The results obtained from studies of causation

2017 ◽  
Author(s):  
Mark Elwood
Keyword(s):  
Relative Risk ◽  
Intervention Studies ◽  
Case Control ◽  
Risk Difference ◽  
Attributable Risk ◽  
Number Needed To Treat ◽  
Case Control Studies ◽  
Sampling Schemes ◽  
Multiplicative Models ◽  
The Relationship

This chapter shows the format and derivation of results from studies. Cohort and intervention studies yield relative risk and risk difference, also known as attributable risk, and number needed to treat (NNT). Count and person-time methods are shown. Additive and multiplicative models for two or more exposures are shown. Case-control studies give primarily odds ratio; the relationship between this and relative risk is explained. Different sampling schemes for case-control studies include methods were a case can also be a control. Surveys yield results similar to cohort studies.

Risky Business: Making Sense of Estimates of Risk

1998 ◽  
Vol 43 (4) ◽  
pp. 411-415 ◽  
Author(s):  
David L Streiner
Keyword(s):  
Relative Risk ◽  
Odds Ratio ◽  
Risk Difference ◽  
Attributable Risk ◽  
Absolute Difference ◽  
Number Needed To Treat ◽  
Making Sense ◽  
Specific Outcome ◽  
Relative Differences ◽  
Risky Business

This article describes various indices of risk, which is the probability that a person will develop a specific outcome. The risk difference is the absolute difference in risks between 2 groups and can be used either to compare the outcome of 2 groups, one of which was exposed to some genetic or environmental factor, or to see how much of an effect a treatment may have. The reciprocal of the risk difference, the number needed to treat, expresses how many patients must receive the intervention in order for 1 person to derive some benefit. Attributable risk reflects the proportion of cases due to some putative cause and indicates the number of cases that can be averted if the cause were removed. Finally, the relative risk and odds ratio reflect the relative differences between groups in achieving some outcome, either good (a cure) or bad (development of a disorder).

scholarly journals Understanding interactions between risk factors, and assessing the utility of the additive and multiplicative models through simulations

2019 ◽  
Author(s):  
Lina-Marcela Diaz-Gallo ◽  
Boel Brynedal ◽  
Helga Westerlind ◽  
Rickard Sandberg ◽  
Daniel Ramsköld
Keyword(s):  
Risk Factors ◽  
Relative Risk ◽  
Disease Risk ◽  
Interaction Analysis ◽  
Threshold Model ◽  
Real Data ◽  
Case Control ◽  
Case Control Studies ◽  
Set Up ◽  
Multiplicative Models

ABSTRACTInteraction analysis is used to investigate the magnitude of an effect which two risk factors have on disease risk, and on each other. To study interactions, both additive and multiplicative models have been used, although their interpretations are not universally understood. In this study, we set out to investigate the resulting interactions of several risk factors relationships in additive or multiplicative scenarios using simulations, in the context of case-control studies. Our simulation set up showed that independent risk factors approach additive relative risk at low disease prevalence. However, risk factors that contribute to the same chain of events (i.e. have synergy) lead to multiplicative relative risk. Additionally, thresholds on the number of required risk factors for a disease (the multifactorial threshold model) lead to intermediaries between additive and multiplicative risks. We proposed a novel measure of interaction consistent with additive, multiplicative and multifactorial threshold models. Finally, we demonstrate the utility of the simulation strategy and discovered relationships on real data by analyzing and interpreting gene-gene odds ratios from a case-control rheumatoid arthritis study.

scholarly journals Subcortical ischemic vascular disease and cognition: A systematic review

2008 ◽  
Vol 2 (2) ◽  
pp. 82-90 ◽  
Author(s):  
Gilberto Sousa Alves ◽  
Carlos Eduardo de Oliveira Alves ◽  
Maria Elisa Lanna ◽  
Denise Madeira Moreira ◽  
Eliasz Engelhardt ◽  
...  
Keyword(s):  
Vascular Disease ◽  
Memory Retrieval ◽  
White Matter Lesions ◽  
Case Control ◽  
Cognitive Status ◽  
Independent Factor ◽  
Case Control Studies ◽  
Cross Sectional ◽  
Cognitive Domains ◽  
The Relationship

Abstract Subcortical Ischemic Vascular Disease (SIVD) is underdiagnosed. This review investigates the relationship among SIVD severity, cognitive status and neuroimaging markers. Methods: Cohort, cross-sectional and case control studies were searched on ISI, Medline, Scielo, PsychoInfo and LILACS databases published between 1995 and 2006. Results: The most impaired cognitive domains were executive, attentional and memory retrieval mechanisms. These cognitive features were frequently associated to White Matter Lesions (WML). Conclusions: WML is an independent factor in cognitive decline. However, the threshold for this impact is not yet clearly established.

Assessment of the relationship between methylenetetrahydrofolate reductase polymorphism and acute lymphoblastic leukemia: Evidence from an updated meta-analysis

2020 ◽  
Vol 26 (7) ◽  
pp. 1598-1610
Author(s):  
Rim Frikha
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
Methylenetetrahydrofolate Reductase ◽  
Lymphoblastic Leukemia ◽  
Meta Analysis ◽  
Case Control ◽  
C677t Polymorphism ◽  
Case Control Studies ◽  
Gene Environment ◽  
Reductase Gene ◽  
The Relationship

Objective The methylenetetrahydrofolate reductase gene C677T polymorphism is closely related to the acute lymphoblastic leukemia. Several case–control studies have investigated this association; however, no conclusions could be drawn. A comprehensive updated meta-analysis is established to explain these contradictions and clarify the overall impact of this variant on the susceptibility to acute lymphoblastic leukemia. Methods Electronic searches were conducted to select published studies prior to June 2018. Pooled odds ratios and stratification analysis were performed under different genetic comparison models, age, and ethnicity. Results Totally, 66 case–control studies including 9619 acute lymphoblastic leukemia cases and 17,396 controls were selected. Our analyses showed that methylenetetrahydrofolate reductase C677T polymorphism was protective mainly in Asian and European countries, under all genetic models and regardless of age, but leukemogenic in mixed population. Conclusion Thus, C677T polymorphism may be a promising acute lymphoblastic leukemia biomarker, but they should be interpreted with caution considering other factors such as folic acid intake, gene–gene and gene–environment interactions.

scholarly journals Association of the MTHFR 677C>T and 1298A>C polymorphisms and male infertility risk: a meta-analysis

2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Fereshteh Aliakbari ◽  
Farkhondeh Pouresmaeili ◽  
Nahal Eshghifar ◽  
Zahra Zolghadr ◽  
Faezeh Azizi
Keyword(s):  
Male Infertility ◽  
Methylenetetrahydrofolate Reductase ◽  
Meta Analysis ◽  
Case Control ◽  
Inclusion Criteria ◽  
Case Control Studies ◽  
Crude Odds Ratio ◽  
Mthfr Polymorphism ◽  
Gene Environment ◽  
The Relationship

Abstract Background and objectives One of the possible male sterility risk factors are polymorphisms of Methylenetetrahydrofolate reductase (MTHFR). However, the epidemiologic investigations described inconsistent results regarding MTHFR polymorphism and the risk of male infertility. For that reason, we carried out a meta-analysis of published case-control studies to re-examine the controversy. Methods Electronic searches of Cochrane, EMBASE, Google Scholar, and PubMed were conducted to select eligible studies for this meta-analysis (updated to May 2019). According to our exclusion and inclusion criteria, only high-quality studies that remarked the association between MTHFR polymorphisms and male infertility risk were included. The Crude odds ratio (OR) with a confidence interval of 95% (CI) was used to assess the relationship between MTHFR polymorphism and male infertility risk. Results Thirty-four case-control studies with 9662 cases and 9154 controls concerning 677C/T polymorphism and 22 case-control studies with 5893 cases and 6303 controls concerning 1298A/C polymorphism were recruited. Both MTHFR polymorphisms had significant associations with male infertility risk (CT + TT vs. CC: OR = 1.37, 95% CI: 1.21–1.55, P = 0.00, I2 = 41.9%); (CC vs. CA + AA: OR = 0.82, 95% CI: 0.52–1.30, P = 0.04, I2 = 50.1%). Further, when stratified by ethnicity, the significant association results were observed in Asians and Caucasians for 677C/T and just Asians for 1298A/C. Conclusions Some of MTHFR polymorphisms like MTHFR 677C > T are associated with an elevated male infertility risk. To confirm our conclusion and to provide more accurate and complete gene-environment communication with male infertility risk, more analytical studies are needed.

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