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Showing papers by "Gordon H. Guyatt published in 1998"


Journal ArticleDOI
TL;DR: This study examined factors associated with ventilator-associated pneumonia and explored baseline and time-dependent characteristics, including measures of illness severity, factors relating to mechanical ventilation, variables in the gastropulmonary route of infection, and drug exposure.
Abstract: Background: Understanding the risk factors for ventilator-associated pneumonia can help to assess prognosis and devise and test preventive strategies Objective: To examine the baseline and time-de

903 citations


Journal ArticleDOI
28 Feb 1998-BMJ
TL;DR: For some questionnaires, it is known that the smallest change in score that patients consider important is 0.5 per question, even if the mean difference between a treatment and a control is appreciably less than the smallest changes that is important, treatment may have an important impact on many patients.
Abstract: The need to measure the impact of treatments on health related quality of life has led to a rapid increase in the variety of instruments available and in their use as measures of outcome in clinical trials. One limitation of instruments that purport to measure health related quality of life is difficulty interpreting their results. In the past decade, investigators have progressed in making these questionnaire results interpretable. For example, we have shown that when questionnaires present response options in the form of seven point scales with verbal descriptions for each option (see box), the smallest difference that patients consider important is often approximately 0.5 per question. A moderate difference corresponds to a change of approximately 1.0 per question, and changes of greater than 1.5 can be considered large. Thus, for example, in a domain with four items, patients will consider a 1 point change in two or more items as important. This finding applies across different areas of function, including dyspnoea, fatigue, and emotional function in patients with chronic airflow limitation1; and symptoms, emotional function, and activity limitations in adults2 and children3 with asthma, parents of children with asthma,4 and adults with rhinoconjunctivitis.5 Initially, we used comparisons in the same patient to establish this difference, but more recently we have replicated this finding using differences between patients.6 #### Summary points Several questionnaires on quality of life related to health are available, but interpreting their results may be difficult For some questionnaires, we now know that the smallest change in score that patients consider important is 0.5 Even if the mean difference between a treatment and a control is appreciably less than the smallest change that is important, treatment may have an important impact on many patients A method for estimating the proportion of patients who …

512 citations


Journal ArticleDOI
TL;DR: Important change appears to be dependent on patients' initial RMQ scores, and subsequent inquiry using different hypotheses would add support to the estimates of important change found in this study.
Abstract: Background and Purpose. This study estimated the Roland-Morris Back Pain Questionnaire's (RMQ) change score that best classified patients as those who had achieved an important change and those who had not achieved an important change. The study also investigated whether the estimate of change was dependent on patients' initial scores. Subjects and Methods. The RMQ was administered to 226 patients with low back pain of less than 6 weeks' duration during their initial visit for physical therapy and following 3 to 6 weeks of treatment. A global rating of change was used to classify patients as those who had changed an important amount and those who had not changed. Receiver operating characteristic curves were used to identify the RMQ change score that most accurately classified patients with respect to important change. This analysis was repeated for 5 overlapping subsamples of patients with initial scores 0 to 8, 5 to 12, 9 to 16, 13 to 20, and 17 to 24. Results. The area under the receiver operating characteristic curves increased when patients' initial scores were taken into account. Estimates of important change were 2, 4, 5, 8, and 8 for the initial score intervals mentioned above. Conclusion and Discussion. Important change appears to be dependent on patients' initial RMQ scores. Subsequent inquiry using different hypotheses would add support to the estimates of important change found in this study. [ ARTICLE][1] [1]: /lookup/volpage/78/1197?iss=11

394 citations


Journal ArticleDOI
TL;DR: A questionnaire that promises to be useful in measuring health-related quality of life in women with polycystic ovary syndrome is constructed and tested prior to, or concurrent with, its use in randomized trials of new treatment approaches.
Abstract: Objective: To develop a self-administered questionnaire for measuring health-related quality of life (HRQL) in women with polycystic ovary syndrome (PCOS). Methods: We identified a pool of 182 items potentially relevant to women with PCOS through semistructured interviews with PCOS patients, a survey of health professionals who worked closely with PCOS women, and a literature review. One hundred women with PCOS completed a questionnaire in which they told us whether the 182 items were relevant to them and, if so, how important the issue was in their daily lives. We included items endorsed by at least 50% of women in the analysis plus additional items considered crucial by clinicians and an important subgroup of patients in a factor analysis. We chose items for the final questionnaire taking into account both item impact (the frequency and importance of the items) and the results of the factor analysis. Results: Over 50% of the women with PCOS labelled 47 items as important to them. Clinicians chose 5 addi...

290 citations


Journal ArticleDOI
14 Oct 1998-JAMA
TL;DR: Computer-derived algorithms that depend on clinical examination and ECG findings might improve the classification of patients according to the probability that an MI is causing their chest pain.
Abstract: When faced with a patient with acute chest pain, clinicians must distinguish myocardial infarction (MI) from all other causes of acute chest pain. If MI is suspected, current therapeutic practice includes deciding whether to administer thrombolysis or primary percutaneous transluminal coronary angioplasty and whether to admit patients to a coronary care unit. The former decision is based on electrocardiographic (ECG) changes, including ST-segment elevation or left bundle-branch block, the latter on the likelihood of the patient’s having unstable high-risk ischemia or MI without ECG changes. Despite advances in investigative modalities, a focused history and physical examination followed by an ECG remain the key tools for the diagnosis of MI. The most powerful features that increase the probability of MI, and their associated likelihood ratios (LRs), are new ST-segment elevation (LR range, 5.7-53.9); new Q wave (LR range, 5.3-24.8); chest pain radiating to both the left and right arm simultaneously (LR, 7.1); presence of a third heart sound (LR, 3.2); and hypotension (LR, 3.1). The most powerful features that decrease the probability of MI are a normal ECG result (LR range, 0.1-0.3), pleuritic chest pain (LR, 0.2), chest pain reproduced by palpation (LR range, 0.2-0.4), sharp or stabbing chest pain (LR, 0.3), and positional chest pain (LR, 0.3). Computer-derived algorithms that depend on clinical examination and ECG findings might improve the classification of patients according to the probability that an MI is causing their chest pain. JAMA. 1998;280:1256-1263

267 citations


Journal ArticleDOI
18 Feb 1998-JAMA
TL;DR: The attending physician on duty when a poor, 45-year-old man presents to the emergency department of a general hospital in the Philippines has severe chest pain for 2 hours, associated with clammy perspiration, and decides whether to offer this patient a thrombolytic agent.
Abstract: You are the attending physician on duty when a poor, 45-year-old man presents to the emergency department of a general hospital in the Philippines. He has severe chest pain for 2 hours, associated with clammy perspiration. Physical examination reveals a blood pressure of 110/70 mm Hg, a pulse rate of 92 beats per minute, a normal first heart sound, and clear lungs. An electrocardiogram discloses 3-mm ST-segment elevation in the inferior leads. As intravenous lines are placed, and the patient is prepared for admission to the coronary care department, you consider whether you should offer this patient a thrombolytic agent. Though your response is that the impecunious patient cannot afford the treatment, you ponder the right course of action in a richer patient. As your duty ends that night, you resolve to prepare forthenextpatientadmittedforanacute myocardial infarction (MI) by retrieving the best evidence on the use of thrombolytics.

229 citations


Journal ArticleDOI
TL;DR: A 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 as mentioned in this paper.
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

217 citations


Journal Article
TL;DR: A systematic review of randomized, controlled trials to assess the efficacy of HMGcoA reductase inhibitors compared with the efficacyof other cholesterol-lowering interventions to reduce the incidence of stroke found no reduction in stroke-related morbidity or mortality rates.
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 wit...

160 citations


Journal ArticleDOI
TL;DR: QOL assessments occur infrequently in the ICU literature and are of limited methodologic quality, so more studies using valid and reliable instruments are necessary to document the long-term QOL of critically ill patients, especially those at risk of a "poor" outcome.
Abstract: Objectives To present a framework for describing/measuring quality of life (QOL) and health-related quality of life (HRQL), and to assess the frequency and methodologic rigor of QOL studies in the adult critical care literature. Data sources Computerized bibliographic search of published research, manual search of key intensive care unit (ICU) journals, and citation review of relevant articles. Study selection We manually searched Critical Care Medicine, American Journal of Respiratory and Critical Care Medicine, and Intensive Care Medicine for the period January 1992 to July 1995 to assess the frequency of published QOL studies. Combined with a computerized bibliographic search, we found 64 studies that met our criteria that reported on patient-related outcomes (other than mortality) after hospital discharge. Data extraction We abstracted data on the nature of each study, the instruments used to measure QOL, and the methodologic rigor of the QOL assessments. We evaluated each study using criteria we developed to assess the validity of HRQL measurements. Measurements and main results In our manual search, we found 1,073 articles relevant to the practice of adult critical care. Of these, 19 (1.7%)/1073 included QOL measurements. Combined with our comprehensive search strategy, we found 64 papers that evaluated QOL in ICU patients. These papers dealt primarily with issues of: prognosis (32 [50%]), resource allocation (23 [36%]), and clinical prediction (9 [14%]). We found no randomized trials that included post-ICU QOL as an outcome. With respect to the validity of the HRQL assessments, 63/64 (98%) studies evaluated aspects of patients' lives that we considered important. Thirty-three (52%) studies were limited in scope to specific aspects of HRQL, and 31 (48%) studies covered broad areas of HRQL. In these 64 studies, there were 108 different instruments used. The reliability and validity of the instruments used were reported in 7 (6%) and 15 (14%) cases, respectively. For 81 (75%) instruments, the investigators either explained the results or used informative, qualitative descriptors whose interpretation was self-evident. Overall, three (5%) of the included studies met all four methodologic criteria to assess the validity of HRQL assessments. Conclusions QOL assessments occur infrequently in the ICU literature and are of limited methodologic quality. More studies using valid and reliable instruments are necessary to document the long-term QOL of critically ill patients, especially those at risk of a "poor" outcome.

135 citations


Journal ArticleDOI
TL;DR: Improved generic and specific HRQL was associated with poorer baseline HRQL and less baseline cardiovascular risk, which reinforces the importance of addressing health behavior changes as soon as possible after MI and the usefulness of assessing both generic and Specific HRQL in evaluating treatment effectiveness.
Abstract: Background Health-related quality of life (HRQL) instruments provide valid and responsive outcome measures to assess the impact of disease and the response to interventions. However, they have not been applied widely to studies of rehabilitation after myocardial infarction. Purpose To examine the extent to which baseline sociodemographic and clinical characteristics predict baseline and change in generic and specific HRQL. Methods A randomized controlled trial of an 8-week cardiac rehabilitation intervention or usual care, with follow-up for 12 months, in 201 patients with acute myocardial infarction (MI). Multiple regression analysis was used to identify predictors of HRQL. Results Specific HRQL scores and exercise tolerance improved significantly more in rehabilitation patients than usual care patients by the end of the 8-week intervention. All HRQL measures and exercise tolerance in both groups improved significantly during the 12 month follow-up period but the differences between the groups were trivial. A poor baseline HRQL was the predominant predictor of improved generic and specific HRQL. Furthermore, greater improvement in HRQL consistently was associated with lower levels of cardiovascular risks such as absence of a previous MI or coronary artery bypass surgery, absence of angina, less smoking, and higher exercise tolerance. Conclusions Improved generic and specific HRQL was associated with poorer baseline HRQL and less baseline cardiovascular risk. This reinforces the importance of addressing health behavior changes as soon as possible after MI and the usefulness of assessing both generic and specific HRQL in evaluating treatment effectiveness.

112 citations


Journal ArticleDOI
TL;DR: The Spanish translation of the Chronic Respiratory Questionnaire is likely to be useful for measuring differences between patients, and particularly for measuring the effects of intervention on quality of life in chronic respiratory disease.
Abstract: The aim of this study was to translate the Chronic Respiratory Questionnaire (CRQ) into Spanish and to test its measurement properties. The study was performed in 60 patients with chronic obstructive pulmonary disease (forced expiratory volume in one second (FEV1) mean+/-SD 35+/-14% of reference value). A rigorous process of forward and back translation and review produced an easily comprehensible questionnaire, which was administered together with measures of pulmonary function and exercise capacity. The patients were randomly allocated to one of two groups: 30 received respiratory rehabilitation and the other 30 received standard community care only. Weak to moderate statistically significant correlations (0.2-0.38) were found between the domains of the CRQ and pulmonary function and exercise measures. For the three CRQ domains that measure differences between patients at a point in time, Crohnbach's alpha and intraclass correlation coefficients were: fatigue 0.80 and 0.80; emotional function 0.86 and 0.68; and mastery domains 0.84 and 0.67, respectively. Scores remained stable in patients who were deemed clinically stable, and showed large statistically significant improvement (p<0.0001) in patients in the rehabilitation programme. Only low correlations were found between the changes in CRQ and the changes in pulmonary function and exercise capacity. The index of responsiveness was 0.92 for fatigue, and 0.91 for dyspnoea, emotional function and mastery. In conclusion, the Spanish translation of the Chronic Respiratory Questionnaire is likely to be useful for measuring differences between patients, and particularly for measuring the effects of intervention on quality of life in chronic respiratory disease.

Journal ArticleDOI
TL;DR: Your patient is a 60-year-old hypertensive, alcobolic woman whose symptomless atrial fibrillation was first documented 3 months aqo, and an echocardiogram shows an enlarged left atrium, rendering successful cardio-version unlikely.
Abstract: Your patient is a 60-year-old hypertensive, alcobolic woman whose symptomless atrial fibrillation was first documented 3 months aqo. An echocardiogram shows an enlarged left atrium, rendering successful cardio-version unlikely. She tells you that both of her parents bad severe strokes that made the lest years of their lives horrible, and she is terified of having a stroke. Yon know that a meta-analysis of 5 randomized trials of warfarin in nonvalvular atrial fibrillation demonstrated a 68% relative risk reduction (RRR) in stroke (I). You consider prescribing watfarin for this patient but know that she would not have qualified for the study because alcoholism increases her risk for major hemorrhage (2).

Journal ArticleDOI
11 Jul 1998-BMJ
TL;DR: Clinicians determine the day to day care patients receive in healthcare systems, and user groups are also beginning to play an important role in influencing healthcare decisions.
Abstract: This is the second in a series of eight articles analysing the gap between research and practice Series editors: Andrew Haines and Anna Donald There is increasing interest in providing evidence based health care—that is, care in which healthcare professionals, provider managers, those who commission health care, the public, and policymakers consistently consider research evidence when making decisions 1 2 Purchasers, for example, should be able to influence the organisation and delivery of care (such as for cancer3 and stroke services4) and the type and content of services (such as using chiropractic for back pain or dilatation and curettage and drug treatment for menorrhagia5) Policymakers should ensure that policies on treatment reflect and are consistent with research evidence, and that the incentive structure within the health system promotes cost effective practice They must also ensure that there is an adequate infrastructure for monitoring changes in practice and for producing, gathering, summarising, and disseminating evidence Clinicians determine the day to day care patients receive in healthcare systems, and user groups (for example, patients, their families, and their representatives) are also beginning to play an important role in influencing healthcare decisions6 The factors described below should be considered when deciding whether to act on or promote the implementation of research findings #### Summary points

Journal ArticleDOI
TL;DR: The potential for misinterpretation of outcome performance ratings may decrease if articles describing outcome differences are evaluated, using the criteria outlined in this article.
Abstract: Objectives: Comparisons of risk-adjusted outcomes among intensive care units (ICUs) is a relatively new but rapidly expanding area of ICU health services research. By investigating those factors that lead ICUs to have patient outcomes that differ from the average, the overall quality of care across ICUs may be improved. Our goal is to teach clinicians how to evaluate these types of articles. Clinical Example: An article describing the development and application of an index used to assess the clinical performance and cost-effectiveness of 25 ICUs. Recommendations: Valid comparisons of the outcomes among ICUs are made when: a) the outcome measures are accurate and comprehensive; b) the ICUs being compared serve similar patients ; c) the sampling of patients is sufficient and unbiased; d) appropriate risk adjustment is undertaken by applying a valid model to reliably collected data; and e) the comparisons focus on care delivered in the ICU. To evaluate the results of the study, clinicians must evaluate how confident they are that the outcome differences being described are clinically important. Before changes in ICU policy are made based on these outcome differences, it is important to clarify which factors might have resulted in these extreme outcomes and whether these results are applicable in the ICU population that will see the impact of the changes. Conclusion: The potential for misinterpretation of outcome performance ratings may decrease if articles describing outcome differences are evaluated, using the criteria outlined in this article.

Journal ArticleDOI
TL;DR: In this paper, the authors examined the relationship between intensive care unit (ICU) healthcare workers' confidence and their decision to withdraw life support and found that ICU workers chose the level of care (from comfort measures only).
Abstract: ObjectiveTo examine the relationship between intensive care unit (ICU) healthcare workers' confidence and their decision to withdraw life support.DesignCross-sectional survey of Canadian intensivists, ICU housestaff, and bedside nurses. Respondents chose the level of care (from comfort measures only


Journal ArticleDOI
TL;DR: In patients with non-small cell lung cancer, surgical resection margin or highest nodal station sampled at thoracotomy that are involved by carcinoma do not predict recurrence, and the current definition of incomplete resection has limited prognostic significance.

Journal ArticleDOI
TL;DR: The goal was to consolidate the best existing evidence from human clinical trials of immunosuppressive therapy in lymphocytic myocarditis and to address the limitations of the present knowledge.
Abstract: Background: The use of immunosuppressive therapy for myocarditis is controversial. Purpose: To review the literature on the effectiveness of immunosuppressive therapy in biopsy-proven lymphocytic m...

Journal ArticleDOI
TL;DR: Evidence-based clinicians consider not only the strength of evidence, but the patients' risk of adverse target outcomes and the magnitude of treatment effects in making their therapeutic decisions, and are aware that evidence never provides an adequate guide for treatment decisions when considered on its own.

Journal ArticleDOI
TL;DR: Identifying those factors inherent in clinical studies that positively impact the lives of osteoporotic patients should become as important a priority as development of new therapies for this chronic disease.
Abstract: Although osteoporosis affects millions of elderly women, the quality of their lives is extremely complex and is only recently being appreciated. We recently used a disease-specific Osteoporosis Quality of Life questionnaire (OQLQ) to measure quality of life for 105 elderly osteoporotic women, and reported that by path analysis, spinal fractures, health perception, and several sociodemographic factors accounted for 63% of the variance in quality of life. On the other hand, bone density, Colles fracture, hip fractures, pharmacologic agents, exercise, and several sociodemographic variables were not significant factors. Of particular note was the positive, indirect effect (via health perception and spinal fractures) that participation in a clinical trial (17.5% of the patients) had on life quality. In order to determine how involvement in a research study might affect health perception in this same cohort we examined OQLQ scores in the five domains of the OQLQ for the 18 postmenopausal osteoporotic women enrolled in two different phase III clinical trials with oral bisphosphonates and 87 osteoporotic women treated conventionally (estrogen, bisphosphonate, calcitonin, calcium/vitamin D) in our metabolic bone clinic. Research and clinical patients did not differ in age, femoral BMD, or number of spinal fractures. However, women in research trials had significantly greater aggregate OQLQ scores (5.67 versus 4.23, P < 0.0001) and perceived health (7.28 versus 5.85, P= 0.001) than clinical patients. These differences were highly significant (P < 0.001) for domains of quality of life including physical function, activities of daily living, symptoms, and leisure/social activity and marginally significant for the emotional function domain (P= 0.05). Hence, by regression-based path analysis and subgroup analysis of cross-sectional data, participation in a clinical trial had a significant and positive impact on health-related quality of life. If these findings are confirmed by other studies, identifying those factors inherent in clinical studies that positively impact the lives of osteoporotic patients should become as important a priority as development of new therapies for this chronic disease.




Journal ArticleDOI
TL;DR: The OQLQ is a validated disease-specific instrument developed to measure HRQL in women with spinal fracture caused by osteoporosis and future intervention studies should test nursing interventions to decrease the burden of suffering for women with this increasingly prevalent, chronic disease.
Abstract: Osteoporotic spinal fractures can be painful, debilitating, and contribute to impaired HRQL of elderly women. The OQLQ is a validated disease-specific instrument developed to measure HRQL in women with spinal fracture caused by osteoporosis. Future intervention studies should test nursing interventions to decrease the burden of suffering for women with this increasingly prevalent, chronic disease. Language: en



Journal ArticleDOI
TL;DR: To compare data produced with instruments used to obtain information from caregivers of demented older adults, when the instruments are self-administered at home or administered by an interviewer, three instruments were compared.
Abstract: Objective: To compare data produced with instruments used to obtain information from caregivers of demented older adults, when the instruments are self-administered at home or administered by an interviewer. Design: The functional status of patients with Alzheimer's disease was determined at baseline and six months later with three instruments using the patients' caregivers as informants. The instruments were both self-administered and administered by trained interviewers. Three other instruments were administered by interviewers only. Setting: A geriatric clinic in an urban university teaching hospital and residences of the patients. Participants: Thirty-four Alzheimer's patients and their caregivers completed the study. Measurements: Three instruments were compared: an activities of daily living instrument, a sleep problem instrument, and a dysfunctional behavior instrument. Validity was determined by Pearson correlations and agreement with intraclass correlations (ICC) on base-line assessments...