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Biomedical subjects

G Guyatt

Publications and source records attributed to G Guyatt.

At least 19 recordsLinked to original sources
PubMed1996

A new measure of parent satisfaction with medical care provided in the neonatal intensive care unit.

The objective of this study was to develop a valid and reliable discriminative index that measures parent satisfaction with the medical care of their infant in the NICU. We developed an initial questionnaire (Item Reduction Questionnaire) by reviewing the literature, surveying 63 NICU clinicians, and interviewing 125 parents of infants in 2 tertiary level NICUs regarding what they liked and disliked about the medical care of their infants. We administered the Item Reduction Questionnaire, which included 154 items, to 60 parents, who rated the frequency and importance of these items. We included the items identified most frequently as sources of dissatisfaction and rated most important in a second, briefer instrument, the Neonatal Index of Parent Satisfaction (NIPS). To measure reliability we administered the NIPS to 47 parents twice, separated by a 1-week interval. We assessed validity by comparing actual to predicted correlations between NIPS scores and other measures: parent's global rating of satisfaction, medical caregiver ratings of mother's satisfaction, medical caregiver ratings of father's satisfaction, and parents' perception of their infant's health status. We also compared mean NIPS scores for parents who did and who did not report incidents when errors occurred in the medical care of the infant. Of 154 items generated, we included 27 in the NIPS. The intraclass correlation between two administrations of the NIPS to the same 47 parents was 0.71. As predicted, there was a high correlation (0.61) between the NIPS score and parent global rating of satisfaction, and much lower correlations with other variables. Mean NIPS scores for parents who did and who did not report errors differed significantly (difference, 14.6; 95% CI around difference, 5.8-23.5; p < 0.001). The NIPS is likely to be a useful measure for discriminating between parents who differ in terms of their satisfaction with the medical care of their infant in the NICU.

Adult↗
PubMed1995

Basic statistics for clinicians: 4. Correlation and regression.

Correlation and regression help us to understand the relation between variables and to predict patients' status in regard to a particular variable of interest. Correlation examines the strength of the relation between two variables, neither of which is considered the variable one is trying to predict (the target variable). Regression analysis examines the ability of one or more factors, called independent variables, to predict a patient's status in regard to the target or dependent variable. Independent and dependent variables may be continuous (taking a wide range of values) or binary (dichotomous, yielding yes-or-no results). Regression models can be used to construct clinical prediction rules that help to guide clinical decisions. In considering regression and correlation, clinicians should pay more attention to the magnitude of the correlation or the predictive power of the regression than to whether the relation is statistically significant.

Data Interpretation, Statistical↗
PubMed1995

Basic statistics for clinicians: 3. Assessing the effects of treatment: measures of association.

In the third of a series of four articles the authors show the calculation of measures of association and discuss their usefulness in clinical decision making. From the rates of death or other "events" in experimental and control groups in a clinical trial, we can calculate the relative risk (RR) of the event after the experimental treatment, expressed as a percentage of the risk without such treatment. The absolute risk reduction (ARR) is the difference in the risk of an event between the groups. The relative risk reduction is the percentage of the baseline risk (the risk of an event in the control patients) removed as a result of therapy. The odds ratio (OR), which is the measure of choice in case-control studies, gives the ratio of the odds of an event in the experimental group to those in the control group. The OR and the RR provide limited information in reporting the results of prospective trials because they do not reflect changes in the baseline risk. The ARR and the number needed to treat, which tells the clinician how many patients need to be treated to prevent one event, reflect both the baseline risk and the relative risk reduction. If the timing of events is important--to determine whether treatment extends life, for example--survival curves are used to show when events occur over time.

Case-Control Studies↗
PubMed1995

Basic statistics for clinicians: 2. Interpreting study results: confidence intervals.

In the second of four articles, the authors discuss the "estimation" approach to interpreting study results. Whereas, in hypothesis testing, study results lead the reader to reject or accept a null hypothesis, in estimation the reader can assess whether a result is strong or weak, definitive or not. A confidence interval, based on the observed result and the size of the sample, is calculated. It provides a range of probabilities within which the true probability would lie 95% or 90% of the time, depending on the precision desired. It also provides a way of determining whether the sample is large enough to make the trial definitive. If the lower boundary of a confidence interval is above the threshold considered clinically significant, then the trial is positive and definitive, if the lower boundary is somewhat below the threshold, the trial is positive, but studies with larger samples are needed. Similarly, if the upper boundary of a confidence interval is below the threshold considered significant, the trial is negative and definitive. However, a negative result with a confidence interval that crosses the threshold means that trials with larger samples are needed to make a definitive determination of clinical importance.

Clinical Trials as Topic↗
PubMed1995

Basic statistics for clinicians: 1. Hypothesis testing.

In the first of a series of four articles the authors explain the statistical concepts of hypothesis testing and p values. In many clinical trials investigators test a null hypothesis that there is no difference between a new treatment and a placebo or between two treatments. The result of a single experiment will almost always show some difference between the experimental and the control groups. Is the difference due to chance, or is it large enough to reject the null hypothesis and conclude that there is a true difference in treatment effects? Statistical tests yield a p value: the probability that the experiment would show a difference as great or greater than that observed if the null hypothesis were true. By convention, p values of less than 0.05 are considered statistically significant, and investigators conclude that there is a real difference. However, the smaller the sample size, the greater the chance of erroneously concluding that the experimental treatment does not differ from the control--in statistical terms, the power of the test may be inadequate. Tests of several outcomes from one set of data may lead to an erroneous conclusion that an outcome is significant if the joint probability of the outcomes is not taken into account. Hypothesis testing has limitations, which will be discussed in the next article in the series.

Clinical Trials as Topic↗
PubMed1995

[The Spanish translation and evaluation of a quality-of-life questionnaire in patients with chronic obstructive pulmonary disease].

The Chronic Respiratory Disease Questionnaire (CRDQ), proposed by Guyatt et al, is a specific instrument used to assess quality of life in patients with chronic obstructive pulmonary disease (COPD). Our aim was to translate the questionnaire and validate it so that it could then be used as a measurement instrument in programs of respiratory rehabilitation. Sixty-five patients with COPD who were candidates for breathing therapy were enrolled in the study. Mean age was 64 +/- 7 years and all had severe air flow limitation, with FEV1 33 +/- 13% over reference values but not respiratory failure (pO2 70 +/- 10 mmHg). The questionnaire was subjected to a process of translation/back translation and disagreements over wording were discussed by a panel of bilingual speakers and the author himself. The validation process involved the following steps: 1) a comprehension study with a group of 5 patients, which revealed no special difficulties; 2) analysis of internal consistency or reliability by way of Crombach's alpha coefficient, which gave and overall score of 0.92 and area scores of 0.51 for dyspnea, 0.8 for fatigue, 0.86 for emotional factors and 0.84 for disease control, and 3) analysis of correlation between various lung function parameters and exercise test results (6 min of increasing effort and a stationary cycle), which showed weak but statistically significant correlations that were comparable to those found by the author of the original CRDQ.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

Enteral nutrition in the critically ill patient: a prospective survey.

OBJECTIVES: To describe current enteral nutrition-prescribing practices for critically ill patients, and to identify factors associated with initiation of, and tolerance to, enteral nutrition. DESIGN: A prospective, cohort study. SETTING: Two tertiary care medical-surgical intensive care units (ICU) in Ontario, Canada. PATIENTS: We enrolled 99 consecutive patients who were expected to stay in the ICU for > 3 days and who were unable to tolerate oral nutrition. We followed patients for 21 days or until they tolerated enteral nutrition, tolerated oral nutrition, were discharged from the ICU, or died. MEASUREMENTS AND MAIN RESULTS: We recorded time elapsed from ICU admission to initiation and tolerance of enteral feedings, and examined factors associated with these events. We defined tolerance as receiving 90% of estimated daily energy requirements for > 48 hrs without gastrointestinal dysfunction (i.e., high gastric residuals, vomiting, diarrhea, abdominal distention). Seventy-three (74%) of 99 patients were started on enteral feedings an average 3.1 days (range 1 to 18) after ICU admission. Of 26 patients never started on enteral nutrition, three (12.5%) patients eventually tolerated oral nutrition, 14 (54.0%) patients were discharged from the ICU, and seven (27.0%) patients died. Reasons for not initiating enteral nutrition included absence of bowel sounds (27.0%), high nasogastric drainage (16.9%), contraindication to enteral nutrition (16.7%), tolerance of oral nutrition (6.8%), and no apparent reason (5.1%). Abdominal surgery, use of vasoactive drugs, and admission to one hospital made initiation of enteral nutrition less likely, whereas presence of bowel sounds and admission to the other hospital made initiation of enteral nutrition more likely. Thirty-five (42.9%) of 73 patients started on enteral nutrition achieved tolerance of the regimen. The average time from ICU admission to tolerance of feedings was 5.8 days (range 1 to 14). Once started on enteral nutrition, the most common reasons for decreasing or discontinuing feedings included high gastric residuals (51.0%), mechanical feeding tube problems (15.4%), medical or surgical procedures (5.4%), and vomiting (5.1%). Use of paralytic agents and the presence of high gastric residuals were associated with intolerance. Of 38 patients who did not achieve tolerance, 20 (52.6%) patients were discharged from the ICU, eight (21.0%) patients died, and eight (21.0%) patients eventually tolerated oral nutrition. CONCLUSIONS: Enteral nutrition is not started in all eligible ICU patients. Approximately half of those patients receiving enteral nutrition achieved tolerance of the regimen. Gastrointestinal dysfunction causing intolerance to enteral nutrition is a common reason for not starting, or discontinuing, feedings.

Critical Illness↗
PubMed1995

Profile of mood states and cardiac rehabilitation after acute myocardial infarction.

Following an acute myocardial infarction, evaluation of a patient's own perceptions of health, including mood state, provides useful information about the efficacy of rehabilitation when data are available for patients randomized to both control and intervention. Data are presented on the Profile of Mood States (POMS) in 187 patients, with mild to moderate scores for Spielberger state anxiety and/or Beck depression, who were randomized within 6 wk of acute myocardial infarction to usual care or to brief cardiac rehabilitation lasting 8 wk and who were followed-up during the 12 months following the acute event. Repeated measures multivariate analysis of covariance identified significant main as well as time effects in POMS scores over 12 months. Repeated measures analysis of variance over the 12 months demonstrated significant improvement for both depression and anxiety in both groups. At 8 wk, improvement was greater in the rehabilitation patients than usual care patients but only in the tension-anxiety, depression-dejection and vigor-activity dimensions of POMS and only in anxiety in those patients with above mean anxiety scores. Overall, rehabilitation and control patients showed similar and significant improvements in anxiety, depression and in mood states over the duration of the 12-month trial.

Adult↗
PubMed1994

Intellectual property considerations in the development and use of HRQL measures for clinical trial research.

As a result of the expanded use of health-related quality of life (HRQL) measures in clinical trial research, a variety of legal and ethical issues have surfaced. These issues can be put in the form of the following questions: (1) Under what circumstances should access to HRQL measures be restricted? (2) Under what circumstances is it appropriate for the developers of HRQL measures to assert their intellectual property rights to the instruments? (3) Under what circumstances is personal profit from the sale and use of HRQL measures legally and socially appropriate? Access to HRQL research is to be encouraged since this is necessary for this field to progress. However, the need for protection against misuse of ongoing work is real and may justify the assertion of intellectual property rights. HRQL measures developed entirely with public monies should remain in the public domain or be managed for the public good. Instruments developed with private funds or with a mix of public and private funds should be treated in a manner that reflects a fair balance between the rights of the private developer and those of the scientific community and the public. HRQL questionnaires are regularly being refined; such work is costly. Investigators continuing research directly related to instrument refinement might reasonably ask for compensation from those who wish to use their work.

Clinical Trials as Topic↗
PubMed1994

Spectrum of quality of life impairment in hypothyroidism.

The aim of this study is to evaluate the frequency and relative importance of different aspects of health related quality of life (HRQOL) impairment in patients with hypothyroidism. A survey of 200 patients with treated hypothyroidism was undertaken. Patients were identified and questionnaires distributed through family physicians, endocrinologists, and regional branches of the Thyroid Foundation of Canada. Frequency of importance of patients' symptoms attributed to hypothyroidism and resolved or improved with treatment were measured. Establishing the wide variety of patient-specific complaints associated with hypothyroidism provides guidance for clinicians dealing with hypothyroid patients, and investigators interested in HRQOL impairment in these patients.

Humans↗
PubMed1994

The core content of a generalist curriculum for general internal medicine, family practice, and pediatrics.

The authors analyzed the educational content of the curricula developed for teaching in the generalist disciplines of pediatrics, family medicine, and general internal medicine. Fifteen educational components that constitute the core content shared by the three generalist disciplines are identified, described, and referenced. Tailoring the generalist curriculum for students and residents at the different stages of learning is reviewed, along with the refinement of the curriculum to meet the special needs of each generalist discipline. The success of a generalist curriculum will ultimately be measured by generalist career choices, quality of care, and both patient and professional satisfaction. The curricular determinants of success require institutional commitment to an educational philosophy that embraces the generalist disciplines, a core curriculum that provides education and training that are correlated with the demands of clinical practice, and generalist faculty who serve as role models, mentors, and teachers.

Adult↗
PubMed1993

Economic evaluation of cardiac rehabilitation soon after acute myocardial infarction.

Although there are extensive clinical evaluations of cardiac rehabilitation after acute myocardial infarction (AMI), no full economic evaluation is available. Patients with AMI and mild to moderate anxiety or depression, or both, while still in hospital were randomized to either an 8-week rehabilitation intervention (n = 99) or usual care (n = 102). Comprehensive costs and health-related quality of life, measured with the time trade-off preference score, were obtained in a 12-month trial, and together with survival data derived from published meta-analyses, cost-utility and cost-effectiveness of early cardiac rehabilitation were estimated. The best estimate of the incremental net direct 12-month costs for patients randomized to rehabilitation was $480 (United States, 1991)/patient. During 1-year follow-up, rehabilitation patients had fewer "other rehabilitation visits" (p < 0.0001) and gained 0.052 quality-adjusted life-year more than did the group with usual care. The cost-utility ratio was $9,200/quality-adjusted life-year gained with cardiac rehabilitation during the year of follow-up. This economic evaluation of cardiac rehabilitation does not consider the important distinctions between affordability and worth of alternative health-care services. The data provide evidence that brief cardiac rehabilitation initiated soon after AMI for patients with mild to moderate anxiety or depression, or both, is an efficient use of health-care resources and may be economically justified.

Canada↗
PubMed1993

A proposal for enhancing the quality of clinical teaching: results of a department of medicine's educational retreat.

New challenges for clinical teachers include incorporating a deeper appreciation of the use of the published literature in day-to-day practice and teaching, responding to the profusion of diagnostic tests and treatments, and dealing with changing practical difficulties. We report a summary of a retreat conducted by our Department of Medicine in which our faculty presented and refined strategies they had developed to deal with these challenges. Areas of discussion include developing an effective medical team managing time on a busy clinical service, teaching pathophysiology, teaching clinical skills, and teaching critical appraisal. Our observations are likely to be useful to clinicians involved in patient-centred teaching in wards and clinics, particularly those interacting with groups of undergraduate and post-graduate trainees.

Clinical Clerkship↗