Gordon H Guyatt

McMaster University, Hamilton, Ontario, Canada

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Publications (900)7117.52 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Pain is a patient-important outcome, but current reporting in randomized controlled trials and systematic reviews is often suboptimal, impeding clinical interpretation and decision making. A working group at the 2014 Outcome Measures in Rheumatology (OMERACT 12) was convened to provide guidance for reporting treatment effects regarding pain for individual studies and systematic reviews. For individual trials, authors should report, in addition to mean change, the proportion of patients achieving 1 or more thresholds of improvement from baseline pain (e.g., ≥ 20%, ≥ 30%, ≥ 50%), achievement of a desirable pain state (e.g., no worse than mild pain), and/or a combination of change and state. Effects on pain should be accompanied by other patient-important outcomes to facilitate interpretation. When pooling data for metaanalysis, authors should consider converting all continuous measures for pain to a 100 mm visual analog scale (VAS) for pain and use the established, minimally important difference (MID) of 10 mm, and the conventionally used, appreciably important differences of 20 mm, 30 mm, and 50 mm, to facilitate interpretation. Effects ≤ 0.5 units suggest a small or very small effect. To further increase interpretability, the pooled estimate on the VAS should also be transformed to a binary outcome and expressed as a relative risk and risk difference. This transformation can be achieved by calculating the probability of experiencing a treatment effect greater than the MID and the thresholds for appreciably important differences in pain reduction in the control and intervention groups. Presentation of relative effects regarding pain will facilitate interpretation of treatment effects.
    The Journal of Rheumatology 05/2015; DOI:10.3899/jrheum.141440 · 3.17 Impact Factor
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    ABSTRACT: Objective. Pain is a patient-important outcome, but current reporting in randomized controlled trials and systematic reviews is often suboptimal, impeding clinical interpretation and decision making. Methods. A working group at the 2014 Outcome Measures in Rheumatology (OMERACT 12) was convened to provide guidance for reporting treatment effects regarding pain for individual studies and systematic reviews. Results. For individual trials, authors should report, in addition to mean change, the proportion of patients achieving 1 or more thresholds of improvement from baseline pain (e.g., ≥ 20%, ≥ 30%, ≥ 50%), achievement of a desirable pain state (e.g., no worse than mild pain), and/or a combination of change and state. Effects on pain should be accompanied by other patient-important outcomes to facilitate interpretation. When pooling data for metaanalysis, authors should consider converting all continuous measures for pain to a 100 mm visual analog scale (VAS) for pain and use the established, minimally important difference (MID) of 10 mm, and the conventionally used, appreciably important differences of 20 mm, 30 mm, and 50 mm, to facilitate interpretation. Effects ≤ 0.5 units suggest a small or very small effect. To further increase interpretability, the pooled estimate on the VAS should also be transformed to a binary outcome and expressed as a relative risk and risk difference. This transformation can be achieved by calculating the probability of experiencing a treatment effect greater than the MID and the thresholds for appreciably important differences in pain reduction in the control and intervention groups. Conclusion. Presentation of relative effects regarding pain will facilitate interpretation of treatment effects. (J Rheumatol First Release May 15 2015; doi:10.3899/jrheum.141440) Key Indexing Terms: OMERACT OUTCOMES PAIN CLINICAL TRIALS VISUAL ANALOG SCALE SYSTEMATIC REVIEWS
    The Journal of Rheumatology 05/2015; DOI:10.3899/jrheum.141440) · 3.17 Impact Factor
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    ABSTRACT: To conduct a systematic review and meta-analysis to evaluate the effectiveness of hypnosis/relaxation therapy compared to no/minimal treatment in patients with temporomandibular disorders (TMD). Studies reviewed included randomized controlled trials (RCTs) where investigators randomized patients with TMD or an equivalent condition to an intervention arm receiving hypnosis, relaxation training, or hyporelaxation therapy, and a control group receiving no/minimal treatment. The systematic search was conducted without language restrictions, in Medline, EMBASE, CENTRAL, and PsycINFO, from inception to June 30, 2014. Studies were pooled using weighted mean differences and pooled risk ratios (RRs) for continuous outcomes and dichotomous outcomes, respectively, and their associated 95% confidence intervals (CI). Of 3,098 identified citations, 3 studies including 159 patients proved eligible, although none of these described their method of randomization. The results suggested limited or no benefit of hypnosis/relaxation therapy on pain (risk difference in important pain -0.06; 95% CI: -0.18 to 0.05; P = .28), or on pressure pain thresholds on the skin surface over the temporomandibular joint (TMJ) and masticatory muscles. Low-quality evidence suggested some benefit of hypnosis/relaxation therapy on maximal pain (mean difference on 100-mm scale = -28.33; 95% CI: -44.67 to -11.99; P =.007) and active maximal mouth opening (mean difference on 100-mm scale = -2.63 mm; 95% CI: -3.30 mm to -1.96 mm; P < .001) compared to no/minimal treatment. Three RCTs were eligible for the systematic review, but they were with high risk of bias and provided low-quality evidence, suggesting that hypnosis/relaxation therapy may have a beneficial effect on maximal pain and active maximal mouth opening but not on pain and pressure pain threshold. Larger RCTs with low risk of bias are required to confirm or refute these findings and to inform other important patient outcomes.
    05/2015; 29(2):115-125. DOI:10.11607/ofph.1330
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    ABSTRACT: Clinical practice guidelines represent highly processed evidence with associated recommendations to inform clinical practice and optimize patient care. Appropriately developed, evidence-based recommendations will integrate the best evidence regarding benefits and harms, the certainty of the evidence, patients' values and preferences, and resource utilization. The authors provide a structure for clinicians to critically appraise clinical practice guidelines to determine whether the guidelines offer trustworthy recommendations. Copyright © 2015 American Dental Association. Published by Elsevier Inc. All rights reserved.
    Journal of the American Dental Association (1939) 05/2015; 146(5):327-336.e1. DOI:10.1016/j.adaj.2015.03.015 · 2.24 Impact Factor
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    Journal of Clinical Epidemiology 04/2015; 68(4). DOI:10.1016/j.jclinepi.2015.02.001 · 5.48 Impact Factor
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    ABSTRACT: Fluid resuscitation, along with the early administration of antibiotics, is the cornerstone of treatment for patients with sepsis. However, whether differences in resuscitation fluids impact on the requirements for renal replacement therapy (RRT) remains unclear. To examine this issue, we performed a network meta-analysis (NMA), including direct and indirect comparisons, that addressed the effect of different resuscitation fluids on the use of RRT in patients with sepsis. The data sources MEDLINE, EMBASE, ACPJC, CINAHL and Cochrane Central Register were searched up to March 2014. Eligible studies included randomized trials reported in any language that enrolled adult patients with sepsis or septic shock and addressed the use of RRT associated with alternative resuscitation fluids. The risk of bias for individual studies and the overall certainty of the evidence were assessed. Ten studies (6664 patients) that included a total of nine direct comparisons were assessed. NMA at the four-node level showed that an increased risk of receiving RRT was associated with fluid resuscitation with starch versus crystalloid [odds ratio (OR) 1.39, 95 % credibility interval (CrI) 1.17-1.66, high certainty]. The data suggested no difference between fluid resuscitation with albumin and crystalloid (OR 1.04, 95 % CrI 0.78-1.38, moderate certainty) or starch (OR 0.74, 95 % CrI 0.53-1.04, low certainty). NMA at the six-node level showed a decreased risk of receiving RRT with balanced crystalloid compared to heavy starch (OR 0.50, 95 % CrI 0.34-0.74, moderate certainty) or light starch (OR 0.70, 95 % CrI 0.49-0.99, high certainty). There was no significant difference between balanced crystalloid and saline (OR 0.85, 95 % CrI 0.56-1.30, low certainty) or albumin (OR 0.82, 95 % CrI 0.49-1.37, low certainty). Of note, these trials vary in terms of case mix, fluids evaluated, duration of fluid exposure and risk of bias. Imprecise estimates contributed to low confidence in most estimates of effect. Among the patients with sepsis, fluid resuscitation with crystalloids compared to starch resulted in reduced use of RRT; the same may be true for albumin versus starch.
    European Journal of Intensive Care Medicine 04/2015; DOI:10.1007/s00134-015-3794-1 · 5.54 Impact Factor
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    ABSTRACT: Dental practitioners face new clinical challenges on a daily basis. New treatment options and diagnostic tools are disseminated quickly, and the volume of articles and new evidence is overwhelming. Systematic reviews summarize and synthesize the available evidence related to diagnosis, therapy, prognosis, and harm for clinicians, patients, and decision makers. Such reviews represent one of the most powerful tools to translate knowledge into action. The critical appraisal of this type of study involves assessing the risk of bias, results, and applicability of such study. The authors provide guidance for clinicians to critically appraise systematic reviews and apply the findings in clinical practice. Copyright © 2015 American Dental Association. Published by Elsevier Inc. All rights reserved.
    Journal of the American Dental Association (1939) 04/2015; 146(4):255-265.e1. DOI:10.1016/j.adaj.2015.01.025 · 2.24 Impact Factor
  • Yuqing Zhang, Yuan Zhang, Gordon H. Guyatt
    Complementary Therapies in Medicine 04/2015; DOI:10.1016/j.ctim.2015.03.012 · 2.22 Impact Factor
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    ABSTRACT: Using studies that established minimal important difference (MID) using anchor-based methods, we set out to address the relative merits of absolute and relative changes in establishing an instrument's MID. In seven data sets, we calculated correlations between global change ratings and absolute and relative score changes and conducted meta-analyses. We considered that the measure with the higher correlation represented the more valid approach. The meta-analyses showed no significant difference between pooled correlations of absolute and relative difference on health-related quality of life instrument with global transition scores of symptoms, emotional function, physical function, and cognitive function. In four of five domains, there was at least one study in which the absolute was significantly superior to the relative; in one of these four, one study showed statistically significant superior performance of the relative. In an analysis restricted to patients with low baseline scores for the domain of cognitive function, the relative approach showed higher correlation with global rating than did the absolute approach. Although we found no consistent superiority of either approach to establishing the MID, when differences existed they usually favored the absolute, which also has advantages of simplicity and ease of pooling across studies. Researchers may consider the absolute as a default but also compare both methods on an instrument by instrument basis. Copyright © 2015 Elsevier Inc. All rights reserved.
    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 · 2.24 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; 65(3). DOI:10.3322/caac.21272 · 162.50 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 · 2.88 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 · 2.24 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; 68(5). 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.
    12/2014; 3(1):150. DOI:10.1186/2046-4053-3-150
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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

Publication Stats

63k Citations
7,117.52 Total Impact Points

Institutions

  • 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
    • Institute for Work and Health
      Toronto, Ontario, Canada
    • University at Buffalo, The State University of New York
      • Department of Medicine
      Buffalo, NY, United States
    • SickKids
      Toronto, Ontario, 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
    • Hamilton College
      Клинтон, New York, United States
  • 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
    • University of Groningen
      Groningen, Groningen, Netherlands
    • The Ottawa Hospital
      • Department of Medicine
      Ottawa, Ontario, Canada
    • Nagoya City University
      • Department of Psychiatry and Cognitive-Behavioral Medicine
      Nagoya, Aichi, Japan
  • 1995–2006
    • Hospital de la Santa Creu i Sant Pau
      Barcino, Catalonia, Spain
    • University of Wisconsin - Milwaukee
      Milwaukee, Wisconsin, United States
  • 1994–2006
    • University of Ottawa
      • Institute of Population Health
      Ottawa, Ontario, Canada
  • 2005
    • Iberoamerican Cochrane Centre
      Barcino, Catalonia, Spain
    • Boston University
      • Division of Orthopaedic Surgery
      Boston, Massachusetts, United States
    • The Canadian College of Naturopathic Medicine
      Toronto, Ontario, Canada
  • 2003
    • Queen's University
      • Division of Rheumatology
      Kingston, Ontario, Canada
    • University of Illinois at Chicago
      Chicago, Illinois, United States
    • University of Santiago, Chile
      CiudadSantiago, Santiago Metropolitan, Chile
  • 2001–2003
    • Hamilton Health Sciences
      Hamilton, Ontario, Canada
  • 2002
    • Mayo Foundation for Medical Education and Research
      • Department of Medicine
      Scottsdale, AZ, United States
    • Ruhr-Universität Bochum
      Bochum, North Rhine-Westphalia, Germany
  • 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
  • 1995–2001
    • Johns Hopkins University
      • Department of Anesthesiology and Critical Care Medicine
      Baltimore, MD, United States
  • 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