Gordon H. Guyatt

Bio: Gordon H. Guyatt is an academic researcher from McMaster University. The author has contributed to research in topics: Randomized controlled trial & Evidence-based medicine. The author has an hindex of 231, co-authored 1620 publications receiving 228631 citations. Previous affiliations of Gordon H. Guyatt include Memorial Sloan Kettering Cancer Center & Cayetano Heredia University.

Quality of life in patients with inflammatory bowel disease.

Abstract: To investigate the effect of inflammatory bowel disease (IBD) on the quality of life, we interviewed 43 patients with ulcerative colitis (UC) and 54 with Crohn's disease. Patients identified frequent and important problems in five areas. Primary bowel symptoms, systemic symptoms, and altered emotional function were common; functional and social impairment were less frequent. Systemic symptoms such as fatigue were more prevalent in patients with Crohn's disease. Apart from primary bowel complaints, patients seldom volunteered other facets of quality of life impairment; this was particularly true for impairment of emotional function. We conclude that despite troublesome intestinal and systemic symptoms, most patients with IBD avoid major disruption in work and personal lives. Physicians must inquire specifically about emotional problems relating to IBD; in particular, fear of surgery is important to address. Psychosocial interventions should be targeted to those patients with problems in this area.

Effect of HMGcoA Reductase Inhibitors on Stroke: A Meta-Analysis of Randomized, Controlled Trials

Abstract: Background: Stroke is a leading cause of death in the industrialized world, and hypercholesterolemia may be a risk factor for stroke Objective: To determine whether reducing cholesterol levels with HMGcoA (3-hydroxy-3-methylglutaryl coenzyme A) reductase inhibitors or other antilipidemic interventions reduces risk for nonfatal and fatal stroke Data Sources: A systematic search in the MEDLINE and EMBASE databases of the English-language and non-English-language literature published from 1966 through October 1996 Study Selection: All randomized, controlled trials of any cholesterol-lowering intervention that reported data on nonfatal and fatal strokes, on death from coronary heart disease, and on overall mortality were included Whether treatment effects differed according to the type of cholesterol-lowering intervention used was investigated Data Extraction: Trials were reviewed for methods, inclusion and exclusion criteria, and outcomes Data Synthesis: 28 trials (for a total of 49 477 study participants in the intervention group and 56 636 participants in the control group) were included The risk ratio for nonfatal and fatal stroke with HMGcoA reductase inhibitors was 076 (95% Cl, 062 to 092; test of heterogeneity, P > 02) The risk ratios for nonfatal and fatal stroke with fibrates, resins, and dietary interventions were all close to 10, and the difference between the HMGcoA reductase inhibitor effect and the pooled estimate for all other interventions would, under the null hypothesis, be unlikely to occur by chance (P = 001) Trials with HMGcoA reductase inhibitors also showed reductions in rates of death from coronary heart disease and overall mortality Conclusion: This meta-analysis of randomized, controlled trials suggests that in hyperlipidemic patients who have not previously had stroke, HMGcoA reductase inhibitors reduce the incidence of stroke

Quality of life in patients with chronic airflow limitation.

Abstract: One hundred patients with chronic airflow limitation (CAL) randomly selected from over 600 such patients seen in the previous 2 years at a respiratory referral centre were asked about the ways in which their lives were adversely effected by their lung problems. Major problem areas included dyspnoea on day-to-day activities, fatigue and certain areas of emotional function including embarrassment, depression, anxiety and frustration. Severity of airflow limitation was only weakly related to patients' problems. Patients did not volunteer items easily, and most problems were elicited by specific probes. In 36 subjects, relatives were asked about the patients' problems. Relatives tended to identify fewer items, but items identified were judged more important; there was a limited relation between spouses' and patients' assessment of CAL-related problems (Pearson's r = 0.42-0.60). These results suggest that physicians cannot rely on severity of airflow limitation as an indicator of the impact of CAL on patients' lives. Patients should be specifically asked about problem areas, especially emotional difficulties, and spouses' view of the problems should be obtained.

Transferring evidence from research into practice: 1. The role of clinical care research evidence in clinical decisions

Abstract: There is within medicine, somewhere beneath the pessimism and discouragement resulting from the disarray of the health care system and its stupendous cost, an undercurrent of almost outrageous optimism about what may lie ahead for the treatment of human disease if only we can keep learning.

Interpretation of rhinoconjunctivitis quality of life questionnaire data

Abstract: tion of both CP and cisplatin. Hypersensitivity to mannitol was reported as a cause of apparent hypersensitivity to cisplatin. 6 In case 2 the result of a skin test with mannitol was negative, whereas the result of a skin test with the commercial formulation containing CP and mannitol was positive, suggesting that CP was solely responsible for the hypersensitivity reaction. In addition to the clinical tolerance induced by the desensitization protocol, skin responses to intradermal CP diminished. As shown in Table I, the ratio between wheal sizes of CP and histamine decreased more than 3.5 times after the desensitization. The observation of wheal-and-flare responses becoming negative has already been described in penicillin desensitization. 7 This phenomenon supports an antigen-specific desensitization. The rate at which the drug concentration increases in the extracellular fluid seems to be the most important factor in a successful outcome of desensitization. As suggested by our two patients, this rate can differ in each individual case. We conclude that the 4-hour desensitization protocol may not be suitable for all patients allergic to CP, whereas a modified prolonged protocol seems to be more tolerable. Until further data have been accumulated, the short protocol may be at tempted initially but should be replaced by the prolonged protocol if adverse effects appear. The prolonged protocol seems to be both safe and efficacious with regard to anti tumor activity.

Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement

Abstract: David Moher and colleagues introduce PRISMA, an update of the QUOROM guidelines for reporting systematic reviews and meta-analyses

Preferred reporting items for systematic reviews and meta-analyses: the PRISMA Statement.

Abstract: Systematic reviews and meta-analyses have become increasingly important in health care. Clinicians read them to keep up to date with their field,1,2 and they are often used as a starting point for developing clinical practice guidelines. Granting agencies may require a systematic review to ensure there is justification for further research,3 and some health care journals are moving in this direction.4 As with all research, the value of a systematic review depends on what was done, what was found, and the clarity of reporting. As with other publications, the reporting quality of systematic reviews varies, limiting readers' ability to assess the strengths and weaknesses of those reviews. Several early studies evaluated the quality of review reports. In 1987, Mulrow examined 50 review articles published in 4 leading medical journals in 1985 and 1986 and found that none met all 8 explicit scientific criteria, such as a quality assessment of included studies.5 In 1987, Sacks and colleagues6 evaluated the adequacy of reporting of 83 meta-analyses on 23 characteristics in 6 domains. Reporting was generally poor; between 1 and 14 characteristics were adequately reported (mean = 7.7; standard deviation = 2.7). A 1996 update of this study found little improvement.7 In 1996, to address the suboptimal reporting of meta-analyses, an international group developed a guidance called the QUOROM Statement (QUality Of Reporting Of Meta-analyses), which focused on the reporting of meta-analyses of randomized controlled trials.8 In this article, we summarize a revision of these guidelines, renamed PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses), which have been updated to address several conceptual and practical advances in the science of systematic reviews (Box 1). Box 1 Conceptual issues in the evolution from QUOROM to PRISMA

Measuring inconsistency in meta-analyses

Abstract: Cochrane Reviews have recently started including the quantity I 2 to help readers assess the consistency of the results of studies in meta-analyses. What does this new quantity mean, and why is assessment of heterogeneity so important to clinical practice? Systematic reviews and meta-analyses can provide convincing and reliable evidence relevant to many aspects of medicine and health care.1 Their value is especially clear when the results of the studies they include show clinically important effects of similar magnitude. However, the conclusions are less clear when the included studies have differing results. In an attempt to establish whether studies are consistent, reports of meta-analyses commonly present a statistical test of heterogeneity. The test seeks to determine whether there are genuine differences underlying the results of the studies (heterogeneity), or whether the variation in findings is compatible with chance alone (homogeneity). However, the test is susceptible to the number of trials included in the meta-analysis. We have developed a new quantity, I 2, which we believe gives a better measure of the consistency between trials in a meta-analysis. Assessment of the consistency of effects across studies is an essential part of meta-analysis. Unless we know how consistent the results of studies are, we cannot determine the generalisability of the findings of the meta-analysis. Indeed, several hierarchical systems for grading evidence state that the results of studies must be consistent or homogeneous to obtain the highest grading.2–4 Tests for heterogeneity are commonly used to decide on methods for combining studies and for concluding consistency or inconsistency of findings.5 6 But what does the test achieve in practice, and how should the resulting P values be interpreted? A test for heterogeneity examines the null hypothesis that all studies are evaluating the same effect. The usual test statistic …

Bias in meta-analysis detected by a simple, graphical test

Abstract: Objective: Funnel plots (plots of effect estimates against sample size) may be useful to detect bias in meta-analyses that were later contradicted by large trials. We examined whether a simple test of asymmetry of funnel plots predicts discordance of results when meta-analyses are compared to large trials, and we assessed the prevalence of bias in published meta-analyses. Design: Medline search to identify pairs consisting of a meta-analysis and a single large trial (concordance of results was assumed if effects were in the same direction and the meta-analytic estimate was within 30% of the trial); analysis of funnel plots from 37 meta-analyses identified from a hand search of four leading general medicine journals 1993-6 and 38 meta-analyses from the second 1996 issue of the Cochrane Database of Systematic Reviews . Main outcome measure: Degree of funnel plot asymmetry as measured by the intercept from regression of standard normal deviates against precision. Results: In the eight pairs of meta-analysis and large trial that were identified (five from cardiovascular medicine, one from diabetic medicine, one from geriatric medicine, one from perinatal medicine) there were four concordant and four discordant pairs. In all cases discordance was due to meta-analyses showing larger effects. Funnel plot asymmetry was present in three out of four discordant pairs but in none of concordant pairs. In 14 (38%) journal meta-analyses and 5 (13%) Cochrane reviews, funnel plot asymmetry indicated that there was bias. Conclusions: A simple analysis of funnel plots provides a useful test for the likely presence of bias in meta-analyses, but as the capacity to detect bias will be limited when meta-analyses are based on a limited number of small trials the results from such analyses should be treated with considerable caution. Key messages Systematic reviews of randomised trials are the best strategy for appraising evidence; however, the findings of some meta-analyses were later contradicted by large trials Funnel plots, plots of the trials9 effect estimates against sample size, are skewed and asymmetrical in the presence of publication bias and other biases Funnel plot asymmetry, measured by regression analysis, predicts discordance of results when meta-analyses are compared with single large trials Funnel plot asymmetry was found in 38% of meta-analyses published in leading general medicine journals and in 13% of reviews from the Cochrane Database of Systematic Reviews Critical examination of systematic reviews for publication and related biases should be considered a routine procedure

Global Cancer Statistics 2020: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries.

Abstract: This article provides an update on the global cancer burden using the GLOBOCAN 2020 estimates of cancer incidence and mortality produced by the International Agency for Research on Cancer. Worldwide, an estimated 19.3 million new cancer cases (18.1 million excluding nonmelanoma skin cancer) and almost 10.0 million cancer deaths (9.9 million excluding nonmelanoma skin cancer) occurred in 2020. Female breast cancer has surpassed lung cancer as the most commonly diagnosed cancer, with an estimated 2.3 million new cases (11.7%), followed by lung (11.4%), colorectal (10.0 %), prostate (7.3%), and stomach (5.6%) cancers. Lung cancer remained the leading cause of cancer death, with an estimated 1.8 million deaths (18%), followed by colorectal (9.4%), liver (8.3%), stomach (7.7%), and female breast (6.9%) cancers. Overall incidence was from 2-fold to 3-fold higher in transitioned versus transitioning countries for both sexes, whereas mortality varied <2-fold for men and little for women. Death rates for female breast and cervical cancers, however, were considerably higher in transitioning versus transitioned countries (15.0 vs 12.8 per 100,000 and 12.4 vs 5.2 per 100,000, respectively). The global cancer burden is expected to be 28.4 million cases in 2040, a 47% rise from 2020, with a larger increase in transitioning (64% to 95%) versus transitioned (32% to 56%) countries due to demographic changes, although this may be further exacerbated by increasing risk factors associated with globalization and a growing economy. Efforts to build a sustainable infrastructure for the dissemination of cancer prevention measures and provision of cancer care in transitioning countries is critical for global cancer control.