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Results for “causality”

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PubMedDate not supplied

Development of a structural equation model for causal relationships among arteriosclerosis risk factors.

The purpose of this study was to clarify the dynamic causal relationships among arteriosclerotic risk factors, including age, smoking, alcoholic consumption, exercise, hypercholesterolemia, hypertriglyceridemia, and hypertension. Data were collected from the medical records of 400 male clients who visited a university hospital located in Inchon, Korea, from May 1996 to December 1996 for physical examinations. The Lineal Structural Relationships 8 program was used to verify the fitness of the hypothetical model to data. All of the fit statistics, except the Chi-square value, showed that the hypothetical model was well fitted to the data. Seven percent of obesity was explained by the variables of age, smoking, alcohol consumption, and exercise. Sixty percent of hyperlipidemia could be explained by the variables of age, smoking, exercise, and obesity. And 22% of hypertension was explained by the variables of age, smoking, alcohol consumption, exercise, and hyperlipidemia. Our results showed that these risk factors were directly and indirectly interrelated, and lifestyle variables (smoking, alcohol consumption, and exercise) influence almost all of arteriosclerotic risk factors.

Arteriosclerosis↗

PubMed2003

[Acute appendicitis after colonoscopy: causality or coincidence?].

Complications due to diagnostic colonoscopy are very rare. Perforation is the most frequent colon-related event. So far only ten cases of acute appendicitis after colonoscopy have been reported in the literature. We present the case of a 79-year-old man who developed acute appendicitis after diagnostic colonoscopy. Diagnosis was aggravated by the fact that in the patient's history an appendectomy had been performed 65 years earlier. Because of the rarity of this event it is doubtful whether the endoscopic examination was causal or coincidental. However, in cases of pain after colonoscopy, appendicitis has to be included in the differential diagnosis.

Abdomen, Acute↗

PubMed2006

Stochastic modeling of neurobiological time series: power, coherence, Granger causality, and separation of evoked responses from ongoing activity.

In this article we consider the stochastic modeling of neurobiological time series from cognitive experiments. Our starting point is the variable-signal-plus-ongoing-activity model. From this model a differentially variable component analysis strategy is developed from a Bayesian perspective to estimate event-related signals on a single trial basis. After subtracting out the event-related signal from recorded single trial time series, the residual ongoing activity is treated as a piecewise stationary stochastic process and analyzed by an adaptive multivariate autoregressive modeling strategy which yields power, coherence, and Granger causality spectra. Results from applying these methods to local field potential recordings from monkeys performing cognitive tasks are presented.

Action Potentials↗

PubMed1999

Inferring causality from relational data and designs: historical and contemporary lessons for research and clinical practice.

My address to you today is born of frustration with the growing claims, evident in the research literature and in clinical reports that happen to cross my desk, of causation made on the basis of correlational data. I recall, as a sophomore in college, being taught early in my first experimental psychology course, "you cannot infer causality from correlation." This point was made adamant in my first face-to-face critique of an experimental psychology research paper by Dr. Robert T. Brown, who pointed out, in lowering my grade, that I had inferred organic causes to behavior patterns in gerbils based solely on correlational data. This caution was reiterated in my statistics courses until it must have been indelibly stamped upon my then still somewhat plastic brain.

Analysis of Variance↗

PubMedDate not supplied

Moderating and mediating effects in causal models.

This article explains causal relationships in conceptual models of mental health phenomena. Direct, moderating, mediating, and reciprocal effects among variables are defined, appropriate statistical analyses are described, and the correct interpretations of moderating versus mediating effects are discussed. Examples are provided that will help the reader to distinguish between moderating and mediating effects.

Adaptation, Psychological↗

PubMed2025

Exploring the causal role of plasma metabolites in pediatric asthma: a Mendelian randomization study.

BACKGROUND: Pediatric asthma (PA) is the prevailing chronic respiratory ailment in childhood. A better understanding of plasma metabolites is the goal for elucidating the molecular pathological mechanisms of PA and investigating novel therapeutic approaches. METHODS: Data for PA from Genome-Wide Association Studies (GWAS) was derived from the IEU-OpenGWAS project, featuring a collection of 1400 plasma metabolites. The inverse-variance weighting (IVW) method assessed causal relationships between plasma metabolites and PA, with measures taken to mitigate horizontal pleiotropy and heterogeneity. To select instrumental variables, a genome-wide significance threshold (p < 5 × 10-8) was applied to ensure robust genetic instruments. A Bonferroni correction controlled for multiple testing, with statistical significance defined as p < 3.57 × 10-5) (0.05/1400). To further substantiate outcomes, a reverse Mendelian randomization analysis was conducted. RESULTS: Research found 91 plasma metabolites linked to PA, ten of which showed significant associations. Of note, 20:4n6 levels (IVW: OR (95% CI) = 1.062 (1.030 to 1.094) and G/C16 (IVW: OR (95% CI) = 0.886 (0.832 to 0.943) were identified as pivotal exposure factors for PA. CONCLUSIONS: This study highlights 10 plasma metabolites that may have significant associations with PA incidence, with 20:4n6 levels and G/C16 potentially serving as valuable biomarkers for the early detection and management of PA.

Humans↗

PubMed1998

The Health Belief Model and HIV risk behaviours: a causal model analysis among Anglos, African-Americans and Mexican-Americans.

A causal model of the Health Belief Model (HBM) is empirically evaluated which emphasizes possible indirect paths linking distal demographic and seriousness/susceptibility variables to HIV risk behaviours among Anglo, African-American, and Mexican-American adults. A specific focus of the paper is upon alcohol-related expectancies (anticipation of disinhibitory effects of alcohol upon sexual behavior) as a 'barrier' to preventive behaviours. Ethnic comparisons stem both from the paucity of available research on the HBM in minority populations and from recent questions regarding the applicability of rational models such as the HBM among minority groups. Analyses of data from a community sample of 1390 adults indicate relatively consistent direct effects of barriers for males and benefits for females upon HIV risk behaviors. The analyses suggest distinct paths operative among males and females. The susceptibility-barriers-risk behaviours path among males may suggest that alcohol-related expectancies (barriers in this model) may be more strongly related to risk behaviours among males than minority females.

Adult↗

PubMed2003

Obesity and asthma: evidence for and against a causal relation.

The evidence for an association between asthma and obesity in adults, and in children and adolescents, is reviewed. Few studies in adults measured height and weight, whereas the majority in children did. Evidence for the association is strong, but that for a gender interaction is weak. There is sufficient evidence to rule out asthma preceding obesity as an explanation, and that increased perception of symptoms in the obese, or a purely mechanical effect, is responsible. However, direct causality is unlikely, because in children the association is of recent origin, and trends in obesity do not explain the rising prevalence of asthma. Atopy was not associated with obesity in a large adult study. Potential explanations that require further investigation are that gastroesophageal reflux as a result of obesity causes asthma, that physical inactivity may promote both obesity and asthma, and that the diets of obese subjects may potentiate asthma.

Adolescent↗

PubMed2006

Limits to causal inference based on Mendelian randomization: a comparison with randomized controlled trials.

"Mendelian randomization" refers to the random assortment of genes transferred from parent to offspring at the time of gamete formation. This process has been compared to a randomized controlled trial of genetic variants. This could greatly aid observational epidemiology by potentially allowing an unbiased estimate of the effects of gene products on disease outcomes. However, studies utilizing Mendelian randomization to estimate effects of gene products on outcomes should be interpreted with caution. In this paper, the authors discuss some of the challenges facing epidemiologists in the analysis and interpretation of Mendelian randomization studies, particularly those that become apparent when the analogy with randomized controlled trials is closely examined. The authors conclude that Mendelian randomization is a powerful addition to etiologic research tools. However, care must be taken, because drawing valid causal inferences from its application depends upon more extensive assumptions than are required in randomized controlled trials.

Causality↗

PubMed2006

Birth weight and mortality: causality or confounding?

The association between birth weight and mortality is among the strongest seen in epidemiology. While preterm delivery causes both small babies and high mortality, it does not explain this association. Fetal growth restriction has also been proposed, although its features are unclear because it lacks a definition independent of weight. If, as some postulate, birth weight is not itself on the causal path to mortality, its relation with mortality would have to be explained by confounding factors that decrease birth weight and increase mortality. In this paper, the authors explore the characteristics such confounders would require in order to achieve the observed association between birth weight and mortality. Through a simple simulation, they found that the observed steep gradient of risk for small babies at term can be produced by a rare condition or conditions (with a total prevalence of 0.5%) having profound effects on both fetal growth (-1.7 standard deviations) and mortality (relative risk = 160). Candidate conditions might include malformations, fetal or placental aneuploidy, infections, or imprinting disorders. If such rare factors underlie the association of birth weight with mortality, it would have broad implications for the study of fetal growth restriction and birth weight, and for the prevention of infant mortality.

Birth Weight↗

PubMed1993

Towards causal inference in occupational cancer epidemiology--II. Getting the count right.

This second paper in the series assessing causal inference in occupational cancer epidemiology highlights the importance of using the right data sources when examining the association between exposure and tumour incidence in groups of workers. Using the wrong ones can lead to omissions which become insidious and cumulative during a long-term follow-up study, often extending over several decades. The main cause is the changing survival pattern of some cancers and it is a new and important factor to be taken into account. This was illustrated during an in-depth study of an excess of bladder cancer at a large tire factory, where the workforce was exposed to beta-naphthylamine-contaminated antioxidants used in processing. At first the study was confined to a mortality analysis using death certificates to identify those whose underlying cause of death was bladder cancer [International Classification of Diseases (8th Rev.), No. 188]. It soon became apparent, however, that several cases had outlived the study end-date, or had died of an unrelated cause, often with bladder cancer not being mentioned anywhere on the death certificate. The study was then changed also to include morbidity (incidence) data using cancer registration. Between 1946 and 1949 some 2090 men were exposed to two antioxidants contaminated with about 0.2% of beta-naphthylamine. Altogether there were 45 bladder tumours relevant to this 'at risk' group, whereas only 24.8 were expected at the national incidence rates (P < 0.001), which clearly reflects the group's exposure to a recognized bladder carcinogen.(ABSTRACT TRUNCATED AT 250 WORDS)

Causality↗

PubMed1994

Age differences in causal attributions from an adult developmental perspective.

Causal attributions for events varying on level of informational ambiguity, outcome valence (positive, negative), and situation (relationship, achievement) were examined among young, middle-aged, and older adults. Participants rated the degree to which a cause of an event was a function of the primary character, situation, or a combination of both (interactive attributions). All adults made interactive attributions for ambiguous events, dispositional attributions with increasing involvement of the primary character, and situational attributions with less involvement of the primary character. Older adults made more interactive attributions in relationship situations and more dispositional attributions in negative situations. For achievement situations, younger adults made more interactive attributions for ambiguous events.

Adult↗

PubMed1991

Specificity of association in analysis of mortality and inference on causality.

Specificity of association between putative risk factor and disease under study is important to inference on causality. Nevertheless many studies investigate mortality of a single disease without comparison with a control. Age-standardized proportional mortality ratios make single disease studies into case-control studies and thus demonstrate whether or not associations are disease specific. Comparison of disease-specific with all-cause mortality experiences of whole populations classified by exposure, clearly distinguishes between exposures associated with more death and with earlier/younger death, thereby overcoming an important limitation of the familiar standardized mortality ratio (SMR). Smoking is associated with more death from lung cancer (lifetime cause-specific proportions, never 1%, light 6%, moderate 8% and heavy 12%) and with earlier/younger death from ischaemic heart disease (never 35%, light 34%, moderate 32% and heavy 29%).

Adult↗

PubMed2000

Causality and temporality in the study of short-term effects of air pollution on health.

BACKGROUND: The relationship between air pollution and health is usually analysed by time series analysis. However, temporality (i.e. looking to see whether the cause precedes the effect) is rarely examined in detail. METHODS: Models were fitted to daily levels of black smoke, nitrogen dioxide, sulphur dioxide, ozone and mortality from Barcelona 1986-1995 to account for seasonality, environmental temperature, days of the week and influenza epidemics. Cross-correlations of the residuals were plotted for different lags. RESULTS: Clear evidence of a temporal relationship between mortality and air pollution found for all four pollutants in that changes in the pollutant preceded changes in mortality, implying causality. However the pattern of dependence was different for each pollutant. CONCLUSION: The cross-correlation plot is a useful tool in the analysis of air pollution time series.

Air Pollution↗

PubMed1992

Assessing the direction of causality in cross-sectional studies.

Interpretation of observational studies is difficult, particularly in cross-sectional studies, because the direction of cause and effect may be difficult to assess: Did the "outcome" affect the measured exposure level, or did the exposure affect the outcome? In this paper, the authors describe a pattern, the "checkmark pattern," which can arise in cross-sectional studies. This pattern is characterized by higher levels of the outcome in an unexposed comparison group than in some subgroups of the exposed. The pattern, if seen in certain types of observational studies, suggests that the "outcome" variable may have affected the measured exposure level. Recognition of the pattern may help the epidemiologist to decipher the causal sequence. Two examples illustrate the issues involved.

Adipose Tissue↗

PubMed2000

Marginal structural models and causal inference in epidemiology.

In observational studies with exposures or treatments that vary over time, standard approaches for adjustment of confounding are biased when there exist time-dependent confounders that are also affected by previous treatment. This paper introduces marginal structural models, a new class of causal models that allow for improved adjustment of confounding in those situations. The parameters of a marginal structural model can be consistently estimated using a new class of estimators, the inverse-probability-of-treatment weighted estimators.

Anti-HIV Agents↗

PubMed2002

Understanding the causal relationship between patient-reported interpersonal and technical quality of care for depression.

OBJECTIVES: Patient ratings of their health care experience have become increasingly important as indicators of interpersonal quality of care. Currently the link between technical and interpersonal quality of care indicators is not well understood. The goal of this study was to examine the temporal relationship between technical quality of care for depression and interpersonal quality of care by examining their association over time. METHODS: A cross-lagged (longitudinal) path analytic model was estimated to examine the causal relationship between two measures of interpersonal quality of care and technical quality of care among 697 respondents participating in the 18 and 24 month assessments of Partners in Care (PIC). Measures of age, gender, number of chronic diseases, indicators of anxiety and depression, recent service utilization, and stability of the doctor-patient relationship were included as covariates. RESULTS: After controlling for study design and relevant patient characteristics, one significant cross-lagged effect was found: that from one measure of interpersonal quality (patient satisfaction) to technical quality (standardized coefficient = 0.18), but not from quality to satisfaction. CONCLUSION: Results of these analyses indicate that patients who report high satisfaction with care are more likely to receive higher technical quality depression care 6 months later as compared with those who are less satisfied. This implies that one pathway to improving technical quality of care may be through increasing patients' satisfaction.

Adult↗

PubMedDate not supplied

Relationships of work and practice environment to professional burnout: testing a causal model.

BACKGROUND: Research has established clear links between nurses' experience of professional burnout and many qualities of work environments but more work is needed to clarify interrelationships among aspects of complex organizational settings. OBJECTIVE: To test a nursing worklife model that defined structured relationships among professional practice environment qualities and burnout. METHODS: Hospital-based nurses in Canada (N = 8,597) completed an assessment of worklife (Nursing Work Index, NWI) and burnout (Maslach Burnout Inventory-Human Service Scale, MBI-HSS). RESULTS: A causal model was used to confirm the factor structure of the Professional Environment Scale (NWI-PES) on a subset of NWI items and the factor structure of the MBI-HSS. The analysis provided support for a structural model (nursing worklife model) linking the five worklife factors used to define a fundamental role for nursing leadership in determining the quality of worklife regarding policy involvement, staffing levels, support for a nursing model of care, and physician-nurse relationships. The analysis supported a direct path (negatively weighted) from staffing to emotional exhaustion and a direct path (positively weighted) from nursing model of care to personal accomplishment. DISCUSSION: Implications for refining a model of worklife are discussed. Implications for enhancing the quality of worklife and supporting engagement with work are considered.

Adult↗