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Causal inference

Yong-Muh Ng, Soo-Kun Lim, Pei-San Kang, Khairul Azmi Abdul Kadir, Mei-Ling Sharon Tai
BACKGROUND: Epidemiological studies have shown an inverse relationship between vitamin D levels and cardiovascular diseases. However, this does not infer a causal relationship between the two. Chronic kidney disease (CKD) patients have a high prevalence of vitamin D deficiency and carotid atherosclerosis. Therefore, in this study we have aimed to determine the association between serum 25-hydroxyvitamin D levels and carotid atherosclerosis in the CKD population. METHODS: 100 CKD stage 3-4 patients were included in the study...
October 18, 2016: BMC Nephrology
A Kibleur, G Gras-Combe, D Benis, J Bastin, T Bougerol, S Chabardès, M Polosan, O David
High-frequency deep brain stimulation of the subthalamic nucleus can be used to treat severe obsessive-compulsive disorders that are refractory to conventional treatments. The mechanisms of action of this approach possibly rely on the modulation of associative-limbic subcortical-cortical loops, but remain to be fully elucidated. Here in 12 patients, we report the effects of high-frequency stimulation of the subthalamic nucleus on behavior, and on electroencephalographic responses and inferred effective connectivity during motor inhibition processes involved in the stop signal task...
October 18, 2016: Translational Psychiatry
Angie M Johnston, Samuel G B Johnson, Marissa L Koven, Frank C Keil
Like scientists, children seek ways to explain causal systems in the world. But are children scientists in the strict Bayesian tradition of maximizing posterior probability? Or do they attend to other explanatory considerations, as laypeople and scientists - such as Einstein - do? Four experiments support the latter possibility. In particular, we demonstrate in four experiments that 4- to 8-year-old children, like adults, have a robust latent scope bias that leads to inferences that do not maximize posterior probability...
October 17, 2016: Developmental Science
Stephen Burgess, Jack Bowden, Tove Fall, Erik Ingelsson, Simon G Thompson
Mendelian randomization investigations are becoming more powerful and simpler to perform, due to the increasing size and coverage of genome-wide association studies and the increasing availability of summarized data on genetic associations with risk factors and disease outcomes. However, when using multiple genetic variants from different gene regions in a Mendelian randomization analysis, it is highly implausible that all the genetic variants satisfy the instrumental variable assumptions. This means that a simple instrumental variable analysis alone should not be relied on to give a causal conclusion...
September 26, 2016: Epidemiology
Mohammad Ali Mansournia, Julian P T Higgins, Jonathan A C Sterne, Miguel A Hernán
Trialists and epidemiologists often employ different terminology to refer to biases in randomized trials and observational studies, even though many biases have a similar structure in both types of study. We use causal diagrams to represent the structure of biases, as described by the Cochrane Collaboration for randomized trials, and provide a translation to the usual epidemiologic terms of confounding, selection bias, and measurement bias. This structural approach clarifies that an explicit description of the inferential goal-the intention-to-treat effect or the per-protocol effect-is necessary to assess risk of bias in the estimates...
September 28, 2016: Epidemiology
Laurens Holmes, Joshua Tworig, Joseph Casini, Isabel Morgan, Kathleen O'Brien, Patricia Oceanic, Kirk Dabney
BACKGROUND: Sports-related concussion remains a public health challenge due to its morbidity and mortality. One of the consequences of concussion is cognitive impairment (CI) and cognitive-related symptoms (CRS) which determine, to some extent, physical and behavioral functioning of children who sustain concussion. Despite the high prevalence of CI and CRS associated with concussion, the risk factors are not fully understood. We aimed to characterize CRS and to examine its relationship with race, ethnicity, age, insurance, and sex in a pediatric population...
December 2016: Sports Medicine—Open
Kevin Trentino, Shannon Farmer, Irwin Gross, Aryeh Shander, James Isbister
BACKGROUND: As defined by evidence-based medicine randomized controlled trials rank higher than observational studies in the hierarchy of clinical research. Accordingly, when assessing the effects of treatments on patient outcomes, there is a tendency to focus on the study method rather than also appraising the key elements of study design. A long-standing debate regarding findings of randomized controlled trials compared with those of observational studies, their strengths and limitations and questions regarding causal inference, has recently come into focus in relation to research assessing patient outcomes in transfusion medicine...
October 14, 2016: BMC Anesthesiology
Matthew S Fritz, David A Kenny, David P MacKinnon
Mediation analysis requires a number of strong assumptions be met in order to make valid causal inferences. Failing to account for violations of these assumptions, such as not modeling measurement error or omitting a common cause of the effects in the model, can bias the parameter estimates of the mediated effect. When the independent variable is perfectly reliable, for example when participants are randomly assigned to levels of treatment, measurement error in the mediator tends to underestimate the mediated effect, while the omission of a confounding variable of the mediator-to-outcome relation tends to overestimate the mediated effect...
September 2016: Multivariate Behavioral Research
Bethany Lusch, Pedro D Maia, J Nathan Kutz
Determining the interactions and causal relationships between nodes in an unknown networked dynamical system from measurement data alone is a challenging, contemporary task across the physical, biological, and engineering sciences. Statistical methods, such as the increasingly popular Granger causality, are being broadly applied for data-driven discovery of connectivity in fields from economics to neuroscience. A common version of the algorithm is called pairwise-conditional Granger causality, which we systematically test on data generated from a nonlinear model with known causal network structure...
September 2016: Physical Review. E
R Whittle, G Mansell, P Jellema, D van der Windt
BACKGROUND: Many randomized controlled trials (RCTs) of psychosocial interventions for low back pain (LBP) have been found to have only small effects on disability outcomes. Investigations of the specific mechanisms that may lead to an improvement in outcome have therefore been called for. METHODS: We present an application of the causal inference approach to mediation analysis using the example of a cluster RCT in a primary care population with (sub)acute LBP randomized to either usual GP care (n = 171) or a minimal psychosocial intervention (n = 143)...
October 14, 2016: European Journal of Pain: EJP
Dea Seidenfaden, Ulla Knorr, Mia Greisen Soendergaard, Henrik Enghusen Poulsen, Anders Fink-Jensen, Martin Balslev Jorgensen, Anders Jorgensen
BACKGROUND: Childhood adversity is a well-established risk factor for the development of schizophrenia. In particular, there is evidence that childhood adversity increases the occurrence of positive symptoms, possibly through glucocorticoid influences on dopaminergic neurotransmission. AIMS: To compare levels of childhood trauma in schizophrenia patients vs. healthy control persons, and to study the association between childhood adversity and the symptomatology of adulthood schizophrenia, as well as subjective and biological markers of psychological stress...
September 24, 2016: Comprehensive Psychiatry
Andrew P Jaciw
BACKGROUND: Past studies have examined factors associated with reductions in bias in comparison group studies (CGSs). The companion work to this article extends the framework to investigate the accuracy of generalized inferences from CGS. OBJECTIVES: This article empirically examines levels of bias in CGS-based impact estimates when used for generalization, and reductions in bias resulting from covariate adjustment. It assesses potential for bias reduction against criteria from past studies...
October 12, 2016: Evaluation Review
F Lotti, G Corona, G Castellini, E Maseroli, M G Fino, M Cozzolino, M Maggi
STUDY QUESTION: Is sexual dysfunction associated with severity of semen quality impairment in men with couple infertility? SUMMARY ANSWER: In males of infertile couples the prevalence of erectile dysfunction (ED) increases as a function of semen quality impairment severity. WHAT IS KNOWN ALREADY: Infertile men are at a higher risk for sexual dysfunction, psychopathological and general health disorders. However, it has never been systematically investigated if these problems are associated with severity of semen quality impairment...
October 12, 2016: Human Reproduction
Mina Ha, Soon Young Lee, Seung-Sik Hwang, Hyesook Park, Seungsoo Sheen, Hae Kwan Cheong, Bo Youl Choi
OBJECTIVES: As of November 2011, the Korean government recalled and banned humidifier disinfectants (HDs) from the market, because four case-control studies and one retrospective epidemiological study proved the association between HDs and lung injury of unknown cause. The report reviewed the causal role of HDs in lung injury based on scientific evidences. METHODS: A careful examination on the association between the HDs and lung injury was based on the criteria of causality inference by Hill and the US Surgeon General Expert Committee...
2016: Epidemiology and Health
Paméla Filiatrault-Veilleux, Caroline Bouchard, Natacha Trudeau, Chantal Desmarais
Purpose: This study aimed to describe the development of inferential abilities of children age 3 to 6 years in a narrative using a dialogic reading task on an iPad. Method: Participants were 121 typically developing children, divided into 3 groups according to age range (3-4 years old, 4-5 years old, 5-6 years old). Total score of inferential comprehension, subscores by causal inference type targeting elements of the story grammar, and quality of response were examined across groups...
October 12, 2016: Journal of Speech, Language, and Hearing Research: JSLHR
Daniel Backenroth, Herbert Chase, Carol Friedman, Ying Wei
Recent research has suggested that the case-control study design, unlike the self-controlled study design, performs poorly in controlling confounding in the detection of adverse drug reactions (ADRs) from administrative claims and electronic health record (EHR) data, resulting in biased estimates of the causal effects of drugs on health outcomes of interest (HOI) and inaccurate confidence intervals. Here we show that using rich data on comorbidities and automatic variable selection strategies for selecting confounders can better control confounding within a case-control study design and provide a more solid basis for inference regarding the causal effects of drugs on HOIs...
2016: PloS One
Tom Loeys, Wouter Talloen, Liesbet Goubert, Beatrijs Moerkerke, Stijn Vansteelandt
It is well known from the mediation analysis literature that the identification of direct and indirect effects relies on strong no unmeasured confounding assumptions of no unmeasured confounding. Even in randomized studies the mediator may still be correlated with unobserved prognostic variables that affect the outcome, in which case the mediator's role in the causal process may not be inferred without bias. In the behavioural and social science literature very little attention has been given so far to the causal assumptions required for moderated mediation analysis...
November 2016: British Journal of Mathematical and Statistical Psychology
Keisuke Ejima, Peng Li, Daniel L Smith, Tim R Nagy, Inga Kadish, Thomas van Groen, John A Dawson, Yongbin Yang, Amit Patki, David B Allison
BACKGROUND: Differing opinions exist on whether associations obtained in observational studies can be reliable indicators of a causal effect if the observational study is sufficiently well controlled and executed. MATERIALS AND METHODS: To test this, we conducted two animal observational studies that were rigorously controlled and executed beyond what is achieved in studies of humans. In study 1, we randomized 332 genetically identical C57BL/6J mice into three diet groups with differing food energy allotments and recorded individual self-selected daily energy intake and lifespan...
October 6, 2016: European Journal of Clinical Investigation
Brian Hallstrom, Bonita Singal, Mark E Cowen, Karl C Roberts, Richard E Hughes
BACKGROUND: The efficacy of tranexamic acid (TXA) in reducing blood loss and transfusion requirements in total hip and knee arthroplasty has been well established in small controlled clinical trials and meta-analyses. The purpose of the current study was to determine the risks and benefits of TXA use in routine orthopaedic surgical practice on the basis of data from a large, statewide arthroplasty registry. METHODS: From April 18, 2013, to September 30, 2014, there were 23,236 primary total knee arthroplasty cases and 11,489 primary total hip arthroplasty cases completed and registered in the Michigan Arthroplasty Registry Collaborative Quality Initiative (MARCQI)...
October 5, 2016: Journal of Bone and Joint Surgery. American Volume
Kalyan C Mantripragada, Fatima Hamid, Hammad Shafqat, Adam J Olszewski
BACKGROUND: Management of resected gallbladder cancer relies on single-arm trials and retrospective observations. Our objective was to evaluate adjuvant therapy in a nationwide data set using causal inference methods to address sources of bias. METHODS: We studied patients with T2-3 or node-positive, nonmetastatic gallbladder cancer, resected with grossly negative margins and reported to the National Cancer Data Base between 2004 and 2011. We defined adjuvant therapy as any chemotherapy within 90 days of surgery, and upfront concurrent chemoradiation as radiation within 14 days of first chemotherapy...
February 2017: Journal of the National Cancer Institute
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