Gordon H. Guyatt

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advantages and disadvantages but also by their confidence in these estimates. The cartoon depicting the weather forecaster’s uncertainty captures the difference between an assessment of the likelihood of an outcome and the confidence in that assessment (figure). The usefulness of an estimate of the magnitude of intervention effects depends on our confidence(More)
In recent years quality of life instruments have been featured as primary outcomes in many randomized trials. One of the challenges facing the investigator using such measures is determining the significance of any differences observed, and communicating that significance to clinicians who will be applying the trial results. We have developed an approach to(More)
International guidelines on asthma management indicate that the primary goal of treatment should be optimum asthma control. The aim of this study was to develop and validate the Asthma Control Questionnaire (ACQ). The authors generated a list of all symptoms used to assess control and sent it to 100 asthma clinicians who were members of guidelines(More)
Since the relationships between pulmonary function, exercise capacity, and functional state or quality of life are generally weak, a self report questionnaire has been developed to determine the effect of treatment on quality of life in clinical trials. One hundred patients with chronic airflow limitation were asked how their quality of life was affected by(More)
There are many different definitions of evidence based medicine. One of the most is Evidence Based Medicine? Users' Guide to the Medical Literature, 3rd ed. Oxman AD, Sackett DL, Guyatt GH et al. Users' guides to the medical literature. I. How to get started. The Evidence-Based Medicine Working Group. JAMA. 1993. Download Users Guides To The Medical(More)
When little or no data directly comparing two treatments are available, investigators often rely on indirect comparisons from studies testing the treatments against a control or placebo. One approach to indirect comparison is to pool findings from the active treatment arms of the original controlled trials. This approach offers no advantage over a(More)
This study was carried out to determine whether the minimal important difference, in evaluative quality of life instruments which use a 7-point scale, is similar across individual domains and for both improvement and deterioration. Thirty nine adults with asthma were studied, using an 8 week cohort with assessments at 0, 4 and 8 weeks. The outcomes were the(More)
This article introduces the approach of GRADE to rating quality of evidence. GRADE specifies four categories-high, moderate, low, and very low-that are applied to a body of evidence, not to individual studies. In the context of a systematic review, quality reflects our confidence that the estimates of the effect are correct. In the context of(More)
BACKGROUND In the past only physiological and clinical outcomes have been used to assess the effect of asthma interventions and the effect of the intervention on the lives of the patients has not been determined. The objective of this study was to assess health related impairment of quality of life in adult asthmatic patients and to develop a questionnaire(More)
Reliability, the ratio of the variance attributable to true differences among subjects to the total variance, is an important attribute of psychometric measures. However, it is possible for instruments to be reliable, but unresponsive to change; conversely, they may show poor reliability but excellent responsiveness. This is especially true for instruments(More)