G. Guyatt’s research while affiliated with McMaster University and other places

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Publications (148)


Estimating Prognosis Among Advanced Heart Failure Patients Referred for Advanced Heart Failure Therapies at the University Health Network
  • Article

April 2024

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9 Reads

The Journal of Heart and Lung Transplantation

T.A. Buchan

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M. Casciato

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R. Uxa

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Predicting 1-Year Mortality in Ambulatory Heart Failure Patients: Empiric Models Outperform Physician Intuitive Estimates

April 2022

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17 Reads

The Journal of Heart and Lung Transplantation

Purpose This multicenter Canadian prospective cohort study evaluated the accuracy of physician predictions in comparison to model predictions in estimating 1-year mortality in ambulatory patients with heart failure (HF). Methods We included consented consecutive ambulatory HF patients (left ventricular ejection fraction (LVEF) <40%) followed at 11 HF clinics in 5 provinces in Canada (2018-2020). In a closed-question survey, HF cardiologists and family doctors, using their clinical judgment, estimated patient 1-year mortality in absolute terms. We collected clinical information to describe the population and calculate predicted mortality using three predictive models: the Seattle HF Model (SHFM), the MAGGIC score and the HF Meta-score. We documented patients’ mortality over one year. Physicians were unaware of model predictions. We calculated mortality using Cox proportional hazards and assessed model and physician predictive accuracy using discrimination and calibration. Results We included 1,563 ambulatory HF patients, mean age of 63±14 years, 24% female, 70% NTHA class I-II, mean LVEF of 28±7%, and median brain natriuretic peptide of 350 pg/ml (25th-75th percentile 130-700). The population 1-year mortality was 7% (95%CI 6%-8%). Models’ discrimination (c-statistic 0.80 for MAGGIC and HF meta-score, 0.84 for SHFM) proved superior to physicians (0.77 for family doctors and 0.78 for HF cardiologists). Models’ calibration was adequate for patients at lower risk, but overestimated risk in those whose 1-year mortality was > 20%. In contrast, family doctors and HF cardiologists overestimated risk throughout the risk spectrum. In low-risk patients (1-year mortality ∼1%), physicians predicted a risk 7%-10%; in medium-risk patients (1-year mortality ∼5%), physicians predicted 15%-20%; and in high-risk patients (mortality >15%), physicians predicted >25%. Conclusion Predictive models showed higher accuracy in predicting 1-year mortality in ambulatory HF population than family doctors and HF cardiologists, both of whom consistently overestimated risk, potentially exposing patients early to more aggressive care. Incorporating predictive models in family and HF cardiology practices may improve patient management and resource use.


Extracorporeal Membrane Oxygenation for Early Graft Dysfunction Following Heart Transplantation: A Systematic Review and Meta-Analysis
  • Article
  • Full-text available

April 2021

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91 Reads

The Journal of Heart and Lung Transplantation

Purpose Early graft dysfunction (EGD) is a major cause of morbidity and mortality following heart transplantation (HT). Severe EGD often includes the use of veno-arterial extracorporeal membrane oxygenation (VA-ECMO). Studies evaluating its effectiveness are mostly single centre observations with variable outcomes. This systematic review and meta-analysis appraises the available evidence and evaluates prognosis in HT patients with EGD requiring VA-ECMO. Methods We conducted a systematic search of Ovid Medline, Embase and the Cochrane databases to 05/15/2020. Studies of adults who received VA-ECMO during their index hospitalization after HT and reported on mortality at any timepoint were included. We included observational studies published after 2009, in any language, as abstracts or full texts. Outcomes of interest were short-term mortality, 1-year mortality and VA-ECMO complications. We used QUIPS to assess risk of bias and GRADE to assess the quality of the evidence. Data was pooled using random-effects models. Results We included 50 studies of 1472 patients with 504 short-term mortality events. Most studies were retrospective (94%), single centre (88%), and at low/acceptable risk of bias overall (76%). Pooled short-term mortality was 33% (95%CI: 27-38%, I² =76%) and 1-year mortality was 46% (95%CI: 37-54%, I² =81%). Risk of bias, publication type, recruitment timeframe, and use of VA-ECMO for only primary graft dysfunction as per the ISHLT definition did not explain heterogeneity in subgroup analyses. Reported VA-ECMO complications were 38% (95%CI: 27-49%) for dialysis, 36% (95%CI: 26-47%) for bleeding, 22% (95%CI: 14-31%) for infection and 5% (95%CI: 1-10%) for limb ischemia. Conclusion One-third of HT patients with EGD supported with VA-ECMO are at risk of short-term death. An individual patient data meta-analysis is warranted to further understand the mortality risk and gain insight into risk factors associated with outcomes in this population.

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LO21: Consistency of CTAS scores by presenting complaint pre and post eCTAS implementation in 35 emergency departments across Ontario

May 2020

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16 Reads

Canadian Journal of Emergency Medicine

Introduction: eCTAS is a real time electronic triage decision-support tool designed to improve patient safety and quality of care by standardizing the application of the Canadian Triage and Acuity Scale (CTAS). The tool dynamically calculates a recommended CTAS score based on the presenting complaint, vital signs and selected clinical modifiers. The primary objective was to assess consistency of CTAS score distributions across 35 emergency departments (EDs) by 16 presenting complaints pre and post eCTAS implementation. Methods: This retrospective cohort study used population-based administrative data from January 2016 to December 2018 from all hospital EDs in Ontario that had implemented eCTAS with at least 9 months of data. Following a 3-month stabilization period, we compared data for 6 months post-eCTAS implementation to the same 6-month period the previous year (pre-implementation) to account for potential seasonal variation, patient volume and case-mix. We included triage encounters of adult (≥18 years) patients if they had one of 16 pre-specified high-volume, presenting complaints. A paired-samples t-test was used to determine consistency by estimating the absolute difference in CTAS distribution for each presenting complaint, by each hospital, pre and post eCTAS implementation, compared to the overall average of the 35 EDs. Results: There were 183,231 triage encounters in the pre-eCTAS cohort and 179,983 in the post-eCTAS cohort from 35 EDs across the province. Triage scores were more consistent with the overall average after eCTAS implementation in 6 (37.5%) presenting complaints: chest pain (cardiac features) (p < 0.001), extremity weakness/symptoms of cerebrovascular accident (p < 0.001), fever (p < 0.001), shortness of breath (p < 0.001), syncope (p = 0.02), and hyperglycemia (p = 0.03). Triage consistency was similar pre and post eCTAS implementation for the presenting complaints of altered level of consciousness, anxiety/situational crisis, confusion, depression/suicidal/deliberate self-harm, general weakness, head injury, palpitations, seizure, substance misuse/intoxication or vertigo. Conclusion: A standardized, electronic approach to performing triage assessments increased consistency in CTAS scores across many, but not all, high-volume CEDIS complaints. This does not reflect triage accuracy, as there are no known benchmarks for triage accuracy. Improvements in consistency were greatest for sentinel presenting complaints with a minimum allowable CTAS score.


Citations (50)


... Given that the median time to progression was 143 days, it seems reasonable that the initial interval scan should be performed within 6 months and be repeated after 12. Interestingly, progression was detected via surveillance CXR in 6 out of 27 patients who progressed. This highlights the importance of regular chest surveillance in STS patients, something which the SAFETY trial is currently investigating [19]. Gamboa et al. previously investigated surveillance methods in high-grade STS patients, comparing CT surveillance to CXR surveillance, finding no improvement in detection and intervention rates in the CT arm [20]. ...

Reference:

What Is the Significance of Indeterminate Pulmonary Nodules in High-Grade Soft Tissue Sarcomas? A Retrospective Cohort Study
The Surveillance after Extremity Tumor Surgery (SAFETY) trial: Protocol for a pilot study to determine the feasibility of a multi-centre randomised controlled trial

BMJ Open

... The first Committee to Advise on Tropical Medicine and Travel (CATMAT) statement, which was based on GRADE (Grading of Recommendations Assessment, Development, and Evaluation) methodology, concluded that the risk of acquiring typhoid in travellers to South Asia was about 1/3000 as compared with about 1/50 000 to 1/100 000 for destinations in North and Sub-Saharan Africa, the Middle East and South America and less than 1/300 000 among visitors to the Caribbean, Central America and the Eastern Mediterranean. 80,81 More recent publications essentially confirm the gradient and offer more details: In Australia, 887 cases of typhoid fever acquired abroad 2010 to 2017 were notified. When denominator data were applied, the IR was highest with 28.5 and 21.0/100 000 pm for Samoa (n = 34) and South Asia (n = 667), respectively. ...

CATMAT Statement on International Travellers and Typhoid - a welcome development
  • Citing Article
  • February 2014

Canada Communicable Disease Report

... The estimated RR was equal to 0.91 and with the statistical test, we concluded that there was no significant relationship between DAs and PSA screening. The study Riikonen et al showed that DAs don't affect the intention to perform the PSA test and the relationship between physician-patients should be strengthened and training must be face-to-face (36). ...

Decision aids for prostate cancer screening choice: A systematic review and meta-analysis
  • Citing Article
  • March 2018

European Urology Supplements

... In addition, long-term complications following less fatal VTE plague many patients, aggravating economic burden and lowering quality of life (18)(19)(20). However, as a major urologic surgery with high bleeding risk, willingness to use anticoagulant pharmacological prophylaxis exhibited large variation among urologists, often for fear of hemorrhage (21). It is thus critical to recognize patients with higher risk of VTE and take preventive measures to prevent its occurrence at an early stage following RC. ...

An international survey on the use of thromboprophylaxis in urological surgery
  • Citing Article
  • March 2018

European Urology Supplements

... 7 Aspirin is effective for prevention and treatment of venous and arterial thrombosis. [8][9][10] In outpatients with COVID-19, one large randomised trial suggested that colchicine might be effective for preventing disease progression. 11 Aspirin and oral anticoagulants have undergone randomised evaluation in outpatients with COVID-19 but the trials were stopped early owing to low event rates and provided no evidence of benefit. ...

Perioperative Aspirin for Prevention of Venous Thromboembolism: The PeriOperative ISchemia Evaluation-2 Trial and a Pooled Analysis of the Randomized Trials

Survey of Anesthesiology

... In line with recent calls by USP-STF and others to address racialized health inequities and the role of racism through clinical guidelines [60][61][62]90], key informants recommended that cervical cancer screening guidelines be formulated based on racially/ ethnically disaggregated data that meaningfully consider the specific historical, structural, social, and economic contexts of diverse racially minoritized groups and subgroups, including the impact of racism on health and health care [60][61][62][91][92][93][94]. Further, they suggested that the specific and unique lived experiences and social contexts of Black, Latine, Native, and Asian communities be centered when developing clinical guidelines in order to facilitate the delivery of equitable cervical cancer screening and follow-up care among diverse racially minoritized groups [55,95,96]. Finally, they noted that the process of formulating cervical cancer screening guidelines should be rigorously evaluated through a health equity lens and in partnership with racially minoritized communities [96]. ...

GRADE Equity guidelines 1: Health equity in guideline development- introduction and rationale

Journal of Clinical Epidemiology

... Several other studies have shown that dalteparin can be used safely in critically ill patients with renal insufficiency. 25,26 Ideally, we would like to have intradialytic anti-Xa levels to ensure adequate but also to rule out excessive anticoagulation. Due to practical reason, this is not possible for nocturnal home HD patients. ...

DALTEPARIN THROMBOPROPHYLAXIS IN CRITICALLY ILL PATIENTS WITH SEVERE RENAL INSUFFICIENCY: THE DIRECT STUDY
  • Citing Article
  • July 2007

Journal of Thrombosis and Haemostasis

... Notably, the analysis of the ED discharge results suggests that, comparatively, old RBC transfusion was not harmful, and it might be associated with a better clinical outcome. Furthermore, although specific studies did not show significant differences, these RCTs showed a trend toward favorable outcomes; 13,16 this was consistent with a previous meta-analysis 37 . To date, most studies have focused primarily on whether old RBCs are less harmful than fresh RBCs. ...

Mortality outcomes in patients transfused with fresher versus older red blood cells: A meta-analysis
  • Citing Article
  • February 2017

Vox Sanguinis

... Given the observational and registry based study design we could not eliminate selection bias and residual confounding; however, multivariable regression modeling was conducted to adjust for measured confounders. 20 Additional variables that may be associated with OAC and outcomes including socioeconomic status and health literacy were not collected and limit the generalizability of results. Since LVEF was not collected, HF patients were not sub-categorized by preserved or reduced ejection fraction. ...

Harm (observational studies)
  • Citing Article
  • January 2008

... Importantly, contentious dialogues do not come from within the ranks of EBM nor of NM. EBM advocates espouse incorporation of patient values and preferences into evidence-based decision making [14], while leading developers of NM have called for its integration with appropriate attention to for scientific criteria and evidence151617.Already proposed, a marriage of NM and EBM only awaits the development of a conceptual framework capable of accommodating their integration for its consummation [18,19]. The purpose of this exposition is to elaborate the essential features of a model of clinical practice that integrates the agendas of EBM and of NM and to begin to explore its practical implications and utility. ...

Decision making and the patient
  • Citing Article
  • January 2008