scholarly journals Collider Scope: When selection bias can substantially influence observed associations

2016 ◽  
Author(s):  
Marcus R. Munafò ◽  
Kate Tilling ◽  
Amy E. Taylor ◽  
David M. Evans ◽  
George Davey Smith
Keyword(s):  
Cohort Studies ◽  
Selection Bias ◽  
Large Scale ◽  
Sensitivity Analyses ◽  
Birth Cohort Study ◽  
Strong Impact ◽  
Cross Sectional ◽  
Polygenic Scores ◽  
Biased Estimates ◽  
Collider Bias

AbstractLarge-scale cross-sectional and cohort studies have transformed our understanding of the genetic and environmental determinants of health outcomes. However, the representativeness of these samples may be limited – either through selection into studies, or by attrition from studies over time. Here we explore the potential impact of this selection bias on results obtained from these studies, from the perspective that this amounts to conditioning on a collider (i.e., a form of collider bias). While it is acknowledged that selection bias will have a strong effect on representativeness and prevalence estimates, it is often assumed that it should not have a strong impact on estimates of associations. We argue that because selection can induce collider bias (which occurs when two variables independently influence a third variable, and that third variable is conditioned upon), selection can lead to substantially biased estimates of associations. In particular, selection related to phenotypes can bias associations with genetic variants associated with those phenotypes. In simulations, we show that even modest influences on selection into, or attrition from, a study can generate biased and potentially misleading estimates of both phenotypic and genotypic associations. Our results highlight the value of knowing which population your study sample is representative of. If the factors influencing selection and attrition are known, they can be adjusted for. For example, having DNA available on most participants in a birth cohort study offers the possibility of investigating the extent to which polygenic scores predict subsequent participation, which in turn would enable sensitivity analyses of the extent to which bias might distort estimates.Key MessagesSelection bias (including selective attrition) may limit the representativeness of large-scale cross-sectional and cohort studies.This selection bias may induce collider bias (which occurs when two variables independently influence a third variable, and that variable is conditioned upon).This may lead to substantially biased estimates of associations, including of genetic associations, even when selection / attrition is relatively modest.

scholarly journals The Comorbid Relationship Between Migraine and Asthma: A Systematic Review and Meta-Analysis of Population-Based Studies

2021 ◽  
Vol 7 ◽  
Author(s):  
Long Wang ◽  
Zi-Ru Deng ◽  
Mei-Dan Zu ◽  
Juan Zhang ◽  
Yu Wang
Keyword(s):  
Cohort Studies ◽  
Potential Risk ◽  
Meta Analysis ◽  
Population Based ◽  
Pooled Analysis ◽  
Sensitivity Analyses ◽  
Risk Indicator ◽  
Cross Sectional ◽  
Full Text Review ◽  
Newcastle Ottawa Scale

Objective: Recent studies have indicated a pathophysiologic link between migraine and asthma. This meta-analysis aimed to comprehensively estimate the risk ratio for migraine in asthma as well as that of asthma in migraine based on available evidence.Method: We systematically searched the electronic databases including PubMed, Web of Science, and SCOPUS for population-based studies that measured either the odds or the risk of asthma in subjects with migraine as well as that of migraine in subjects with asthma. The titles and abstracts were screened by two independent reviewers to identify eligible studies, and this was followed by full-text review of the included studies. Newcastle–Ottawa Scale (NOS) was used to assess the risk of bias of included literature. A meta-analysis was conducted with Review Manager 5.3 Software to calculate the odds ratio (OR) for case-control and cross-sectional studies and either relative ratio (RR) or hazard ratio (HR) for cohort studies, and the source of heterogeneity was assessed. Subgroup and sensitivity analyses were conducted, and the I2 test were used to assess the source of heterogeneity. The funnel plot, Galbraith plot, and Egger's test were used to evaluate publication bias.Results: Fifteen published studies covering a total of 1,188,780 individuals were identified. Pooled analysis indicated that migraine was associated with increased odds (OR = 1.54; 95% CI: 1.34~1.77) and risk for asthma (HR = 1.42; 95% CI: 1.26~1.60), and asthma associated with increased odds (OR = 1.45; 95% CI: 1.22~1.72) and risk for migraine (HR = 1.47; 95% CI: 1.41~1.52).Conclusion: Migraine is a potential risk indicator for asthma, and vice versa, asthma is a potential risk indicator for migraine. However, future prospective cohort studies are warranted to provide more evidence concerning the detailed association between migraine and asthma.

scholarly journals T112. PTSD AS A MEDIATOR OF THE RELATIONSHIP BETWEEN TRAUMA AND PSYCHOTIC EXPERIENCES

2020 ◽  
Vol 46 (Supplement_1) ◽  
pp. S273-S273
Author(s):  
Daniela Strelchuk ◽  
Gemma Hammerton ◽  
Jazz Croft ◽  
Jon Heron ◽  
Stanley Zammit ◽  
...  
Keyword(s):  
Childhood Trauma ◽  
Traumatic Event ◽  
Early Adulthood ◽  
Trauma Exposure ◽  
Sensitivity Analyses ◽  
Birth Cohort Study ◽  
Ptsd Symptoms ◽  
Psychotic Experiences ◽  
Cross Sectional ◽  
The Relationship

Abstract Background Trauma exposure is linked to the development of psychotic illnesses, but little is known about potentially modifiable mechanisms underlying this relationship. Despite the high prevalence of PTSD symptoms in psychotic illnesses, only a few studies have examined the role of PTSD as a mediator, and these were all cross-sectional. This study aims to examine whether PTSD symptoms mediate the relationship between trauma and psychotic experiences (PE), using data from a large birth cohort study. Methods We used data from the Avon Longitudinal Study of Parents and Children (ALSPAC) to test whether: a) PTSD symptoms (at age 15) mediate the relationship between childhood trauma (age 0–14 years) and adolescent frequent or distressing psychotic experiences (age 12–18 years) (study of adolescent PE; n = 2,952), and b) PTSD symptoms (reported at age 24 for traumatic event occurring before age 19) mediate the relationship between childhood/adolescent trauma (age 0–17 years) and incident frequent or distressing psychotic experiences in early adulthood (age 19–24 years) (study of adult PE; n = 2,492). Associations between the variables of interest were examined with logistic regression, and mediation with the parametric g-computation formula. As sensitivity analyses, we i) examined broader and narrower psychotic outcomes, ii) included a measure of psychotic-like experiences at age 14 years as an intermediate confounder in the mediation model for adolescent psychotic experiences, and iii) repeated analyses using imputed data. Results Exposure to trauma was associated with increased odds of psychotic experiences and PTSD symptoms both in adolescence and early adulthood (p<0.001). The association between PTSD and psychotic experiences was stronger in adolescence (p<0.001) than in adulthood (p=0.03). There was moderate evidence that PTSD symptoms mediated the relationship between childhood trauma and adolescent psychotic experiences (proportion mediated 14%), though evidence of mediation was much weaker for adult PE (proportion mediated 8%). In sensitivity analyses we observed similar results when using imputed data, and when modelling psychotic experiences at age 14 as an intermediate confounding for the adolescent PE outcome. The proportion mediated increased when examining more narrowly defined outcomes (19% for adolescent psychotic disorder). Discussion These findings provide some evidence consistent with the thesis that psychotic experiences and disorder can occur consequent to PTSD symptoms after trauma exposure. Targeting PTSD symptoms might help prevent the occurrence of psychotic experiences and disorder in people with a trauma history.

scholarly journals Relationship between Chronic Periodontitis and Erectile Dysfunction: A Narrative Review

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Jaffer A. Shariff ◽  
Aparna Ingleshwar ◽  
Kevin C. Lee ◽  
Athanasios I. Zavras
Keyword(s):  
Erectile Dysfunction ◽  
Cohort Studies ◽  
Chronic Periodontitis ◽  
Large Scale ◽  
Periodontal Therapy ◽  
Narrative Review ◽  
Cochrane Library ◽  
Case Control Studies ◽  
Necrosis Factor Alpha ◽  
Cross Sectional

Objective. To conduct a descriptive literature review on research studies investigating the association between chronic periodontitis (CP) and erectile dysfunction (ED). Methods. Cohort studies, case-control studies, cross-sectional studies, randomized control trials, and animal studies up to July 2015 that studied the relationship between CP and ED were reviewed and reported. Data sources included PubMed, EMBASE, Cochrane Library, and Clinicaltrials.gov. The themes “periodontal disease” and “erectile dysfunction” and the role of periodontal therapy were identified and discussed throughout the narrative review. Results. After reviewing the literature, it was found that an association between CP and vasculogenic ED likely exists. Inflammation resulting from CP promotes endothelial dysfunction by increasing the systemic levels of inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α). Periodontal therapy attempts to decrease the release of TNF-α and could act to restore endothelial function, particularly in the penile vasculature. Conclusion. Although the literature reported a positive association between CP and ED, the studies were few and possess several methodological limitations. Large-scale cohort studies and confounder analysis are recommended. Dentists and physicians should collaborate to manage patients with either CP or ED because of their potential association not only with each other but also with other serious systemic comorbidities.

scholarly journals The Risk of Rheumatoid Arthritis among Patients with Inflammatory Bowel Disease: A Systematic Review and Meta-analysis

2020 ◽  
Author(s):  
Yi Chen ◽  
Lang Chen ◽  
Changsheng Xing ◽  
Guangtong Deng ◽  
Furong Zeng ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Inflammatory Bowel Disease ◽  
Cohort Studies ◽  
Bowel Disease ◽  
Meta Analysis ◽  
Sensitivity Analyses ◽  
Cross Sectional ◽  
Relative Risks ◽  
Increased Risk ◽  
Inflammatory Bowel

Abstract Background: Studies have suggested that patients with inflammatory bowel disease (IBD) have an increased risk of rheumatoid arthritis (RA). However, the available data on this association are inconsistent. This meta-analysis aimed to determine the association between IBD and the risk of RA. Methods: Observational studies investigating the RA risk among patients with IBD (Crohn disease (CD) and/or ulcerative colitis (UC)) were searched in PubMed, Embase, and Web of Science from the date of inception to December 2019 . The methodological quality of the included studies was assessed using the Newcastle-Ottawa Scale. Relative risks (RRs) and corresponding 95% confidential intervals (CIs) were pooled with a random-effects model. Heterogeneity was evaluated using I 2 statistics while publication bias was determined using Begg’s and Egger’s tests. Subgroup and sensitivity analyses were performed. Results: A total of three cohort studies, three cross-sectional studies, and two case-control study were included in the meta-analyses. Compared to the non-IBD control or general population, there was a significantly higher risk of RA among patients with IBD (RR=2.59; 95% CI: 1.93–3.48). Moreover, both CD (RR=3.14; 95% CI: 2.46–4.01) and UC (RR=2.29; 95% CI: 1.76–2.97) were associated with a significantly increased risk of RA . However, heterogeneity was substantial across studies and the subgroup analyses failed to identify the potential source of heterogeneity. Conclusions: Patients with IBD have a greater risk of developing RA. Rheumatologists should be consulted when patients with IBD present with undifferentiated joint complaints. However, more prospective cohort studies are needed to validate these results.

scholarly journals The Risk of Rheumatoid Arthritis among Patients with Inflammatory Bowel Disease: A Systematic Review and Meta-analysis

2020 ◽  
Author(s):  
Yi Chen ◽  
Lang Chen ◽  
Changsheng Xing ◽  
Guangtong Deng ◽  
Furong Zeng ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Inflammatory Bowel Disease ◽  
Cohort Studies ◽  
Bowel Disease ◽  
Meta Analysis ◽  
Sensitivity Analyses ◽  
Cross Sectional ◽  
Relative Risks ◽  
Increased Risk ◽  
Inflammatory Bowel

Abstract Background: Studies have suggested that patients with inflammatory bowel disease (IBD) have an increased risk of rheumatoid arthritis (RA). However, the available data on this association are inconsistent. This meta-analysis aimed to determine the association between IBD and the risk of RA. Methods: Observational studies investigating the RA risk among patients with IBD (Crohn disease (CD) and/or ulcerative colitis (UC)) were searched in PubMed, Embase, and Web of Science from the date of inception to December 2019. The methodological quality of the included studies was assessed using the Newcastle-Ottawa Scale. Relative risks (RRs) and corresponding 95% confidential intervals (CIs) were pooled with a random-effects model. Heterogeneity was evaluated using I2 statistics while publication bias was determined using Begg’s and Egger’s tests. Subgroup and sensitivity analyses were performed. Results: A total of three cohort studies, three cross-sectional studies, and two case-control study were included in the meta-analyses. Compared to the non-IBD control or general population, there was a significantly higher risk of RA among patients with IBD (RR=2.59; 95% CI: 1.93–3.48). Moreover, both CD (RR=3.14; 95% CI: 2.46–4.01) and UC (RR=2.29; 95% CI: 1.76–2.97) were associated with a significantly increased risk of RA. However, heterogeneity was substantial across studies and the subgroup analyses failed to identify the potential source of heterogeneity. Conclusions: Patients with IBD have a greater risk of developing RA. Rheumatologists should be consulted when patients with IBD present with undifferentiated joint complaints. However, more prospective cohort studies are needed to validate these results.

Association of Vitamin D Status With Liver and Kidney Disease: A Systematic Review of Clinical Trials, and Cross-Sectional and Cohort Studies

2019 ◽  
pp. 1-13 ◽  
Author(s):  
Seyed Mostafa Parizadeh ◽  
Majid Rezayi ◽  
Reza Jafarzadeh-Esfehani ◽  
Amir Avan ◽  
Hamideh Ghazizadeh ◽  
...  
Keyword(s):  
Vitamin D ◽  
Kidney Disease ◽  
Renal Disease ◽  
Cohort Studies ◽  
Cochrane Library ◽  
Major Public Health Problem ◽  
Vitamin D Status ◽  
Cross Sectional ◽  
Beneficial Effects ◽  
Vitamin D Levels

Abstract. Background: Vitamin D deficiency (VDD) is a major public health problem. There are few comprehensive systematic reviews about the relationship between Vitamin D status and liver and renal disease in Iran. Methods: We systemically searched the following databases: Web of Science; PubMed; Cochrane Library; Scopus; Science Direct; Google Scholar and two Iranian databases (Scientific Information Database (SID) and IranMedex) up until November 2017 to identify all randomized control trials (RCTs), case control, cross-sectional and cohort studies investigating the association between vitamin D and any form of liver or kidney disease. Results: Vitamin D insufficiency, or deficiency (VDD), is highly prevalent in Iran, reports varying between 44.4% in Isfahan to 98% in Gorgan. There is also a high prevalence of VDD among patients with liver or kidney disease, and the administration of vitamin D supplements may have beneficial effects on lipid profile, blood glucose, liver function and fatty liver disease, and bone health. Low serum vitamin D levels are related with abnormalities in these laboratory and clinical parameters. Conclusion: VDD is prevalent in patients with chronic liver or renal disease in Iran. There appear to be several beneficial effects of vitamin D supplementation in vitamin D deficient patients with liver or kidney disease.

Large-Scale Cross-Sectional Study of the Problem Areas in Diabetes Survey among Japanese Patients with Type 2 Diabetes Mellitus

Diabetes ◽  
2018 ◽  
Vol 67 (Supplement 1) ◽  
pp. 2393-PUB
Author(s):  
KENICHIRO TAKAHASHI ◽  
MINORI SHINODA ◽  
RIKA SAKAMOTO ◽  
JUN SUZUKI ◽  
TADASHI YAMAKAWA ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Type 2 Diabetes ◽  
Type 2 Diabetes Mellitus ◽  
Large Scale ◽  
Japanese Patients ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Cross Sectional ◽  
Diabetes Survey

Knowledge and awareness about MERS-CoV among the dental students in Chennai

2020 ◽  
Vol 11 (SPL1) ◽  
pp. 847-851
Author(s):  
Nithyanandham Masilamani ◽  
Dhanraj Ganapathy
Keyword(s):  
College Students ◽  
Large Scale ◽  
Preventive Measures ◽  
Positive Impact ◽  
Educational Programs ◽  
Dental Students ◽  
Professional Organizations ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Mode Of Transmission

Middle East Respiratory Syndrome (MERS) induced by new ß coronavirus MERS-(CoV) had first been described in Saudi Arabia in September 2012. MERS-CoV communication inside the population is often identified with clustered households and cramped communal spaces. The purpose of the study is to assess the knowledge and awareness of MERS-CoV among dental students in India. This was a questionnaire-based cross-sectional survey of 100 dental college students in Chennai. The self-designed questionnaires contained ten questions focused on the knowledge and awareness of MERS-CoV amongst dental college students. Questionnaires were circulated through an online website survey planet. After the responses were received from 100 participants, data were collected and analyzed, .87% are aware of MERS-CoV through media 13% from professional channels. 84%are aware of the clinical manifestation of MERS-CoV. 81%Are aware of the mode of transmission of MERS-CoV. 76%are aware of the preventive measures against MERS -CoV.68%. Are aware of the incubation period of MERS-CoV. 74%aware of PCR as a diagnostic test for MERS-CoV. This study concluded that dental students had strong awareness and knowledge of MERS. Also, there are a few differences in information and behaviours that require change. Large-scale health educational programs on MERS also should be facilitated by professional organizations to expand their reach and to strengthen knowledge to have a positive impact on their behaviour.

Gambling-like video game practices: A cross-sectional study of links with problem gambling and disordered gaming

2019 ◽  
Author(s):  
David Zendle
Keyword(s):  
Video Games ◽  
Problem Gambling ◽  
Video Game ◽  
Large Scale ◽  
Significant Degree ◽  
Cross Sectional Study ◽  
Video Gaming ◽  
Cross Sectional ◽  
Streaming Services ◽  
Clinically Significant

A variety of practices have recently emerged which are related to both video games and gambling. Most prominent of these are loot boxes. However, a broad range of other activities have recently emerged which are also related to both gambling and video games: esports betting, real-money video gaming, token wagering, social casino play, and watching videos of both loot box opening and gambling on game streaming services like Twitch.Whilst a nascent body of research has established the robust existence of a relationship between loot box spending and both problem gambling and disordered gaming, little research exists which examines whether similar links may exist for the diverse practices outlined above. Furthermore, no research has thus far attempted to estimate the prevalence of these activities.A large-scale survey of a representative sample of UK adults (n=1081) was therefore conducted in order to investigate these issues. Engagement in all measured forms of gambling-like video game practices were significantly associated with both problem gambling and disordered gaming. An aggregate measure of engagement was associated with both these outcomes to a clinically significant degree (r=0.23 and r=0.43). Engagement in gambling-like video game practices appeared widespread, with a 95% confidence interval estimating that 16.3% – 20.9% of the population engaged in these activities at least once in the last year. Engagement in these practices was highly inter-correlated: Individuals who engaged in one practice were likely to engage in several more.Overall, these results suggest that the potential effects of the blurring of lines between video games and gambling should not primarily be understood to be due to the presence of loot boxes in video games. They suggest the existence of a convergent ecosystem of gambling-like video game practices, whose causal relationships with problem gambling and disordered gaming are currently unclear but must urgently be investigated.

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