scholarly journals Methodological limitations in experimental studies on symptom development in individuals with idiopathic environmental intolerance attributed to electromagnetic fields (IEI-EMF) – a systematic review

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Kristina Schmiedchen ◽  
Sarah Driessen ◽  
Gunnhild Oftedal
Keyword(s):  
Systematic Review ◽  
Electromagnetic Fields ◽  
Statistical Power ◽  
False Negative ◽  
Experimental Studies ◽  
Symptom Development ◽  
Nocebo Effect ◽  
Idiopathic Environmental Intolerance ◽  
Negative Results ◽  
Environmental Intolerance

Abstract Background Hypersensitivity to electromagnetic fields (EMF) is a controversial condition. While individuals with idiopathic environmental intolerance attributed to electromagnetic fields (IEI-EMF) claim to experience health complaints upon EMF exposure, many experimental studies have found no convincing evidence for a physical relation. The aim of this systematic review was to evaluate methodological limitations in experimental studies on symptom development in IEI-EMF individuals that might have fostered false positive or false negative results. Furthermore, we compared the profiles of these limitations between studies with positive and negative results. Methods The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guided the methodological conduct and reporting. Eligible were blinded experimental studies that exposed individuals with IEI-EMF to different EMF exposure levels and queried the development of symptoms during or after each exposure trial. Strengths and limitations in design, conduct and analysis of individual studies were assessed using a customized rating tool. Results Twenty-eight studies met the eligibility criteria and were included in this review. In many studies, both with positive and negative results, we identified methodological limitations that might have either fostered false or masked real effects of exposure. The most common limitations were related to the selection of study participants, the counterbalancing of the exposure sequence and the effectiveness of blinding. Many studies further lacked statistical power estimates. Methodically sound studies indicated that an effect of exposure is unlikely. Conclusion Overall, the evidence points towards no effect of exposure. If physical effects exist, previous findings suggest that they must be very weak or affect only few individuals with IEI-EMF. Given the evidence that the nocebo effect or medical/mental disorders may explain the symptoms in many individuals with IEI-EMF, additional research is required to identify the various factors that may be important for developing IEI-EMF and for provoking the symptoms. We recommend the identification of subgroups and exploring IEI-EMF in the context of other idiopathic environmental intolerances. If further experimental studies are conducted, they should preferably be performed at the individual level. In particular, to increase the likelihood of detecting hypersensitive individuals, if they exist, we encourage researchers to achieve a high credibility of the results by minimizing sources of risk of bias and imprecision.

scholarly journals The underestimated issue of non-reproducible cardiac troponin I and T results: case series and systematic review of the literature

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Julien Favresse ◽  
Jean-Louis Bayart ◽  
Damien Gruson ◽  
Sergio Bernardini ◽  
Aldo Clerico ◽  
...  
Keyword(s):  
Systematic Review ◽  
Clinical Judgment ◽  
Troponin I ◽  
Troponin T ◽  
Case Reports ◽  
False Negative ◽  
Case Series ◽  
Elevated Alkaline Phosphatase ◽  
Negative Results ◽  
Significant Difference

Abstract Cardiac troponins (cTn) are the preferred biomarkers for the evaluation of myocardial injury and play a key role in the diagnosis of acute myocardial infarction (MI). Pre-analytical or analytical issues and interferences affecting troponin T and I assays are therefore of major concern given the risk of misdiagnosis. False positive troponin results have been related to various interferences including anti-troponin antibodies, heterophilic antibodies, or elevated alkaline phosphatase level. On the other hand, false negative results have been reported in the case of a large biotin intake. These interferences are characterized with erroneous but reproducible troponin results. Of interest, non-reproducible results have also been reported in the literature. In other words, if the sample is reanalyzed a second time, a significant difference in troponin results will be observed. These interferences have been named “fliers” or “outliers”. Compared to the biotin interference that received major attention in the literature, troponin outliers are also able to induce harmful clinical consequences for the patient. Moreover, the prevalence of outliers in recent studies was found to be higher (0.28–0.57%) compared to the biotin interference. The aim of this systematic review is to warn clinicians about these non-reproducible results that may alter their clinical judgment. Four case reports that occurred in the Clinique of Saint-Luc Bouge are presented to attest this point. Moreover, we aimed at identifying the nature of these non-reproducible troponin results, determining their occurrence, and describing the best way for their identification.

scholarly journals Z-Curve

2017 ◽  
Author(s):  
Ulrich Schimmack ◽  
Jerry Brunner
Keyword(s):  
Selection Bias ◽  
Statistical Power ◽  
False Negative ◽  
Simulation Studies ◽  
Replication Studies ◽  
Negative Results ◽  
False Negative Results ◽  
Selection For ◽  
Z Curve ◽  
Substantial Heterogeneity

In recent years, the replicability of original findings published in psychology journals has been questioned. A key concern is that selection for significance inflates observed effect sizes and observed power. If selection bias is severe, replication studies are unlikely to reproduce a significant result. We introduce z-curve as a new method that can estimate the average true power for sets of studies that are selected for significance. We compare this method with p-curve, which has been used for the same purpose. Simulation studies show that both methods perform well when all studies have the same power, but p-curve overestimates power if power varies across studies. Based on these findings, we recommend z-curve to estimate power for sets of studies that are heterogeneous and selected for significance. Application of z-curve to various datasets suggests that the average replicability of published results in psychology is approximately 50%, but there is substantial heterogeneity and many psychological studies remain underpowered and are likely to produce false negative results. To increase replicability and credibility of published results it is important to reduce selection bias and to increase statistical power.

Idiopathic environmental intolerance attributed to electromagnetic fields (IEI-EMF) and electrosensibility (ES) – Are they connected?

2013 ◽  
Vol 216 (3) ◽  
pp. 362-370 ◽  
Author(s):  
Ferenc Köteles ◽  
Renáta Szemerszky ◽  
Mónika Gubányi ◽  
János Körmendi ◽  
Csaba Szekrényesi ◽  
...  
Keyword(s):  
Electromagnetic Fields ◽  
Idiopathic Environmental Intolerance ◽  
Environmental Intolerance
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