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G H Guyatt

Publications and source records attributed to G H Guyatt.

At least 19 recordsLinked to original sources
PubMed2006

Validation of a symptom diary for patients with gastro-oesophageal reflux disease.

BACKGROUND: Symptom diaries are potentially attractive but, because of concerns about patient compliance, they have had limited use in clinical trials. We assessed the validity and responsiveness of a symptom diary for patients with gastro-oesophageal reflux disease. METHODS: We included 215 patients with gastro-oesophageal reflux disease after starting treatment for 4 weeks with 40 mg esomeprazole once daily. Patients recorded whether they experienced night-time heartburn (yes/no), the severity of daytime heartburn on a scale from 1 (no heartburn) to 4 (severe heartburn) and their antacid use. Patients also completed a number of disease-specific and preference-based Health-related Quality of Life questionnaires at baseline and follow-up. RESULTS: Consistent with a priori predictions, daytime heartburn showed moderate to strong correlations with the Quality of Life in Reflux and Dyspepsia questionnaire (0.36-0.67) and four scales of symptom severity (0.36-0.70) for baseline, follow-up and change scores, but low correlations with the Standard Gamble. Responsiveness of the daytime heartburn item was excellent with a mean change from baseline to follow-up of -1.3 (95% CI -1.4 to -1.1) and a standardized response mean of 1.33 while responsiveness of the daily antacid use item was moderate (mean change scores -1.8 tablets taken, 95% CI -2.3 to -1.3 and standardized response mean of 0.64). CONCLUSIONS: The excellent psychometric properties of this simple gastro-oesophageal reflux disease diary make it an attractive measure for future trials.

Antacids↗
PubMed2005

A randomised trial to evaluate the self-administered standardised chronic respiratory questionnaire.

The original chronic respiratory questionnaire (CRQ), one of the most widely used measures of health-related quality of life (HRQL) in chronic respiratory disease (CRD), is traditionally interviewer administered (IA) and includes an individualised dyspnoea domain. The present authors studied the impact of self-administered (SA) and standardised dyspnoea questions on CRQ measurement properties. In a factorial design multicentre trial, 177 patients with CRD (mean age 67.7 yrs; mean forced expiratory volume in one second per cent predicted 44.6%) were randomised to CRQ-IA (n = 86) or CRQ-SA (n = 91), and to initially complete the standardised or individualised items before and after respiratory rehabilitation. While maintaining validity, the CRQ-SA proved more responsive to changes in HRQL than the CRQ-IA in all domains. Compared with the standardised dyspnoea domain, the individualised dyspnoea domain indicated greater responsiveness. The correlations of baseline scores and change scores with other HRQL instruments indicated good validity of the CRQ-SA. In conclusion, self-administration and standardisation of the chronic respiratory questionnaire maintains validity and responsiveness relative to the interviewer-administered chronic respiratory questionnaire. These results challenge the assumption that interviewer-administered questionnaires are superior to self-administered questionnaires in older patients with chronic respiratory disease.

Adaptation, Physiological↗
PubMed2004

Do physicians correctly assess patient symptom severity in gastro-oesophageal reflux disease?

BACKGROUND: The accuracy of physicians' assessment of the severity of gastro-oesophageal reflux disease is unclear. AIM: To correlate physician and patient assessment of gastro-oesophageal reflux disease severity and its response to treatment. METHODS: Adult uninvestigated gastro-oesophageal reflux disease patients (n = 217) completed symptom and health-related quality of life questionnaires at baseline and after treatment with esomeprazole 40 mg p.o. daily. Pearson coefficients quantified correlations between physician assessments and patient responses. RESULTS: At baseline, the strongest correlations were heartburn severity (0.31), overall symptom severity (0.44) and a domain of the quality of life in reflux and dyspepsia questionnaire (0.31) (P < 0.001). Correlations of change with treatment were greater than baseline correlations: heartburn (0.39), overall symptoms (0.50) and global rate of change -- stomach problems (0.72, all P < 0.001). The mean difference between the physicians' assessment of change and the patients' global rating of change was 0.20 (95% confidence intervals: 0.10-0.29) with physicians overestimating benefit. CONCLUSIONS: Correlations were often significant, although weak to moderate and better with symptom severity than with health-related quality of life instruments as well as with change after therapy than at baseline. Increasing attention to health-related quality of life may help physicians better understand patients' experience. In clinical trials, treatment success should be assessed by the patient as well as the physician.

Adolescent↗
PubMed2004

Digitalis for treatment of congestive heart failure in patients in sinus rhythm.

BACKGROUND: Digitalis glycosides have been in clinical use in the treatment of congestive heart failure (CHF) for more than 200 years. In recent years several trials have been conducted to address concerns about efficacy and toxicity. Although a systematic review of the literature was published in 1990, an update is required to include more current trials. OBJECTIVES: To examine the effectiveness of digitalis glycosides in treating CHF in patients with normal sinus rhythm. To examine the effect of digitalis in patients taking diuretics, angiotensin converting enzyme inhibitors, and beta-blockers; patients with varying severity and duration of disease; patients with prior exposure to digitalis vs. no prior exposure; and patients with "CHF due to systolic dysfunction" vs. "CHF with preserved systolic function." SEARCH STRATEGY: The Cochrane Central Register of Controlled Trials (CENTRAL) 2003 Issue 4, MEDLINE (1966 to December 2003) and EMBASE (1990 to December 2003) were searched. Dissertation Abstracts and annual meeting abstracts of the American Heart Association, American College of Cardiology, and European Society of Cardiology were also searched from 1996-2003. In addition, reference lists provided by the pharmaceutical industry (Glaxo Wellcome Inc.) were searched. SELECTION CRITERIA: Included were randomized placebo-controlled trials of 20 or more adult patients of either sex with symptomatic CHF who were studied for seven weeks or more. Excluded were trials in which the prevalence of atrial fibrillation was 2% or greater, or in which any arrhythmia that might compromise cardiac function or any potentially reversible cause of CHF such as acute ischemic heart disease or myocarditis was present. DATA COLLECTION AND ANALYSIS: Articles selected from the searches described above were evaluated as a joint effort of the coauthors. The staff of the Cochrane Heart Group ran searches on the Cochrane Central Register of Controlled Trials. MAIN RESULTS: Thirteen articles meeting the defined criteria were identified, and major endpoints of mortality, hospitalization, and clinical status, based respectively upon 8, 4, and 12 of these selected studies, were recorded and analyzed. The data show that there is no evidence of a difference in mortality between treatment and control groups, whereas digitalis therapy is associated with a lower rate of hospitalization and of clinical deterioration. REVIEWERS' CONCLUSIONS: The literature indicates that digitalis has a useful role in the treatment of patients with CHF who are in normal sinus rhythm.

Cardiotonic Agents↗
PubMed2004

The influence of lung volume reduction surgery on exercise in patients with COPD.

Although the influence of lung volume reduction surgery (LVRS) on incremental- and constant-power exercise is important in the evaluation of this procedure for patients with chronic obstructive pulmonary disease (COPD), it is rarely reported even in large randomised controlled trials. This report describes 39 patients with severe COPD ((mean +/- SE) forced expiratory volume in one second 32 +/- 2% pred, functional residual capacity 195 +/- 6% pred) who participated in a randomised controlled trial of LVRS and who completed incremental exercise tests at 6 months as well as endurance tests (constant power of 25 +/- 1 W) at 3, 9 and 12 months. Peak oxygen uptake (V'O2,pk) was similar between the treatment (n = 19) and control groups (n = 20) at baseline. After LVRS, the treatment group had a significantly greater V'O2,pk (mean difference (95% CI) 1.28 (0.07-2.50) mL x kg x min(-1)) and power (13 (6-20) W). The treatment group achieved a significantly greater minute ventilation (7.1 (2.9-11.3) L x min(-1)) with a greater tidal volume (0.16 (0.04-0.28) L). Baseline endurance was similar between groups. After surgery, there were significant between-group differences in endurance time, which were maintained at 12 months (7.3 (3.9-10.8) min). Lung volume reduction surgery is associated with an increase in exercise capacity and endurance, as compared with conventional medical treatment.

Aged↗
PubMed2002

Clinical estimation of trunk position among mechanically ventilated patients.

OBJECTIVES: Trunk position at 45 degrees from the horizontal is associated with a decreased risk of gastroesophageal aspiration. The objectives of this study were to determine the accuracy of trunk flexion estimates compared to a reference standard measurement, and to determine agreement about trunk flexion among ICU clinicians. DESIGN: Prospective observational study. SETTING: Two university-affiliated medical-surgical ICUs. PATIENTS AND PARTICIPANTS: Thirty-three mechanically ventilated ICU patients, seven residents, two fellows, three intensivists, and twenty-eight bedside nurses. INTERVENTIONS: Prospectively, concurrently, and independently during rounds, one bedside nurse, one resident, one fellow, and one intensivist clinically estimated the trunk flexion of mechanically ventilated patients. To record the reference standard, a trained investigator measured trunk position in the vertical plane using a goniometer. MEASUREMENTS AND RESULTS: We made 438 clinical assessments on 33 patients aged 57.2+/-19.4 (SD) years with an APACHE II score of 27.3+/-9.4. Mean trunk flexion estimates were: nurses 24.3+/-12.3 degrees from the horizontal, residents 20.2+/-13.7, fellows 20.3+/-10.8, and intensivists 21.1+/-13.1 compared to the reference standard measurement 16.2+/-9.0 degrees. The accuracy of trunk flexion estimates was fair to moderate [intraclass correlation for reference standard versus nurses (ICC 0.42), residents (ICC 0.52), fellows (ICC 0.36), and intensivists (ICC 0.55)]. The agreement among different groups of clinicians was moderate. CONCLUSIONS: In mechanically ventilated patients, we found that clinical estimates of trunk position were moderately good, agreement amongst caregivers was moderately good, but that all clinicians tended to overestimate the angle of semirecumbency.

APACHE↗
PubMed2002

Nocturnal non-invasive positive pressure ventilation for stable chronic obstructive pulmonary disease.

BACKGROUND: Nocturnal non-invasive positive pressure ventilation (NIPPV) might be beneficial in stable hypercapnic patients with chronic obstructive pulmonary disease (COPD). However, evidence remains equivocal as conflicting results have been published. OBJECTIVES: To determine the effect of nocturnal non-invasive positive pressure ventilation via nasal mask or face mask in patients with COPD. SEARCH STRATEGY: An initial search was carried out using the Cochrane Airways Group COPD RCT register using the search terms: (nasal ventilat* OR positive pressure OR NIPPV). An additional search was done by hand searching of abstracts from meetings of the American Thoracic Society, British Thoracic Society and European Respiratory Society. SELECTION CRITERIA: Randomised controlled trials in stable patients with COPD that compared nocturnal non-invasive positive pressure ventilation plus standard therapy with standard therapy alone. DATA COLLECTION AND ANALYSIS: Data extraction was performed by two independent reviewers. MAIN RESULTS: The only outcome for which the 95% confidence interval excluded zero was PI max. The 95% confidence interval (CI) of the other outcomes included zero. These included FEV1,FVC, PaCO2, sleep efficiency and 6-minute walking distance (6MWD). The mean effect on 6MWD was modest at 27.5 m, but the 95% CI were wide (-28.1, 81.8 m) suggesting that some patients had a big improvement. Such patients could not be identified a priori. REVIEWER'S CONCLUSIONS: Nocturnal NIPPV for at least 3 months in hypercapnic patients with stable COPD had no consistent clinically or statistically significant effect on lung function, gas exchange, respiratory muscle strength, sleep efficiency or exercise tolerance. However, the small sample sizes of these studies precludes a definite conclusion regarding the effects of NIPPV in COPD.

Humans↗
PubMed2002

Pulmonary rehabilitation for chronic obstructive pulmonary disease.

BACKGROUND: The widespread application pulmonary rehabilitation in chronic obstructive pulmonary disease (COPD) should be preceded by demonstrable improvements in function attributable to the programs. This review updates that reported by Lacasse et al Lancet 1996; 748:1115-1119. OBJECTIVES: To determine the impact of rehabilitation on health-related quality of life (QoL) and exercise capacity in patients with COPD. SEARCH STRATEGY: The 14 randomized controlled trials (RCTs) included in the original meta-analysis were included. Additional RCTs were identified from the Cochrane Airways Group's registry of COPD RCTs using the strategy: [exp, lung diseases, obstructive] and [exp, rehabilitation or exp, exercise therapy] and [research design or longitudinal studies or evaluation study or randomized controlled trial]. Abstracts presented at American Thoracic Society 1980-2000, American College of Chest Physicians 1980-2000 and European Respiratory Society 1987-2000 were also searched. SELECTION CRITERIA: RCTs of rehabilitation in patients with COPD in which quality of life (QoL) and/or functional (FEC) or maximal (MEC) exercise capacity were measured. Rehabilitation was defined as exercise training for at least 4 weeks with or without education and/or psychological support. Control groups received conventional community care without rehabilitation. DATA COLLECTION AND ANALYSIS: Weighted mean differences (WMD) were calculated using a random-effects model. Missing data from the primary study reports were requested from the authors. MAIN RESULTS: 23 RCTs met the inclusion criteria. Statistically significant improvements were found for all the outcomes. In three important domains of QoL (Chronic Respiratory Questionnaire scores for Dyspnea, Fatigue and Mastery), the effect was larger than the minimal clinically important difference of 0.5 units using this instrument. For example Dyspnoea score: WMD 0.98 units, 95% Confidence Interval (95% CI) 0.74 - 1.22 units; n=9 trials. For FEC and MEC, the effect was small and a little below the threshold of clinical significance for the 6- minute walking distance: WMD 49 m, 95% CI: 26 - 72 m; n=10 trials. REVIEWER'S CONCLUSIONS: Rehabilitation relieves dyspnea and fatigue and enhances patients' sense of control over their condition. These improvements are moderately large and clinically significant. The average improvement in exercise capacity was modest. Rehabilitation forms an important component of the management of COPD.

Dyspnea↗
PubMed2002

Interobserver and intraobserver variation in the assessment of the healing of tibial fractures after intramedullary fixation.

The reliability of the radiological assessment of the healing of tibial fractures remains undetermined. We examined the inter- and intraobserver agreement of the healing of such fractures among four orthopaedic trauma surgeons who, on two separate occasions eight weeks apart, independently assessed the radiographs of 30 patients with fractures of the tibial shaft which had been treated by intramedullary fixation. The radiographs were selected from a database to represent fractures at various stages of healing. For each radiograph, the surgeon scored the degree of union, quantified the number of cortices bridged by callus or with a visible fracture line, described the extent and quality of the callus, and provided an overall rating of healing. The interobserver chance-corrected agreement using a quadratically weighted kappa (kappa) statistic in which values of 0.61 to 0.80 represented substantial agreement were as follows: radiological union scale (kappa= 0.60); number of cortices bridged by callus (kappa = 0.75); number of cortices with a visible fracture line (kappa= 0.70); the extent of the callus (kappa = 0.57); and general impression of fracture healing (kappa = 0.67). The intraobserver agreement of the overall impression of healing (kappa = 0.89) and the number of cortices bridged by callus (kappa = 0.82) or with a visible fracture line (kappa = 0.83) was almost perfect. There are no validated scales which allow surgeons to grade fracture healing radiologically. Among those examined, the number of cortices bridged by bone appears to be a reliable, and easily measured radiological variable to assess the healing of fractures after intramedullary fixation.

Bony Callus↗
PubMed2001

The attributable mortality and length of intensive care unit stay of clinically important gastrointestinal bleeding in critically ill patients.

OBJECTIVE: To estimate the mortality and length of stay in the intensive care unit (ICU) attributable to clinically important gastrointestinal bleeding in mechanically ventilated critically ill patients. DESIGN: Three strategies were used to estimate the mortality attributable to bleeding in two multicentre databases. The first method matched patients who bled with those who did not (matched cohort), using duration of ICU stay prior to the bleed, each of six domains of the Multiple Organ Dysfunction Score (MODS) measured 3 days prior to the bleed, APACHE II score, age, admitting diagnosis, and duration of mechanical ventilation. The second approach employed Cox proportional hazards regression to match bleeding and non-bleeding patients (model-based matched cohort). The third method, instead of matching, derived estimates based on regression modelling using the entire population (regression method). Three parallel analyses were conducted for the length of ICU stay attributable to clinically important bleeding. SETTING: Sixteen Canadian university-affiliated ICUs. PATIENTS: A total of 1666 critically ill patients receiving mechanical ventilation for at least 48 hours. MEASUREMENTS: We prospectively collected data on patient demographics, APACHE II score, admitting diagnosis, daily MODS, clinically important bleeding, length of ICU stay, and mortality. Independent adjudicators determined the occurrence of clinically important gastrointestinal bleeding, defined as overt bleeding in association with haemodynamic compromise or blood transfusion. RESULTS: Of 1666 patients, 59 developed clinically important gastrointestinal bleeding. The mean APACHE II score was 22.9 +/- 8.6 among bleeding patients and 23.3 +/- 7.7 among non-bleeding patients. The risk of death was increased in patients with bleeding using all three analytic approaches (matched cohort method: relative risk [RR]= 2.9, 95% confidence interval (CI)= 1.6-5.5; model-based matched cohort method: RR = 1.8, 95% CI = 1.1-2.9; and the regression method: RR = 4.1, 95% CI = 2.6-6.5). However, this was not significant for the adjusted regression method (RR = 1.0, 95% CI = 0.6-1.7). The median length of ICU stay attributable to clinically important bleeding for these three methods, respectively, was 3.8 days (95% CI = -0.01 to 7.6 days), 6.7 days (95% CI = 2.7-10.7 days), and 7.9 days (95% CI = 1.4-14.4 days). CONCLUSIONS: Clinically important upper gastrointestinal bleeding has an important attributable morbidity and mortality, associated with a RR of death of 1-4 and an excess length of ICU stay of approximately 4-8 days.

APACHE↗
PubMed2001

Reviewing the reviewers: the quality of reporting in three secondary journals.

BACKGROUND: Secondary journals such as ACP Journal Club (ACP), Journal Watch (JW) and Internal Medicine Alert (IMA) have enormous potential to help clinicians remain up to date with medical knowledge. However, for clinicians to evaluate the validity and applicability of new findings, they need information on the study design, methodology and results. METHODS: Beginning with the first issue in March 1997, we selected 50 consecutive summaries of studies addressing therapy or prevention and internal medicine content from each of the ACP, JW and IMA. We evaluated the summaries for completeness of reporting key aspects of study design, methodology and results. RESULTS: All of the summaries in ACP reported study design, as compared with 72% of the summaries in JW and IMA (p < 0.001). In summaries of randomized controlled trials the 3 secondary journals were similar in reporting concealment of patient allocation (none reported this), blinding status of participants (ACP 62%, JW 70% and IMA 70% [p = 0.7]), blinding status of health care providers (ACP 12%, JW 4% and IMA 4% [p = 0.4]) and blinding status of judicial assessors of outcomes (ACP 4%, JW 4% and IMA 0% [p = 0.4]). ACP was the only one to report whether investigators conducted an intention-to-treat analysis (in 38% of summaries [p < 0.001]), and it was more likely than the other 2 journals to report the precision of the treatment effect (as a p value or 95% confidence interval) (ACP 100%, JW 0% and IMA 55% [p < 0.001]). INTERPRETATION: Although ACP provided more information on study design, methodology and results, all 3 secondary journals often omitted important information. More complete reporting is necessary for secondary journals to fulfill their potential to help clinicians evaluate the medical literature.

Chi-Square Distribution↗
PubMed2001

Physician interpretations and textbook definitions of blinding terminology in randomized controlled trials.

CONTEXT: When clinicians assess the validity of randomized controlled trials (RCTs), they commonly evaluate the blinding status of individuals in the RCT. The terminology authors often use to convey blinding status (single, double, and triple blinding) may be open to various interpretations. OBJECTIVE: To determine physician interpretations and textbook definitions of RCT blinding terms. DESIGN AND SETTING: Observational study undertaken at 3 Canadian university tertiary care centers between February and May 1999. PARTICIPANTS: Ninety-one internal medicine physicians who responded to a survey. MAIN OUTCOME MEASURES: Respondents identified which of the following groups they thought were blinded in single-, double-, and triple-blinded RCTs: participants, health care providers, data collectors, judicial assessors of outcomes, data analysts, and personnel who write the article. Definitions from 25 systematically identified textbooks published since 1990 providing definitions for single, double, or triple blinding. RESULTS: Physician respondents identified 10, 17, and 15 unique interpretations of single, double, and triple blinding, respectively, and textbooks provided 5, 9, and 7 different definitions of each. The frequencies of the most common physician interpretation and textbook definition were 75% (95% confidence interval [CI], 65%-83%) and 74% (95% CI, 52%-90%) for single blinding, 38% (95% CI, 28%-49%) and 43% (95% CI, 24%-63%) for double blinding, and 18% (95% CI, 10%-28%) and 14% (95% CI, 0%-58%) for triple blinding, respectively. CONCLUSIONS: Our study suggests that both physicians and textbooks vary greatly in their interpretations and definitions of single, double, and triple blinding. Explicit statements about the blinding status of specific groups involved in RCTs should replace the current ambiguous terminology.

Double-Blind Method↗
PubMed2001

Digitalis for treatment of congestive heart failure in patients in sinus rhythm.

BACKGROUND: Digitalis glycosides have been in clinical use in the treatment of congestive heart failure for more than 200 years. In recent years several trials have been conducted to address concerns about efficacy and toxicity. Although a systematic review of the literature was recently published, an update is required to include more current trials. OBJECTIVES: To examine the effectiveness of digitalis glycosides in treating congestive heart failure in patients with normal sinus rhythm. To examine the effect of digitalis in patients taking diuretics, ACE inhibitors, and beta blockers; patients with varying severity and duration of disease; patients with prior exposure to digitalis vs. no prior exposure; and patients with diastolic vs. systolic dysfunction. SEARCH STRATEGY: Electronic databases were searched between 1966 and 2000. Dissertation Abstracts and annual meeting abstracts of the American Heart Association, American College of Cardiology, and European Society of Cardiology were searched from 1996-2000. In addition, reference lists provided by the pharmaceutical industry (Glaxo Wellcome Inc.) were searched. SELECTION CRITERIA: Included were randomized placebo-controlled trials of 20 or more adult patients of either sex with symptomatic congestive heart failure who were studied for seven weeks or more. Excluded were trials in which the prevalence of atrial fibrillation was 2% or greater, or in which any arrhythmia that might compromise cardiac function or any potentially reversible cause of heart failure such as acute ischemic heart disease or myocarditis was present. DATA COLLECTION AND ANALYSIS: Articles selected from the searches described above were reviewed by one of the coauthors, and validated by staff from the central office of the Heart Collaborative Review Group in Bristol, UK. MAIN RESULTS: Eleven articles meeting the defined criteria were identified, and major endpoints of mortality, hospitalization, and clinical status, based respectively upon on 8, 4, and 10 of these selected studies, were recorded and analyzed. The data show that there is no difference in mortality between treatment and control groups, whereas digitalis therapy is associated with a lower rate of hospitalization and of clinical deterioration. REVIEWER'S CONCLUSIONS: The literature indicates that digitalis has a useful role in the treatment of patients with congestive heart failure who are in normal sinus rhythm.

Cardiotonic Agents↗