Search results for "Meta-analysis"
showing 10 items of 903 documents
A review of the importance of mineral nitrogen cycling in the plant-soil-microbe system of permafrost-affected soils : changing the paradigm
2022
The paradigm that permafrost-affected soils show restricted mineral nitrogen (N) cycling in favor of organic N compounds is based on the observation that net N mineralization rates in these cold climates are negligible. However, we find here that this perception is wrong. By synthesizing published data on N cycling in the plant-soil-microbe system of permafrost ecosystems we show that gross ammonification and nitrification rates in active layers were of similar magnitude and showed a similar dependence on soil organic carbon (C) and total N concentrations as observed in temperate and tropical systems. Moreover, high protein depolymerization rates and only marginal effects of C:N stoichiomet…
Computer-Mediated Communication, Social Media, and Mental Health: A Conceptual and Empirical Meta-Review
2020
Computer-mediated communication (CMC), and specifically social media, may affect the mental health (MH) and well-being of its users, for better or worse. Research on this topic has accumulated rapidly, accompanied by controversial public debate and numerous systematic reviews and meta-analyses. Yet, a higher-level integration of the multiple disparate conceptual and operational approaches to CMC and MH and individual review findings is desperately needed. To this end, we first develop two organizing frameworks that systematize conceptual and operational approaches to CMC and MH. Based on these frameworks, we integrate the literature through a meta-review of 34 reviews and a content analysi…
The relationship between internalized homonegativity and body image concerns in sexual minority men: a meta-analysis
2018
It remains unclear whether internalised homonegativity, a recognised predictor of internalising mental health problems, is related to body dissatisfaction in sexual minority men. We conducted a met...
Systemic risk factors for peri-implant bone loss: a systematic review and meta-analysis
2014
The aim of this study was to determine the influence of patient-related systemic risk factors (systemic disease, genetic traits, chronic drug or alcohol consumption, and smoking status) on peri-implant bone loss at least 1 year after implant installation and prosthetic loading. An electronic search was performed of MEDLINE, EMBASE, and The Cochrane Central Register of Controlled Trials up to January 2012. One thousand seven hundred and sixty-three studies were identified. After applying a three-stage screening process, 17 articles were included in the qualitative analysis, but only 13 in the quantitative analysis, since smoking was a common exposure. The meta-analysis of these 13 studies (4…
Don't throw away your printed books: A meta-analysis on the effects of reading media on reading comprehension
2018
Abstract With the increasing dominance of digital reading over paper reading, gaining understanding of the effects of the medium on reading comprehension has become critical. However, results from research comparing learning outcomes across printed and digital media are mixed, making conclusions difficult to reach. In the current meta-analysis, we examined research in recent years (2000–2017), comparing the reading of comparable texts on paper and on digital devices. We included studies with between-participants (n = 38) and within-participants designs (n = 16) involving 171,055 participants. Both designs yielded the same advantage of paper over digital reading (Hedge's g = −0.21; dc = −0.2…
Double counting individuals in meta-analysis artificially inflates precision. Comment on "Device-measured light-intensity physical activity and morta…
2019
Systematic Literature Reviews and Meta-Analyses
2009
SUMMARY Background: Because of the rising number of scientific publications, it is important to have a means of jointly summarizing and assessing different studies on a single topic. Systematic literature reviews, meta-analyses of published data, and meta-analyses of individual data (pooled reanalyses) are now being published with increasing frequency. We here describe the essential features of these methods and discuss their strengths and weaknesses. Methods: This article is based on a selective literature search. The different types of review and meta-analysis are described, the methods used in each are outlined so that they can be evaluated, and a checklist is given for the assessment of…
Scratching beneath 'The Scratching Case': systematic reviews and meta-analyses, the back door for evidence-based medicine
2014
Endometrial scratching or injury was first suggested a decade ago as a simple intervention to improve endometrial receptivity in patients undergoing ART. More than a decade later, based on weak evidence some doctors have adopted this strategy, although there is not yet agreement about its real benefit. In this opinion paper, we analyze the methodological and plausibility problem beneath 'the Scratching Case'. This is also applicable to several other examples of spurious associations reported in the literature. In particular, we emphasize what should be done so as not to dilute evidence-based medicine by a vicious circle created by the over-exploitation of inadequate or insufficient data to …
Effect of rapid maxillary expansion on sleep apnea-hypopnea syndrome in growing patients. A meta-analysis.
2019
Background Changes produced in the upper airway after rapid maxillary expansion makes this procedure a therapeutic option for treating sleep apnea-hypopnea syndrome (SAHS) in children. The objective of this systematic review and meta-analysis was to analyze the evidence available for the effects of rapid maxillary expansion (RME) on SAHS, analyzing changes produced in oximetric variables: apnea-hypopnea index (AHI); oxygen saturation (SO2); sleep efficiency (SE), total sleep time (TST), percentage of rapid eye movement (REM) phase; and arousal index (AI). Material and Methods An electronic search was conducted in the PubMed, Scopus, Embase, and Cochrane databases, and in grey literature (Op…
Heparin versus 0.9% sodium chloride intermittent flushing for prevention of occlusion in central venous catheters in adults
2014
Background Heparin intermittent flushing is a standard practice in the maintenance of patency in central venous catheters. However, we could find no systematic review examining its effectiveness and safety. Objectives To assess the effectiveness of intermittent flushing with heparin versus 0.9% sodium chloride (normal saline) solution in adults with central venous catheters in terms of prevention of occlusion and overall benefits versus harms. Search methods The Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched December 2013) and the Cochrane Central Register of Controlled Trials (CENTRAL) (2013, Issue 11). Searches were …