OR=1.16，95%CI:1.10-1.23).The WME shows P＜0.0001，OR=1.20，95%CI:1.11-1.30；Simple Mode shows P=0.01，OR=1.34，95%CI:1.07-1.69；Weighted Mode shows P=0.02，OR=1.33，95%CI:1.06-1.66. Conclusion This study based on genetic data supports the causal association between GERD and AF. The occurrence of GERD could increase the risk of AF.

Association of ticagrelor with risk of infection：a two-sample Mendelian randomization study based on the GWAS database / 中国药房

OBJECTIVE To investigate the causal association between ticagrelor and risk of infection METHODS Two-sample Mendelian randomization was adopted. Genetic instrumental variables were selected based on the results of the largest genome-wide association analysis to in vivo exposure of ticagrelor and its major active metabolite AR-C124910XX. The causal associations of ticagrelor and its major active metabolite AR-C124910XX with drug indications （coronary artery disease， unstable angina pectoris， myocardial infarction， stroke and ischemic stroke）were analyzed by inverse variance weighted Mendelian randomization model as a positive control for genetic instrumental variables. The causal relationship between ticagrelor and bacterial infection， acute lower respiratory infection， bacterial pneumoniae， pneumoniae，acute upper respiratory infection and sepsis were furtheranalyzed by using this method， and the robustness of the results was assessed by using heterogeneity tests and horizontal 202002030415） pleiotropy tests. RESULTS The increase of area under the curve at steady state （AUCss） of the genetic surrogated ticagrelor significantly reduced the risk of coronary artery disease， myocardial infarction and unstable angina pectoris （P＜0.001）. AUCss genetic instrument variables of its main active metabolite AR-C124910XX failed to pass positive control. Further analysis showed that the increase of the genetic surrogated ticagrelor exposure suggestively reduced the risk of bacterial infection [OR（95%CI）＝0.80（0.65，0.99），P＝0.040] and sepsis [OR （95%CI）＝0.84（0.73， 0.98）， P＝0.023]. The results of the heterogeneity tests showed that there was no heterogeneity in the causal association of the genetic surrogated ticagrelor AUCss with bacterial infection and sepsis （P＞0.05）. The results of horizontal pleiotropy tests showed that the causal association of genetic surrogated ticagrelor AUCss with bacterial infection and sepsis had no effects on horizontal pleiotropy （P＞0.05）. CONCLUSIONS Ticagrelor has a potential role in reducing the risk of sepsis and bacterial infections.

Association of C-reactive Protein with Cardiovascular Outcomes: A Mendelian Randomization Study in the Japanese Population / 生物医学与环境科学（英文）

OBJECTIVE@#Traditional epidemiological studies have shown that C-reactive protein (CRP) is associated with the risk of cardiovascular diseases (CVDs). However, whether this association is causal remains unclear. Therefore, Mendelian randomization (MR) was used to explore the causal relationship of CRP with cardiovascular outcomes including ischemic stroke, atrial fibrillation, arrhythmia and congestive heart failure.@*METHODS@#We performed two-sample MR by using summary-level data obtained from Japanese Encyclopedia of Genetic association by Riken (JENGER), and we selected four single-nucleotide polymorphisms associated with CRP level as instrumental variables. MR estimates were calculated with the inverse-variance weighted (IVW), penalized weighted median and weighted median. MR-Egger regression was used to explore pleiotropy.@*RESULTS@#No significant causal association of genetically determined CRP level with ischemic stroke, atrial fibrillation or arrhythmia was found with all four MR methods (all Ps > 0.05). The IVW method indicated suggestive evidence of a causal association between CRP and congestive heart failure ( OR: 1.337, 95% CI: 1.005-1.780, P = 0.046), whereas the other three methods did not. No clear pleiotropy or heterogeneity were observed.@*CONCLUSIONS@#Suggestive evidence was found only in analysis of congestive heart failure; therefore, further studies are necessary. Furthermore, no causal association was found between CRP and the other three cardiovascular outcomes.

Métodos para avaliação da efetividade de vacinas para COVID-19 com ênfase em abordagens quase-experimentais / Methods to evaluate COVID-19 vaccine effectiveness, with an emphasis on quasi-experimental approaches

Resumo A avalição da efetividade de vacinas é feita com dados do mundo real e é essencial para monitorar o desempenho dos programas de vacinação ao longo do tempo bem como frente a novas variantes. Até o momento, a avaliação da efetividade das vacinas para COVID-19 tem sido baseada em métodos clássicos como estudos de coorte e caso controle teste-negativo, que muitas vezes podem não permitir o adequado controle dos vieses intrínsecos da alocação das campanhas de vacinação. O objetivo dessa revisão foi discutir os desenhos de estudo disponíveis para avaliação de efetividade das vacinas, enfatizando os estudos quase-experimentais, que buscam mimetizar os estudos aleatorizados ao introduzir um componente exógeno para atribuição ao tratamento, bem como suas vantagens, limitações e aplicabilidade no contexto dos dados brasileiros. O emprego de métodos quase-experimentais, incluindo as séries temporais interrompidas, o método de diferença em diferenças, escore de propensão, variáveis instrumentais e regressão descontínua, são relevantes pela possibilidade de gerar estimativas mais acuradas da efetividade de vacinas para COVID-19 em cenários como o brasileiro, que se caracteriza pelo uso de várias vacinas, com respectivos número e intervalos entre doses, aplicadas em diferentes faixas etárias e em diferentes momentos da pandemia.

Abstract The evaluation of vaccine effectiveness is conducted with real-world data. They are essential to monitor the performance of vaccination programmes over time, and in the context of the emergence of new variants. Until now, the effectiveness of COVID-19 vaccines has been assessed based on classic methods, such as cohort and test-negative case-control studies, which may often not allow for adequate control of inherent biases in the assignment of vaccination campaigns. The aim of this review was to discuss the study designs available to evaluate vaccine effectiveness, highlighting quasi-experimental studies, which seek to mimic randomized trials, by introducing an exogenous component to allocate to treatment, in addition to the advantages, limitations, and applicability in the context of Brazilian data. The use of quasi-experimental approaches, such as interrupted time series, difference-in-differences, propensity scores, instrumental variables, and regression discontinuity design, are relevant due to the possibility of providing more accurate estimates of COVID-19 vaccine effectiveness. This is especially important in scenarios such as the Brazilian, which characterized by the use of various vaccines, with the respective numbers and intervals between doses, applied to different age groups, and introduced at different times during the pandemic.

Como o desmatamento influencia a ocorrência de leishmaniose visceral? Uma abordagem contrafactual / How deforestation influence tha occurrence of Visceral Leishmaniasis? A counterfactual approach

A leishmaniose visceral (LV) é uma doença sistêmica de transmissão vetorial. No Brasil, ela é causada pelo protozoário Leishmania infantum e é transmitida por flebotomíneos do gênero Lutzomyia, tendo os cães como a principal fonte de infecção em áreas urbanas. Historicamente a LV era conhecida como uma doença endêmica rural, porém desde a década de 1980, ela atingiu proporções endêmicas e epidêmicas em grandes cidades brasileiras. Desde então vários fatores são considerados como norteadores da expansão da LV, como variáveis socioeconômicas, climáticas e ambientais. Mais especificamente sobre o efeito do desmatamento e perturbações antrópicas no ambiente, a maioria do que se encontra na literatura tem natureza qualitativa ou utiliza de abordagens reducionistas, sem considerar a complexidade da dinâmica de uma doença infecciosa de transmissão vetorial e de caráter zoonóticos. Na presente dissertação, investigamos o efeito do desmatamento na ocorrência de Lutzomyia longipalpis (Lu. longipalpis), leishmaniose visceral canina (LVC) e leishmaniose visceral humana (LVH), tomando como exemplo o estado de São Paulo. Para isso, utilizamos uma abordagem contrafactual para estimar os efeitos (geral, direto e indireto) do desmatamento na ocorrência do Lu. longipalpis/LVC/LVH. Isso foi feito em dois passos, primeiro estimamos os parâmetros por meio de um algoritmo de Metropolis-Hastings duplo e, por fim, estimamos os efeitos causais através de um amostrador de Gibbs, por meio do pacote autognet no R.Vimos que municípios desmatados apresentam 2.63, 2.07 e 3.18 maiores chances de apresentar o vetor, LVC e LVH, respectivamente quando comparados com os municípios que não apresentaram desmatamento. Foi observada também uma forte influência da presença do vetor, LVC e LVH dos municípios vizinhos na ocorrência dos mesmos em municípios previamente livres dos desfechos (6.67, 4.26 e 4.27). Já sob mudanças hipotéticas de prevalência do desmatamento de 50% para 0% no estado, são esperadas quedas na prevalência do vetor, LVC e LVH de 11%, 6.67% e 29.87% respectivamente. O desmatamento influi na ocorrência do vetor, doença em cães e humanos por duas principais vias, (i) alterando o funcionamento do ecossistema e estrutura da comunidade, permitindo a reprodução e colonização do vetor; e (ii) promovendo uma aproximação entre todos os componentes do ciclo da LV. De tal modo, para correto controle da LV e doenças infecciosas como um todo, é imprescindível um desenvolvimento ecologicamente correto com soluções viáveis para as compensações entre a agricultura, urbanização e conservação. urbanização e conservação.

Visceral leishmaniasis (VL) is a systemic vector-borne disease. In Brazil, it caused by the protozoan Leishmania infantum and is transmitted by sandflies of the genus Lutzomyia, with dogs as the principal source of infection in urban areas. Historically, VL was known as a rural endemic disease, since the 80's it has become endemic and epidemic in large Brazilian cities. Since then, many factors were hypothesised as driving VL expansion, as socioeconomic, climatic and environmental variables. More specifically, concerning deforestation and human-made actions in the environment, most studies tend to be qualitative in nature or use traditional reductionist approaches, ignoring the complexities that are inherent of vector-borne zoonotic infectious diseases. The present study aimed to investigate the effect of deforestation in the occurrence of Lutzomyia longipalpis, canine visceral leishmaniasis (CVL), and human visceral leishmaniasis (HVL), taking as a motivating example the São Paulo state (Brazil). To this end, we chose a counterfactual approach to estimate the effects (overall, direct and indirect) of deforestation in the occurrence of vector/CVL/HVL. We did it in two steps; first, we estimated the parameters through a double Metropolis-Hastings algorithm and, finally, we estimated the causal effects through a Gibbs sampler, using the autognet package in R. We observe that deforested cities show 2.63, 2.07, and 3.18 higher odds of vector/CVL/HVL occurrence, respectively, when compared to non-deforested municipalities. We also see a significant influence of vector, CVL, and HVL presence in the neighbours in its appearance in previous naive cities, 6.67, 4.26, 4,27 respectively. Lastly, under hypothetical changes in deforestation's prevalence from 50% to 0% in the whole state, is expected a decrease in its prevalence of the vector, LVC and LVH of 11%, 6.67% and 29.87% respectively. Deforestation in the occurrence of infectious diseases and, more specifically, VL importance, is two-folded: (i) changing's the ecosystem equilibrium and community structure, allowing its vector to reproduce and colonise; (ii) promoting a close contact through the VL cycle components. In such a way, for correct control of VL and infectious disease as a whole, it is essential an eco-friendly development with viable solutions for trade-offs between agriculture, urbanization and conservation.

Exploring the causal relationship between hip circumference and type 2 diabetes based on mendelian randomization / 中华疾病控制杂志

Objective To investigate the causal association between hip circumference (HC) and type 2 diabetes mellitus (T2DM) based on Mendelian randomization. Methods The genetic variants data of the HC and T2DM from the Genetic Investigation of Anthropometric Traits (GIANT) and DIAbetes Genetics Replication And Meta-analysis (DIAGRAM) database were matched according to the single nucleotide polymorphism (SNP) rsID. Genetic loci strongly related to the HC were used as instrumental variables; and the inverse-variance weighting, MR-Egger regression model and weighting median method were carried out to analyze the causal effect of HC on T2DM. Results Fifty-two, nine and fifteen SNPs were matched in the total cohort, female cohort and male cohort, respectively. Heterogeneity test suggested the SNPs were homogeneous. We found HC to be positively associated with T2DM risk (OR=1.065, 95% CI: 1.030-1.100, OR=1.103, 95% CI: 1.057-1.150 and OR=1.583, 95% CI: 1.273-1.968, respectively) in above three cohorts, respectively. Sensitivity analysis showed the results were robust. Conclusions There is a relationship between HC and T2DM of people, and HC may be the risk factor of T2DM.

Sensitivity analysis method for unmeasured confounding interference in observational study / 中华流行病学杂志

Objective@#To introduce the methods for sensitivity analysis, discuss and compare the advantages and disadvantages of different methods.@*Methods@#The difference between confounding function method and bounding factor method in accuracy of identifying unmeasured confounding factors in observational studies through simulation trials and actual clinical data was compared.@*Results@#The results of simulation trials and actual clinical data showed that when there was unmeasured confounding between exposure (X) and outcome (Y), the results of confounding function and the bounding factor analysis were similar in terms of the effect of unmeasured confounding factor to lead to the complete change of the magnitude and direction of the observed effect value. However, the confounding function method needed smaller confounding effect to fully interpret the observed effect value than the bounding factor needed. In addition, the bounding factor method needed to analyze two confounding parameters, while only one parameter was needed in the confounding function method. The confounding function method was simpler and more sensitive than the bounding factor method.@*Conclusion@#For real-world observational data, the sensitivity analysis process is essential in analyzing the causal effects between exposure (X) and outcome (Y). In terms of the calculation process and result interpretation the sensitivity analysis method of confounding function is worth to recommend.

A new mediation analysis method for multiple mediators / 中华流行病学杂志

Mediation analysis is mainly used to explore the causal mechanism between independent variable X and dependent variable Y. It determines whether mediator M plays a role and evaluate the role’s degree in the causal path by decomposing the causal path between the independent variable X and the dependent variable Y. However, the classical mediation analysis is generally used for single mediator. This paper introduces a new mediation analysis method for multiple mediators.

The application of causal thinking in several issues in estimation of effects / 中华流行病学杂志

Epidemiology is a branch of science that mainly involves in the etiology studies of non-randomness phenomenon among homogenous populations. In this paper, we use causal-thinking, supported by its tool-Directed Acyclic Graphs, to illustrate how the estimation of effects is affected by the issues as relations between effect and association, time sequences between variables and their measured counterparts, natural picture of dynamic population, formation of susceptible population, selection of study population, impact of covariates and types of cases etc., on the estimation of effects. This type of thinking may help us to re-capture the epidemiological theories, methods and related applications. Thus, causal-thinking should be strengthened.

Application of mendelian randomization methods in causal inference of observational study / 中华预防医学杂志

Mendelian randomization (MR) approach follows the Mendel′s law of inheritance, which is called "Parental alleles randomly assigned to the offspring", and refers to use genetic variants as an instrumental variable to develop causal inference between the exposure factor and the outcome from observational study. In recent years, with the rapid development of genome-wide association study (GWAS) and various omics data,the disclosure of a large number of aggregated data provides an opportunity for the wide application of MR approach in causal inference. We introduce three methods widely used in MR and then apply them to explore causal relationship between blood metabolites and depressive. The advantages and disadvantages of three methods in causal inference are compared in order to provide reference for the application of MR in observational studies.

Pre-hypertension and the risk of diabetes mellitus incidence using a marginal structural model in an Iranian prospective cohort study / 한국역학회지

OBJECTIVES: The aim of this study was to evaluate the effect of pre-hypertension and its sub-classification on the development of diabetes. METHODS: In this cohort study, 2,941 people 40 to 64 years old without hypertension or diabetes were followed from 2009 through 2014. According to the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC)-7 criteria, we classified participants into normal and pre-hypertension groups. The effect of pre-hypertension on the 5-year incidence rate of diabetes was studied using inverse probability of treatment weighting. We modeled the exposure and censored cases given confounding factors such as age, sex, body mass index, smoking, economic status, and education. RESULTS: The 5-year incidence rate of diabetes among people with pre-hypertension and those with normal blood pressure (BP) was 12.7 and 9.7%, respectively. The risk ratio (RR) for people with pre-hypertension was estimated to be 1.13 (95% confidence interval [CI], 0.90 to 1.41). The RRs among people with normal BP and high-normal BP, according to the JNC-6 criteria, compared to those with optimal BP were 0.96 (95% CI, 0.73 to 1.25) and 1.31 (95% CI, 1.01 to 1.72), respectively. CONCLUSIONS: Our results showed that participants who had higher levels of BP (high-normal compared to optimal BP) had a higher risk of diabetes development. With regard to the quantitative nature of BP, using the specifically distinguishing of stage 1 hypertension or high-normal BP may be a more meaningful categorization for diabetes risk assessment than the JNC-7 classification.

Pre-hypertension and the risk of diabetes mellitus incidence using a marginal structural model in an Iranian prospective cohort study / 한국역학회지

OBJECTIVES: The aim of this study was to evaluate the effect of pre-hypertension and its sub-classification on the development of diabetes.METHODS: In this cohort study, 2,941 people 40 to 64 years old without hypertension or diabetes were followed from 2009 through 2014. According to the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC)-7 criteria, we classified participants into normal and pre-hypertension groups. The effect of pre-hypertension on the 5-year incidence rate of diabetes was studied using inverse probability of treatment weighting. We modeled the exposure and censored cases given confounding factors such as age, sex, body mass index, smoking, economic status, and education.RESULTS: The 5-year incidence rate of diabetes among people with pre-hypertension and those with normal blood pressure (BP) was 12.7 and 9.7%, respectively. The risk ratio (RR) for people with pre-hypertension was estimated to be 1.13 (95% confidence interval [CI], 0.90 to 1.41). The RRs among people with normal BP and high-normal BP, according to the JNC-6 criteria, compared to those with optimal BP were 0.96 (95% CI, 0.73 to 1.25) and 1.31 (95% CI, 1.01 to 1.72), respectively.CONCLUSIONS: Our results showed that participants who had higher levels of BP (high-normal compared to optimal BP) had a higher risk of diabetes development. With regard to the quantitative nature of BP, using the specifically distinguishing of stage 1 hypertension or high-normal BP may be a more meaningful categorization for diabetes risk assessment than the JNC-7 classification.

Applied mediation analyses: a review and tutorial / 한국역학회지

In recent years, mediation analysis has emerged as a powerful tool to disentangle causal pathways from an exposure/treatment to clinically relevant outcomes. Mediation analysis has been applied in scientific fields as diverse as labour market relations and randomized clinical trials of heart disease treatments. In parallel to these applications, the underlying mathematical theory and computer tools have been refined. This combined review and tutorial will introduce the reader to modern mediation analysis including: the mathematical framework; required assumptions; and software implementation in the R package medflex. All results are illustrated using a recent study on the causal pathways stemming from the early invasive treatment of acute coronary syndrome, for which the rich Danish population registers allow us to follow patients' medication use and more after being discharged from hospital.

Applied mediation analyses: a review and tutorial / 한국역학회지

In recent years, mediation analysis has emerged as a powerful tool to disentangle causal pathways from an exposure/treatment to clinically relevant outcomes. Mediation analysis has been applied in scientific fields as diverse as labour market relations and randomized clinical trials of heart disease treatments. In parallel to these applications, the underlying mathematical theory and computer tools have been refined. This combined review and tutorial will introduce the reader to modern mediation analysis including: the mathematical framework; required assumptions; and software implementation in the R package medflex. All results are illustrated using a recent study on the causal pathways stemming from the early invasive treatment of acute coronary syndrome, for which the rich Danish population registers allow us to follow patients' medication use and more after being discharged from hospital.

GBM Propensity Score Weighting for Causal Inference Research / 世界科学技术-中医药现代化

Objective In observational studies or non-randomized design,the researchers' ability to make causal inferences from data was hampered by confounding factors.This study used this method to analyze a group of observational medical data in order to instruct relevant medical personnel to carry out their own causal inference studies.Methods At present,the four main types of propensity scoring methods:matching,stratification,inverse probability weighting and covariate adjustment have been widely used in the study of causal inference.Propensity score method can theoretically eliminate the bias of the observable confounding factors,so that the treatments variables are close to the result of random assignment design,thus,it is estimated that the treatment factor has a causal effect on the outcome.Results Considering the advantages of the inverse probability weighting method over other methods,this paper summarizes the applicable conditions for the estimate of causal effect,particularly illustrates the use of a modern nonparametric statistical technology--Generalized Boosted Models (GBM) and its advantages and disadvantages.Conclusion When there is a lot of different types of confounding factors,and uncertain functional forms for their associations with treatment selection in linear,non-linear or interaction effect,and other issues,GBM propensity score weighting method can overcome the obstacles in the process of accurately estimating propensity score.

Pobreza y remesas internacionales Sur-Sur en Paraguay / Pobreza e remessas internacionais Sul-Sul no Paraguai / Poverty and south-south financial remittances in Paraguay

La discusión sobre migración y desarrollo está fuertemente vinculada al papel de las remesas internacionales. Sin embargo, no existe consenso sobre los efectos que ellas provocan en las economías de origen y los hogares receptores. El objetivo de este artículo es analizar el efecto de la recepción de remesas regionales en el nivel y la incidencia de la pobreza de los hogares paraguayos. Para ello se utilizan microdatos de la Encuesta Permanente de Hogares de Paraguay de 2009, de la Dirección General de Estadística, Encuestas y Censos (DGEEC). Se consideran remesas regionales las provenientes de Argentina y Brasil. Se utiliza el método de análisis de la puntuación de la propensión (propensity score analysis) para construir grupos comparables y aislar el efecto de la recepción de remesas de otras variables que inciden sobre la condición de pobreza de los hogares. Se sugiere que las remesas tendrían un efecto positivo en la incidencia de la pobreza y el alivio de la pobreza extrema. Sin embargo, el resultado no es completamente concluyente, ya que la pobreza no extrema afecta en mayor medida a los hogares receptores de remesas.

A discussão entre migração e desenvolvimento está fortemente vinculada ao papel das remessas internacionais. Contudo, não existe consenso sobre os efeitos que tais remessas provocam nas economias de origem e nos domicílios receptores. Este artigo analisa o efeito da recepção de remessas regionais no nível e incidência da pobreza em domicílios paraguaios. Para tanto, utilizam-se microdados da Pesquisa Permanente Domiciliar do Paraguai de 2009, da Dirección General de Estadística, Encuestas y Censos (DGEEC, Paraguai). Consideram-se remessas regionais aquelas provenientes da Argentina e do Brasil. Utiliza-se o método de análise da pontuação da propensão (propensity score analysis) para construir grupos comparáveis e, desta forma, isolar o efeito da recepção de remessas de outras variáveis que incidem sobre a condição de pobreza dos domicílios. Os resultados sugerem que as remessas teriam um efeito positivo em aliviar a pobreza extrema e a incidência da pobreza. No entanto, o resultado não é completamente conclusivo, pois a pobreza não extrema afeta em maior medida os domicílios receptores de remessas.

There is a debate going on about international financial remittances in terms of the connections between migration and development. However, there is no consensus as to the effects that these remittances have on economies of origin and on receiving households. In this paper we analyze the effect of the receiving of regional remittances on the level and incidence of poverty among Paraguayan households. We use micro data from the 2009 Permanent Household Survey, conducted by the General Department of Statistics, Surveys and Censuses (DGEEC, Paraguay). Regional remittances are defined as those sent from Argentina and Brazil. We applied the method of propensity score analysis to construct comparable groups and thus isolate the effect of reception of regional remittances from other variables that affect the poverty status of households. Results suggest that remittances do have a positive effect in alleviating extreme poverty and the incidence of poverty. However, the result is not entirely conclusive, since non-extreme poverty more strongly affects the households that receive remittances.

Causal inference at the population level.

Three elements are needed to formalize a causal quantity at the population level: response, treatment, and the causal element, which are introduced here by notation. Inclusion of two essential causal assumptions, the monitoring and illumination assumptions, in a function distinguishes causal from association analyses. The discussion provides insight into causal inference.