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John Pa Ioannidis

Thomas Pa Debray, Ewoud Schuit, Orestis Efthimiou, Johannes B Reitsma, John Pa Ioannidis, Georgia Salanti, Karel Gm Moons
Network meta-analysis (NMA) is a common approach to summarizing relative treatment effects from randomized trials with different treatment comparisons. Most NMAs are based on published aggregate data (AD) and have limited possibilities for investigating the extent of network consistency and between-study heterogeneity. Given that individual participant data (IPD) are considered the gold standard in evidence synthesis, we explored statistical methods for IPD-NMA and investigated their potential advantages and limitations, compared with AD-NMA...
August 2, 2016: Statistical Methods in Medical Research
Benjamin A Goldstein, Ann Marie Navar, Michael J Pencina, John Pa Ioannidis
OBJECTIVE: Electronic health records (EHRs) are an increasingly common data source for clinical risk prediction, presenting both unique analytic opportunities and challenges. We sought to evaluate the current state of EHR based risk prediction modeling through a systematic review of clinical prediction studies using EHR data. METHODS: We searched PubMed for articles that reported on the use of an EHR to develop a risk prediction model from 2009 to 2014. Articles were extracted by two reviewers, and we abstracted information on study design, use of EHR data, model building, and performance from each publication and supplementary documentation...
May 17, 2016: Journal of the American Medical Informatics Association: JAMIA
John Pa Ioannidis
No abstract text is available yet for this article.
June 2016: American Journal of Clinical Nutrition
Nazmus Saquib, Juliann Saquib, John P A Ioannidis
BACKGROUND: Several popular screening tests, such as mammography and prostate-specific antigen, have met with wide controversy and/or have lost their endorsement recently. We systematically evaluated evidence from randomized controlled trials (RCTs) as to whether screening decreases mortality from diseases where death is a common outcome. METHODS: We searched three sources: United States Preventive Services Task Force (USPSTF), Cochrane Database of Systematic Reviews, and PubMed...
February 2015: International Journal of Epidemiology
Ludovic Trinquart, John P A Ioannidis, Gilles Chatellier, Philippe Ravaud
BACKGROUND: Networks of trials assessing several treatment options available for the same condition are increasingly considered. Randomized trial evidence may be missing because of reporting bias. We propose a test for reporting bias in trial networks. METHODS: We test whether there is an excess of trials with statistically significant results across a network of trials. The observed number of trials with nominally statistically significant p-values across the network is compared with the expected number...
2014: BMC Medical Research Methodology
Shanthi Kappagoda, John P A Ioannidis
OBJECTIVE: To analyse evidence from randomized controlled trials (RCTs) on the prevention and control of neglected tropical diseases (NTDs) and to identify areas where evidence is lacking. METHODS: The Cochrane Central Register of Controlled Trials and PubMed were searched for RCTs and the Cochrane Database of Systematic Reviews and PubMed were searched for meta-analyses and systematic reviews, both from inception to 31 December 2012. FINDINGS: Overall, 258 RCTs were found on American trypanosomiasis, Buruli ulcer, dengue, geohelminth infection, leishmaniasis, leprosy, lymphatic filariasis, onchocerciasis, rabies, schistosomiasis or trachoma...
May 1, 2014: Bulletin of the World Health Organization
Joanna IntHout, John P A Ioannidis, George F Borm
BACKGROUND: The DerSimonian and Laird approach (DL) is widely used for random effects meta-analysis, but this often results in inappropriate type I error rates. The method described by Hartung, Knapp, Sidik and Jonkman (HKSJ) is known to perform better when trials of similar size are combined. However evidence in realistic situations, where one trial might be much larger than the other trials, is lacking. We aimed to evaluate the relative performance of the DL and HKSJ methods when studies of different sizes are combined and to develop a simple method to convert DL results to HKSJ results...
2014: BMC Medical Research Methodology
Vinay Prasad, John Pa Ioannidis
Abandoning ineffective medical practices and mitigating the risks of untested practices are important for improving patient health and containing healthcare costs. Historically, this process has relied on the evidence base, societal values, cultural tensions, and political sway, but not necessarily in that order. We propose a conceptual framework to guide and prioritize this process, shifting emphasis toward the principles of evidence-based medicine, acknowledging that evidence may still be misinterpreted or distorted by recalcitrant proponents of entrenched practices and other biases...
2014: Implementation Science: IS
Chirag J Patel, David H Rehkopf, John T Leppert, Walter M Bortz, Mark R Cullen, Glenn M Chertow, John Pa Ioannidis
BACKGROUND: Environmental and behavioural factors are thought to contribute to all-cause mortality. Here, we develop a method to systematically screen and validate the potential independent contributions to all-cause mortality of 249 environmental and behavioural factors in the National Health and Nutrition Examination Survey (NHANES). METHODS: We used Cox proportional hazards regression to associate 249 factors with all-cause mortality while adjusting for sociodemographic factors on data in the 1999-2000 and 2001-02 surveys (median 5...
December 2013: International Journal of Epidemiology
S Kanters, E J Mills, K Thorlund, H C Bucher, J P A Ioannidis
There have been over 100 randomized clinical trials (RCTs) of diverse regimens of antiretroviral therapy for treatment-naïve human immunodeficiency virus-positive patients. A further 400 systematic reviews and meta-analyses are informed by these trials. There are, however, difficulties in using systematic reviews and meta-analyses of this clinical evidence to inform guidelines and clinical practice. Several issues can make the interpretation of comparative effectiveness challenging. In this article, we review the key challenges in interpreting multiple trials in this population...
February 2014: Clinical Microbiology and Infection
Evangelos Evangelou, Hanneke J Kerkhof, Unnur Styrkarsdottir, Evangelia E Ntzani, Steffan D Bos, Tonu Esko, Daniel S Evans, Sarah Metrustry, Kalliope Panoutsopoulou, Yolande F M Ramos, Gudmar Thorleifsson, Konstantinos K Tsilidis, Nigel Arden, Nadim Aslam, Nicholas Bellamy, Fraser Birrell, Francisco J Blanco, Andrew Carr, Kay Chapman, Aaron G Day-Williams, Panos Deloukas, Michael Doherty, Gunnar Engström, Hafdis T Helgadottir, Albert Hofman, Thorvaldur Ingvarsson, Helgi Jonsson, Aime Keis, J Christiaan Keurentjes, Margreet Kloppenburg, Penelope A Lind, Andrew McCaskie, Nicholas G Martin, Lili Milani, Grant W Montgomery, Rob G H H Nelissen, Michael C Nevitt, Peter M Nilsson, William Er Ollier, Neeta Parimi, Ashok Rai, Stuart H Ralston, Mike R Reed, Jose A Riancho, Fernando Rivadeneira, Cristina Rodriguez-Fontenla, Lorraine Southam, Unnur Thorsteinsdottir, Aspasia Tsezou, Gillian A Wallis, J Mark Wilkinson, Antonio Gonzalez, Nancy E Lane, L Stefan Lohmander, John Loughlin, Andres Metspalu, Andre G Uitterlinden, Ingileif Jonsdottir, Kari Stefansson, P Eline Slagboom, Eleftheria Zeggini, Ingrid Meulenbelt, John Pa Ioannidis, Tim D Spector, Joyce B J van Meurs, Ana M Valdes
OBJECTIVES: Osteoarthritis (OA) is the most common form of arthritis with a clear genetic component. To identify novel loci associated with hip OA we performed a meta-analysis of genome-wide association studies (GWAS) on European subjects. METHODS: We performed a two-stage meta-analysis on more than 78,000 participants. In stage 1, we synthesised data from eight GWAS whereas data from 10 centres were used for 'in silico' or 'de novo' replication. Besides the main analysis, a stratified by sex analysis was performed to detect possible sex-specific signals...
December 2014: Annals of the Rheumatic Diseases
John Pa Ioannidis, Muin J Khoury
No abstract text is available yet for this article.
2013: Genome Medicine
Joanna IntHout, John Pa Ioannidis, George F Borm
There is debate whether clinical trials with suboptimal power are justified and whether results from large studies are more reliable than the (combined) results of smaller trials. We quantified the error rates for evaluations based on single conventionally powered trials (80% or 90% power) versus evaluations based on the random-effects meta-analysis of a series of smaller trials. When a treatment was assumed to have no effect but heterogeneity was present, the error rates for a single trial were increased more than 10-fold above the nominal rate, even for low heterogeneity...
April 2016: Statistical Methods in Medical Research
Ching-Ti Liu, Karol Estrada, Laura M Yerges-Armstrong, Najaf Amin, Evangelos Evangelou, Guo Li, Ryan L Minster, Melanie A Carless, Candace M Kammerer, Ling Oei, Yanhua Zhou, Nerea Alonso, Zoe Dailiana, Joel Eriksson, Natalia García-Giralt, Sylvie Giroux, Lise Bjerre Husted, Rita I Khusainova, Theodora Koromila, Annie Waichee Kung, Joshua R Lewis, Laura Masi, Simona Mencej-Bedrac, Xavier Nogues, Millan S Patel, Janez Prezelj, J Brent Richards, Pak Chung Sham, Timothy Spector, Liesbeth Vandenput, Su-Mei Xiao, Hou-Feng Zheng, Kun Zhu, Susana Balcells, Maria Luisa Brandi, Morten Frost, David Goltzman, Jesús González-Macías, Magnus Karlsson, Elza K Khusnutdinova, Panagoula Kollia, Bente Lomholt Langdahl, Osten Ljunggren, Mattias Lorentzon, Janja Marc, Dan Mellström, Claes Ohlsson, José M Olmos, Stuart H Ralston, José A Riancho, François Rousseau, Roser Urreizti, Wim Van Hul, María T Zarrabeitia, Martha Castano-Betancourt, Serkalem Demissie, Elin Grundberg, Lizbeth Herrera, Tony Kwan, Carolina Medina-Gómez, Tomi Pastinen, Gunnar Sigurdsson, Gudmar Thorleifsson, Joyce Bj Vanmeurs, John Blangero, Albert Hofman, Yongmei Liu, Braxton D Mitchell, Jeffrey R O'Connell, Ben A Oostra, Jerome I Rotter, Kari Stefansson, Elizabeth A Streeten, Unnur Styrkarsdottir, Unnur Thorsteinsdottir, Frances A Tylavsky, Andre Uitterlinden, Jane A Cauley, Tamara B Harris, John Pa Ioannidis, Bruce M Psaty, John A Robbins, M Carola Zillikens, Cornelia M Vanduijn, Richard L Prince, David Karasik, Fernando Rivadeneira, Douglas P Kiel, L Adrienne Cupples, Yi-Hsiang Hsu
Sexual dimorphism in various bone phenotypes, including bone mineral density (BMD), is widely observed; however, the extent to which genes explain these sex differences is unclear. To identify variants with different effects by sex, we examined gene-by-sex autosomal interactions genome-wide, and performed expression quantitative trait loci (eQTL) analysis and bioinformatics network analysis. We conducted an autosomal genome-wide meta-analysis of gene-by-sex interaction on lumbar spine (LS) and femoral neck (FN) BMD in 25,353 individuals from 8 cohorts...
October 2012: Journal of Bone and Mineral Research: the Official Journal of the American Society for Bone and Mineral Research
A Cecile Jw Janssens, John Pa Ioannidis, Cornelia M van Duijn, Julian Little, Muin J Khoury
The rapid and continuing progress in gene discovery for complex diseases is fueling interest in the potential application of genetic risk models for clinical and public health practice. The number of studies assessing the predictive ability is steadily increasing, but the quality and completeness of reporting varies. A multidisciplinary workshop sponsored by the Human Genome Epidemiology Network developed a checklist of 25 items recommended for strengthening the reporting of genetic risk prediction studies (the GRIPS statement), building on the principles established by prior reporting guidelines...
2011: Genome Medicine
Nikolaos A Patsopoulos, John Pa Ioannidis
BACKGROUND: Evidence for medical interventions sometimes derives from data that are no longer up to date. These data can influence the outcomes of meta-analyses, yet do not always reflect current clinical practice. We examined the age of the data used in meta-analyses contained within systematic reviews of medical interventions, and investigated whether authors consider the age of these data in their interpretations. METHODS: From Issue 4, 2005, of the Cochrane Database of Systematic Reviews we randomly selected 10% of systematic reviews containing at least 1 meta-analysis...
2009: Open Medicine: a Peer-reviewed, Independent, Open-access Journal
Alexandros Sotiriadis, George Makrydimas, Stefania Papatheodorou, John Pa Ioannidis
BACKGROUND: Infants born at term by elective caesarean delivery are more likely to develop respiratory morbidity than infants born vaginally. Prophylactic corticosteroids in singleton preterm pregnancies accelerate lung maturation and reduce the incidence of respiratory complications. OBJECTIVES: The objective of this review was to assess the effect of prophylactic corticosteroid administration before elective caesarean section at term, as compared to usual management without corticosteroids, in reducing neonatal respiratory morbidity and admission to special care with respiratory complications...
2009: Cochrane Database of Systematic Reviews
Nicholas C Stefanis, Thomas A Trikalinos, Dimitrios Avramopoulos, Nikos Smyrnis, Ioannis Evdokimidis, Evangelia E Ntzani, Alex Hatzimanolis, John Pa Ioannidis, Costas N Stefanis
BACKGROUND: While association studies on schizophrenia show conflicting results regarding the importance of the regulator of the G-protein signaling 4 (RGS4) gene, recent work suggests that RGS4 may impact on the structural and functional integrity of the prefrontal cortex. We aimed to study associations of common RGS4 variants with prefrontal dependent cognitive performance and schizotypy endophenotypes at the population level. METHODS: Four RGS4 single nucleotide polymorphisms (SNP1 [rs10917670], SNP4 [rs951436], SNP7 [rs951439], and SNP18 [rs2661319]) and their haplotypes were selected...
2008: Behavioral and Brain Functions: BBF
Despina G Contopoulos-Ioannidis, Ioanna Kouri, John Pa Ioannidis
The response to beta2-agonist treatment shows large repeatability within individuals and may thus be determined by genetic influences. Here we present a systematic overview of the available genetic association and linkage data for beta2-agonist treatment response. Systematic searches identified 66 eligible articles, as of March 2007, pertaining either to B2AR gene polymorphisms and short-acting or long-acting beta2-agonists or to another 29 different genes. We systematize these study results according to gene, agent and type of outcomes addressed...
August 2007: Pharmacogenomics
John PA Ioannidis
There is considerable evidence that the translation rate of major basic science promises to clinical applications has been inefficient and disappointing. The deficiencies of translational science have often been proposed as an explanation for this failure. An alternative explanation is that until recently basic science advances have made oversimplified assumptions that have not matched the true etiological complexity of most common diseases; while clinical science has suffered from poor research practices, overt biases and conflicts of interest...
January 31, 2004: Journal of Translational Medicine
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