scholarly journals A Powerful Gene-Based Test Accommodating Common and Low-Frequency Variants to Detect Both Main Effects and Gene-Gene Interaction Effects in Case-Control Studies

2018 ◽  
Vol 8 ◽  
Author(s):  
Ren-Hua Chung ◽  
Chen-Yu Kang
Keyword(s):  
Low Frequency ◽  
Gene Interaction ◽  
Interaction Effects ◽  
Case Control ◽  
Case Control Studies ◽  
Main Effects

Adverse cardiovascular events associated with triptans and ergotamines for treatment of migraine: Systematic review of observational studies

Cephalalgia ◽  
2014 ◽  
Vol 35 (2) ◽  
pp. 118-131 ◽  
Author(s):  
G Roberto ◽  
E Raschi ◽  
C Piccinni ◽  
V Conti ◽  
L Vignatelli ◽  
...  
Keyword(s):  
Observational Studies ◽  
Stroke Risk ◽  
Data Extraction ◽  
Low Frequency ◽  
Case Control ◽  
Cochrane Library ◽  
Case Control Studies ◽  
Safety Issues ◽  
Increased Risk ◽  
Ischemic Events

Background Apart from the underlying cardiovascular (CV) risk associated with migraine, both triptans and ergotamines can induce vasoconstriction and potentially increase the risk of serious ischemic events. Because of the low frequency of such events in eligible patients, randomized controlled trials are not exhaustive to assess the drug-related CV risk. Observational studies are, therefore, an essential source of information to clarify this matter of concern. Aim The aim of this study was to systematically review the available published observational studies investigating the risk of serious CV events in triptan or ergotamine users, as compared to unexposed migraineur controls. Methods We systematically searched MEDLINE and EMBASE electronic databases for cohort or case-control studies up to December 1, 2013. Studies retrieved from CDSR, DARE and HTA databases of the Cochrane Library were used for snowballing. Studies investigating the risk of any CV outcome in patients with a migraine diagnosis and exposed to triptans or ergotamines were considered for inclusion. Selection of studies, data extraction, and risk of bias assessment were conducted independently by two reviewers. Pooled odds ratios (ORs) with 95% confidence interval (95% CI) were computed using a random-effects model for studies and outcomes judged eligible for quantitative data synthesis. Results From a total of 3370 citations retrieved, after duplicate removal and screening, only four studies met the inclusion criteria (three nested case-control analyses and one retrospective cohort study). These studies investigated the risk of different CV outcomes associated with either the recency or the intensity of exposure to the studied drugs. As for the intensity of use, the pooled OR of serious ischemic events was 2.28 (95% CI 1.18–4.41; I2 = 0%) for ergotamine use (two studies), whereas for triptans (three studies) it was 0.86 (95% CI 0.52–1.43; I2 = 24.5%). Recent use of ergotamines was not significantly associated with any CV outcome (only one available study). Two studies investigated the risk of stroke related to recent triptan use: the first study reported an OR of 0.90 (0.64–1.26), and the second one suggested an increased risk of 2.51 (1.10–5.71). In this case, because of the high degree of heterogeneity, results were not pooled. Conclusions To date, few comparative observational studies have investigated the CV safety of migraine-specific drugs in clinical practice. Evidence gathered here suggests that intense consumption of ergotamines may be associated with an increased risk of serious ischemic complications. As for triptans, available studies do not suggest strong CV safety issues, although no firm conclusions can be drawn. In particular, evidence on stroke risk is conflicting. However, if an increase of the absolute stroke risk in recently exposed patients does actually exist, it must be small. Overall, residual uncontrolled confounding factors reduce the confidence in the risk estimates collected from the included studies. Further investigations are needed to better define the risk for rare but serious CV events related to triptan and ergotamine use for treatment of migraine.

scholarly journals Magnetic fields and acute lymphoblastic leukemia in children: a systematic review of case-control studies

2009 ◽  
Vol 25 (suppl 3) ◽  
pp. S441-S452 ◽  
Author(s):  
Daniele Maria Pelissari ◽  
Flávio Eitor Barbieri ◽  
Victor Wünsch Filho
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
Magnetic Fields ◽  
Childhood Leukemia ◽  
Lymphoblastic Leukemia ◽  
Low Frequency ◽  
Case Control ◽  
Case Control Studies ◽  
Future Studies ◽  
Current Article ◽  
Leukemia In Children

Leukemia incidence in children has increased worldwide in recent decades, particularly due to the rise in acute lymphoblastic leukemia. Studies have associated exposure to non-ionizing radiation generated by low frequency magnetic fields with childhood leukemia. The current article reviews the case-control studies published on this subject. Of 152 articles tracked in different databases, ten studies from North America, Asia, and Europe met the defined selection criteria, with patients diagnosed from 1960 to 2004. Methodological limitations were observed in these articles, including difficulties with the procedures for assessing exposure. An association may exist between exposure to low frequency magnetic fields and acute lymphoblastic leukemia in children, but this association is weak, preventing the observation of consistency in the findings. Future studies from a wider range of geographic regions should focus on the analysis of acute lymphoblastic leukemia, which is the subtype with the greatest impact on the increasing overall incidence of childhood leukemia.

scholarly journals Case-Control Study on Occupational Exposure to Extremely Low-Frequency Electromagnetic Fields and the Association with Meningioma

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Michael Carlberg ◽  
Tarmo Koppel ◽  
Mikko Ahonen ◽  
Lennart Hardell
Keyword(s):  
Electromagnetic Fields ◽  
Childhood Leukemia ◽  
Linear Trend ◽  
Low Frequency ◽  
Case Control ◽  
Cumulative Exposure ◽  
International Agency ◽  
Case Control Studies ◽  
Extremely Low Frequency ◽  
Increased Risk

Objective. Exposure to extremely low-frequency electromagnetic fields (ELF-EMF) was in 2002 classified as a possible human carcinogen, Group 2B, by the International Agency for Research on Cancer at WHO based on an increased risk for childhood leukemia. In case-control studies on brain tumors during 1997–2003 and 2007–2009 we assessed lifetime occupations in addition to exposure to different agents. The INTEROCC ELF-EMF Job-Exposure Matrix was used for associating occupations with ELF-EMF exposure (μT) with meningioma. Cumulative exposure (μT-years), average exposure (μT), and maximum exposed job (μT) were calculated. Results. No increased risk for meningioma was found in any category. For cumulative exposure in the highest exposure category 8.52+ μT years odds ratio (OR) = 0.9, 95% confidence interval (CI) = 0.7–1.2, and p linear trend = 0.45 were calculated. No statistically significant risks were found in different time windows. Conclusion. In conclusion occupational ELF-EMF was not associated with an increased risk for meningioma.

scholarly journals Sample Size Calculations for Main Effects and Interactions in Case–control Studies using Stata's nchi2 and npnchi2 Functions

2003 ◽  
Vol 3 (1) ◽  
pp. 47-56 ◽  
Author(s):  
Catherine L. Saunders ◽  
D. Timothy Bishop ◽  
Jennifer H. Barrett
Keyword(s):  
Sample Size ◽  
Null Hypothesis ◽  
Case Control ◽  
Case Control Studies ◽  
Gene Environment ◽  
Sample Size Calculations ◽  
Main Effects

The non-central X2 distribution can be used to calculate power for tests detecting departure from a null hypothesis. Required sample size can also be calculated because it is proportional to the non-centrality parameter for the distribution. We demonstrate how these calculations can be carried out in Stata using the example of calculating power and sample size for case–control studies of gene–gene and gene–environment interactions. Do-files are available for these calculations.

scholarly journals Allelic Based Gene-Gene Interaction in Case-Control Studies

2010 ◽  
Vol 69 (1) ◽  
pp. 14-27
Author(s):  
Jeesun Jung ◽  
Yiqiang Zhao
Keyword(s):  
Gene Interaction ◽  
Case Control ◽  
Case Control Studies

Case-Control Studies

2009 ◽  
Author(s):  
Ruth H. Keogh ◽  
D. R. Cox
Keyword(s):  
Case Control ◽  
Case Control Studies

Clinical Trials in Thrombosis: Secondary Prevention of Myocardial Infarction

1976 ◽  
Vol 35 (01) ◽  
pp. 049-056 ◽  
Author(s):  
Christian R Klimt ◽  
P. H Doub ◽  
Nancy H Doub
Keyword(s):  
Myocardial Infarction ◽  
Secondary Prevention ◽  
Case Control ◽  
Therapeutic Effects ◽  
Case Control Studies ◽  
Definitive Answer ◽  
Inhibition Of Platelet Aggregation ◽  
Prospective Trials

SummaryNumerous in vivo and in vitro experiments, investigating the inhibition of platelet aggregation and the prevention of experimentally-induced thrombosis, suggest that anti-platelet drugs, such as aspirin or the combination of aspirin and dipyridamole or sulfinpyrazone, may be effective anti-thrombotic agents in man. Since 1971, seven randomized prospective trials and two case-control studies have been referenced in the literature or are currently being conducted, which evaluate the effects of aspirin, sulfinpyrazone, or dipyridamole in combination with aspirin in the secondary prevention of myocardial infarction. A critical review of these trials indicates a range of evidence from no difference to a favorable trend that antiplatelet drugs may serve as anti-thrombotic agents in man. To date, a definitive answer concerning the therapeutic effects of these drugs in the secondary prevention of coronary heart disease is not available.

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