Gordon H Guyatt

McMaster University, Hamilton, Ontario, Canada

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Publications (886)6924.25 Total impact

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    ABSTRACT: Whether the minimal important difference (MID) is best framed using an absolute change or a relative change in score when interpreting patient-reported outcomes remains uncertain.
    Journal of Clinical Epidemiology 03/2015; DOI:10.1016/j.jclinepi.2015.02.017 · 5.48 Impact Factor
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    ABSTRACT: Dental practitioners spend most of their time administering treatments. To ensure that their clinical decisions are informed by the best available evidence, dental practitioners need to be skilled in critically appraising studies addressing therapy issues. Randomized controlled trials offer the optimal study design to inform decisions regarding therapy. The critical appraisal of randomized controlled trials involves assessing the risk of bias, results, and applicability. In this article, the authors present these concepts and provide guidance for this type of appraisal. Dentists who wish to inform their clinical decisions regarding therapy and prevention questions can use these guidelines to decide what type of studies to search, define the specific question of interest to search efficiently for these studies, and critically appraise an article about therapy or prevention. Copyright © 2015 American Dental Association. Published by Elsevier Inc. All rights reserved.
    Journal of the American Dental Association (1939) 03/2015; 146(1):42-49.e1. DOI:10.1016/j.adaj.2014.11.010 · 1.82 Impact Factor
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    ABSTRACT: Patients who are diagnosed with localized prostate cancer need to make critical treatment decisions that are sensitive to their values and preferences. The role of decision aids in facilitating these decisions is unknown. The authors conducted a systematic review of randomized trials of decision aids for localized prostate cancer. Teams of 2 reviewers independently identified, selected, and abstracted data from 14 eligible trials (n = 3377 men), of which 10 were conducted in North America. Of these, 11 trials compared decision aids with usual care, and 3 trials compared decision aids with other decision aids. Two trials suggested a modest positive impact on decisional regret. Results across studies varied widely for decisional conflict (4 studies), satisfaction with decision (2 studies), and knowledge (2 studies). No impact on treatment choices was observed (6 studies). In conclusion, scant evidence at high risk of bias suggests the variable impact of existing decision aids on a limited set of decisional processes and outcomes. Because current decision aids provide information but do not directly facilitate shared decision making, subsequent efforts would benefit from user-centered design of decision aids that promote shared decision making. CA Cancer J Clin 2015. © 2015 American Cancer Society. © 2015 American Cancer Society.
    CA A Cancer Journal for Clinicians 03/2015; DOI:10.3322/caac.21272 · 153.46 Impact Factor
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    ABSTRACT: Open tibial shaft fractures are one of the most devastating orthopaedic injuries. Surgical treatment options include reamed or unreamed nailing, plating, Ender nails, Ilizarov fixation, and external fixation. Using a network meta-analysis allows comparison and facilitates pooling of a diverse population of randomized trials across these approaches in ways that a traditional meta-analysis does not. Our aim was to perform a network meta-analysis using evidence from randomized trials on the relative effect of alternative approaches on the risk of unplanned reoperation after open fractures of the tibial diaphysis. Our secondary study endpoints included malunion, deep infection, and superficial infection. A network meta-analysis allows for simultaneous consideration of the relative effectiveness of multiple treatment alternatives. To do this on the subject of surgical treatments for open tibial fractures, we began with systematic searches of databases (including EMBASE and MEDLINE) and performed hand searches of orthopaedic journals, bibliographies, abstracts from orthopaedic conferences, and orthopaedic textbooks, for all relevant material published between 1980 and 2013. Two authors independently screened abstracts and manuscripts and extracted the data, three evaluated the risk of bias in individual studies, and two applied Grading of Recommendation Assessment, Development and Evaluation (GRADE) criteria to bodies of evidence. We included all randomized and quasirandomized trials comparing two (or more) surgical treatment options for open tibial shaft fractures in predominantly (ie, > 80%) adult patients. We calculated pooled estimates for all direct comparisons and conducted a network meta-analysis combining direct and indirect evidence for all 15 comparisons between six stabilization strategies. Fourteen trials published between 1989 and November 2011 met our inclusion criteria; the trials comprised a total of 1279 patients surgically treated for open tibial shaft fractures. Moderate confidence evidence showed that unreamed nailing may reduce the likelihood of reoperation compared with external fixation (network odds ratio [OR], 0.38; 95% CI, 0.23-0.62; p < 0.05), although not necessarily compared with reamed nailing (direct OR, 0.74; 95% CI, 0.45-1.24; p = 0.25). Only low- or very low-quality evidence informed the primary outcome for other treatment comparisons, such as those involving internal plate fixation, Ilizarov external fixation, and Ender nailing. Method ranking based on reoperation data showed that unreamed nailing had the highest probability of being the best treatment, followed by reamed nailing, external fixation, and plate fixation. CIs around pooled estimates of malunion and infection risk were very wide, and therefore no conclusive results could be made based on these data. Current evidence suggests that intramedullary nailing may be superior to other fixation strategies for open tibial shaft fractures. Use of unreamed nails over reamed nails also may be advantageous in the setting of open fractures, but this remains to be confirmed. Unfortunately, these conclusions are based on trials that have had high risk of bias and poor precision. Larger and higher-quality head-to-head randomized controlled trials are required to confirm these conclusions and better inform clinical decision-making. Level I, therapeutic study.
    Clinical Orthopaedics and Related Research 02/2015; DOI:10.1007/s11999-015-4224-y · 2.79 Impact Factor
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    ABSTRACT: Decision aids can help shared decision making, but most have been hard to produce, onerous to update, and are not being used widely. Thomas Agoritsas and colleagues explore why and describe a new electronic model that holds promise of being more useful for clinicians and patients to use together at the point of care.
    BMJ (online) 02/2015; 350(feb10 14):g7624. DOI:10.1136/bmj.g7624 · 16.38 Impact Factor
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    ABSTRACT: Questions regarding harm are common in dental practice. Observational, nonrandomized studies (that is, cohort studies and case-control studies) are the designs used by investigators to answer most of these questions. A critical appraisal of these studies should include an assessment of the risk of bias, the results, and the applicability of the study. The authors provide the concepts and guidelines that dentists can apply to most effectively use articles regarding harm to guide their clinical practice. Dentists who wish to inform their clinical decisions regarding questions of harm can use these guidelines to decide what type of studies to search, define the specific question of interest to search efficiently for these studies, and critically appraise an article about harm. Copyright © 2015 American Dental Association. Published by Elsevier Inc. All rights reserved.
    Journal of the American Dental Association (1939) 02/2015; 146(2):94-101.e1. DOI:10.1016/j.adaj.2014.12.002 · 1.82 Impact Factor
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    ABSTRACT: The objective of the study was to assess the association between Grading of Recommendations Assessment, Development and Evaluation (GRADE) factors and the strength of recommendations. The study was conducted as part of the development of clinical practice guideline (CPG) by American Association of Blood Banking related to role of prophylactic vs. therapeutic transfusion for the management of thrombocytopenia. The association between GRADE factors and strength of recommendations was assessed using logistic regression and multilevel mixed effect logistic regression model. Seventeen members of the CPG panel participated in the recommendation process. The quality of evidence was the only statistically significant (odds ratio = 4.5; P < 0.001) GRADE factor associated with the strength of recommendations. The predictive model showed that there is about 90% probability that panelists would issue the same (strong) recommendation when confidence in the effects of intervention is high vs. 10% when the quality of evidence is very low. The results showed that quality of evidence is a key determinant for making a strong vs. a weak recommendation. Copyright © 2015 Elsevier Inc. All rights reserved.
    Journal of Clinical Epidemiology 02/2015; DOI:10.1016/j.jclinepi.2014.12.015 · 5.48 Impact Factor
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    ABSTRACT: Decision aids can help shared decision making, but most have been hard to produce, onerous to update, and are not being used widely. Thomas Agoritsas and colleagues explore why and describe a new electronic model that holds promise of being more useful for clinicians and patients to use together at the point of care.
    BMJ Clinical Research 01/2015; 350:g7624. · 14.09 Impact Factor
  • Journal of Clinical Epidemiology 12/2014; DOI:10.1016/j.jclinepi.2014.12.011 · 5.48 Impact Factor
  • Polskie archiwum medycyny wewnȩtrznej 12/2014; 124(12):659-60. · 2.05 Impact Factor
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    ABSTRACT: Pharmacological thromboprophylaxis in the peri-operative period involves a trade-off between reduction in venous thromboembolism (VTE) and an increase in bleeding. Baseline risks, in the absence of prophylaxis, for VTE and bleeding are known to vary widely between urological procedures, but their magnitude is highly uncertain. Systematic reviews and meta-analyses addressing baseline risks are uncommon, needed, and require methodological innovation. In this article, we describe the rationale and methods for a series of systematic reviews of the risks of symptomatic VTE and bleeding requiring reoperation in urological surgery.Methods/design: We searched MEDLINE from January 1, 2000 until April 10, 2014 for observational studies reporting on symptomatic VTE or bleeding after urological procedures. Additional studies known to experts and studies cited in relevant review articles were added. Teams of two reviewers, independently assessed articles for eligibility, evaluated risk of bias, and abstracted data. We derived best estimates of risk from the median estimates among studies rated at the lowest risk of bias. The primary endpoints were 30-day post-operative risk estimates of symptomatic VTE and bleeding requiring reoperation, stratified by procedure and patient risk factors. This series of systematic reviews will inform clinicians and patients regarding the trade-off between VTE prevention and bleeding. Our work advances standards in systematic reviews of surgical complications, including assessment of risk of bias, criteria for arriving at best estimates of risk (including modeling of timing of events and dealing with suboptimal data reporting), dealing with subgroups at higher and lower risk of bias, and use of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to rate certainty in estimates of risk. The results will be incorporated in the upcoming European Association Urology Guideline on Thromboprophylaxis.Systematic review registration: PROSPERO CRD42014010342.
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    ABSTRACT: In 2007 the World Health Organization (WHO) adopted the GRADE system for development of public health guidelines. Previously we found that many strong recommendations issued by WHO are based on evidence for which there is only low or very low confidence in the estimates of effect (discordant recommendations). GRADE guidance indicates that such discordant recommendations are rarely appropriate but suggests five paradigmatic situations in which discordant recommendations may be warranted.
    Journal of Clinical Epidemiology 12/2014; DOI:10.1016/j.jclinepi.2014.10.011 · 5.48 Impact Factor
  • R. Jaeschke, G. H. Guyatt, H. Schünemann
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    ABSTRACT: Whenever somebody, particular any one in authority, provides guidance to somebody else, a recommendation is born. Similarly, when an authoritative group issues a number of recommendations at one time, healthcare providers are presented with new Clinical Practice Guidelines (CPGs). CPGs are defined today by World Health Organization as “recommendations intended to assist providers and recipients of health care and other stakeholders to make informed decisions” have been with us from the beginning of medicine. If you were to read a 30-year-old medical textbook, you would see, in essence, a description of facts accompanied by a multitude of recommendations. Although it cannot be said that these textbooks are CPGs, they do provide the essential function of CPGs.The clinician of today is confronted with multiple documents entitled CPGs. In this context, the editors of Intensive Care Medicine asked us to prepare an editorial addressing choice of the best guidelines. Considering this we find ...
    Intensive Care Medicine 12/2014; DOI:10.1007/s00134-014-3609-9 · 5.54 Impact Factor
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    ABSTRACT: Knowing how to search for evidence that can inform clinical decisions is a fundamental skill for the practice of evidence-based dentistry. There are many available types of evidence-based resources, characterized by their degrees of coverage of preappraised or summarized evidence at varying levels of processing, from primary studies to systematic reviews and clinical guidelines. The practice of evidence-based dentistry requires familiarity with these resources. In this article, the authors describe the process of searching for evidence: defining the question, identifying the question's nature and main components, and selecting the study design that best addresses the question. Dentists who wish to inform their decisions with the current best evidence can use these guidelines to define their questions of interest and search efficiently for this evidence.
    Journal of the American Dental Association (1939) 12/2014; 145(12):1262-7. DOI:10.14219/jada.2014.113 · 1.82 Impact Factor
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    ABSTRACT: Although multivessel coronary artery disease has been associated with poor health outcomes in patients with acute ST-segment elevation myocardial infarction (STEMI), the optimal approach to revascularization remains uncertain. The objective of this review was to determine the benefits and harms of culprit vessel only vs immediate complete percutaneous coronary intervention (PCI) in patients with acute STEMI. We searched MEDLINE, EMBASE, the Cochrane Register of Controlled Trials, and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) for randomized controlled trials (RCTs). Teams of 2 reviewers, independently and in duplicate, screened titles and abstracts, completed full-text reviews, and abstracted data. We calculated pooled risk ratios (RRs) and associated 95% confidence intervals (CIs) using random-effect models for nonfatal myocardial infarction (MI), revascularization, cardiovascular mortality, all-cause mortality, and adverse events, and used the GRADE approach to rate confidence in estimates of effect. Of 341 patients randomized to complete revascularization and followed to study conclusion, 31 experienced revascularization, as did 80 of 324 randomized to culprit vessel only revascularization (RR: 0.35, 95% CI: 0.24-0.53). Ten patients in the complete revascularization group and 28 patients in the culprit vessel only revascularization group experienced nonfatal MI (RR: 0.35, 95% CI: 0.17-0.72). All-cause mortality and cardiac deaths did not differ between groups (RR: 0.69, 95% CI: 0.40-1.21 for all-cause mortality; RR: 0.48, 95% CI: 0.22-1.04 for cardiac deaths). Pooled data from 3 RCTs suggest that immediate complete revascularization probably reduces revascularization in patients with acute STEMI; although results suggest possible benefits on MI and death, confidence in estimates is low.
    Clinical Cardiology 12/2014; 37(12). DOI:10.1002/clc.22333 · 2.23 Impact Factor
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    Jason W. Busse, Gordon H. Guyatt
    Journal of Clinical Epidemiology 11/2014; DOI:10.1016/j.jclinepi.2014.11.012 · 5.48 Impact Factor
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    ABSTRACT: Introduction: Chronic neuropathic pain is associated with reduced health-related quality of life and substantial socioeconomic costs. Current research addressing management of chronic neuropathic pain is limited. No review has evaluated all interventional studies for chronic neuropathic pain, which limits attempts to make inferences regarding the relative effectiveness of treatments. Methods and analysis: We will conduct a systematic review of all randomised controlled trials evaluating therapies for chronic neuropathic pain. We will identify eligible trials, in any language, by a systematic search of CINAHL, EMBASE, MEDLINE, AMED, HealthSTAR, DARE, PsychINFO and the Cochrane Central Registry of Controlled Trials. Eligible trials will be: (1) enrol patients presenting with chronic neuropathic pain, and (2) randomise patients to alternative interventions (pharmacological or non-pharmacological) or an intervention and a control arm. Pairs of reviewers will, independently and in duplicate, screen titles and abstracts of identified citations, review the full texts of potentially eligible trials and extract information from eligible trials. We will use a modified Cochrane instrument to evaluate risk of bias of eligible studies, recommendations from the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) to inform the outcomes we will collect, and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system to evaluate our confidence in treatment effects. When possible, we will conduct: (1) in direct comparisons, a random-effects meta-analysis to establish the effect of reported therapies on patient-important outcomes; and (2) a multiple treatment comparison meta-analysis within a Bayesian framework to assess the relative effects of treatments. We will define a priori hypotheses to explain heterogeneity between studies, and conduct meta-regression and subgroup analyses consistent with the current best practices. Ethics and Dissemination: We do not require ethics approval for our proposed review. We will disseminate our findings through peer-reviewed publications and conference presentations.
    BMJ Open 11/2014; 4:e006112. DOI:10.1136/bmjopen-2014-006112 · 2.06 Impact Factor
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    ABSTRACT: In the last decade, major advances in venous thromboembolism (VTE) prophylaxis in orthopaedic surgery have included the development of new anticoagulants that are poised to replace low molecular weight heparins (LMWHs) and improvements in operative and perioperative care that have likely led to a decline in the rates of symptomatic VTE and mortality independent of anticoagulant use. A systematic review of the literature was performed to identify phase III randomized controlled trials of VTE prevention that compared new anticoagulants (fondaparinux, rivaroxaban, dabigatran, apixaban) with LMWH (enoxaparin) in major elective orthopaedic surgery. Our aims were to obtain best estimates of the rates of patient important events (symptomatic VTE, mortality, and bleeding) in contemporary trials of VTE prevention, and to consider the implications of these contemporary rates for clinical practice and future research. Fourteen studies, which enrolled 40,285 patients, were included in the analyses. The combined median rates (ranges) for all five anticoagulants for symptomatic VTE and mortality to the end of follow-up were 0.99 % (0.15-2.58 %) and 0.26 % (0-0.92 %) respectively, whereas the median rate (range) of clinically important bleeding was 3.44 % (2.25-7.74 %). In contemporary trials of anticoagulants, the rates of symptomatic VTE and mortality are low, but the rates of clinically important post-operative bleeding remain relatively high. Based on these results, we propose that approaches that minimize bleeding without substantially reducing efficacy merit investigation, particularly if improvement in surgical and perioperative care have also resulted in falling baseline patient important VTE rates independent of anticoagulant use.
    Journal of Thrombosis and Thrombolysis 11/2014; · 1.99 Impact Factor
  • Journal of the American Dental Association (1939) 11/2014; 145(11):1105-7. DOI:10.14219/jada.2014.102 · 1.82 Impact Factor

Publication Stats

62k Citations
6,924.25 Total Impact Points


  • 1984–2015
    • McMaster University
      • • Department of Clinical Epidemiology and Biostatistics
      • • Health Sciences Centre
      • • Department of Medicine
      • • Department of Family Medicine
      Hamilton, Ontario, Canada
  • 2010–2013
    • Princess Alexandra Hospital (Queensland Health)
      • Department of Internal Medicine and Clinical Epidemiology
      Brisbane, Queensland, Australia
  • 2012
    • Universitätsspital Basel
      • Institute for Clinical Epidemiology and Biostatistics (CEB)
      Bâle, Basel-City, Switzerland
    • University at Buffalo, The State University of New York
      • Department of Medicine
      Buffalo, NY, United States
    • SickKids
      Toronto, Ontario, Canada
  • 2009–2012
    • Institute for Work and Health
      Toronto, Ontario, Canada
    • University of British Columbia - Vancouver
      • Department of Medicine
      Vancouver, British Columbia, Canada
  • 2001–2012
    • Mayo Clinic - Rochester
      • Department of Internal Medicine
      Rochester, Minnesota, United States
    • Dalhousie University
      • Department of Medicine
      Halifax, Nova Scotia, Canada
  • 2008–2009
    • The University of Western Ontario
      • Department of Surgery
      London, Ontario, Canada
    • University of Tuebingen
      Tübingen, Baden-Württemberg, Germany
  • 2004–2009
    • London Health Sciences Centre
      • • Department of Surgery
      • • Division of Critical Care
      London, Ontario, Canada
  • 2007–2008
    • West Park Healthcare Centre
      Toronto, Ontario, Canada
  • 1996–2007
    • University of Toronto
      • • Department of Rehabilitation Science
      • • Department of Medicine
      Toronto, Ontario, Canada
    • Institute for Clinical Evaluative Sciences
      Toronto, Ontario, Canada
  • 2006
    • Nagoya City University
      • Department of Psychiatry and Cognitive-Behavioral Medicine
      Nagoya, Aichi, Japan
    • The Ottawa Hospital
      • Department of Medicine
      Ottawa, Ontario, Canada
  • 1995–2006
    • Hospital de la Santa Creu i Sant Pau
      Barcino, Catalonia, Spain
    • Johns Hopkins University
      Baltimore, Maryland, United States
    • University of Wisconsin - Milwaukee
      Milwaukee, Wisconsin, United States
  • 1994–2006
    • University of Ottawa
      • Institute of Population Health
      Ottawa, Ontario, Canada
  • 2005
    • Boston University
      • Division of Orthopaedic Surgery
      Boston, Massachusetts, United States
    • Iberoamerican Cochrane Centre
      Barcino, Catalonia, Spain
    • The Canadian College of Naturopathic Medicine
      Toronto, Ontario, Canada
  • 2003
    • University of Illinois at Chicago
      Chicago, Illinois, United States
    • University of Santiago, Chile
      CiudadSantiago, Santiago Metropolitan, Chile
    • Queen's University
      • Division of Rheumatology
      Kingston, Ontario, Canada
  • 2001–2003
    • Hamilton Health Sciences
      Hamilton, Ontario, Canada
  • 2002
    • Ruhr-Universität Bochum
      Bochum, North Rhine-Westphalia, Germany
    • Mayo Foundation for Medical Education and Research
      • Department of Medicine
      Scottsdale, AZ, United States
  • 1999–2002
    • Institut Universitaire de Cardiologie et de Pneumologie de Québec (Hôpital Laval)
      Québec, Quebec, Canada
    • University of Sydney
      Sydney, New South Wales, Australia
  • 1999–2001
    • The University of Calgary
      • Department of Medicine
      Calgary, Alberta, Canada
  • 2000
    • Indiana University-Purdue University Indianapolis
      • Department of Emergency Medicine
      Indianapolis, Indiana, United States
    • Mount Sinai Hospital
      New York City, New York, United States
    • Mount Sinai Medical Center
      New York, New York, United States
  • 1998–1999
    • Harvard Medical School
      • Department of Pediatrics
      Boston, MA, United States
    • The University of Tampa
      Tampa, Florida, United States
  • 1991–1997
    • St. Joseph's Healthcare Hamilton
      Hamilton, Ontario, Canada