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Biomedical subjects

G Guyatt

Publications and source records attributed to G Guyatt.

At least 91 records · Page 5Linked to original sources
PubMed1992

A research method to induce and examine a mild exacerbation of asthma by withdrawal of inhaled corticosteroid.

This study evaluated a research method to examine an exacerbation of asthma induced by corticosteroid withdrawal. Ten non-smoking adult asthmatics who were stable on treatment with inhaled steroid underwent a graded reduction of the daily dose by 200 micrograms at weekly intervals until an exacerbation of symptoms occurred. A daily symptom, peak expiratory flow rate (PEF) and medication diary was kept. Weekly clinic visits were used to assess symptoms, spirometry, methacholine airway responsiveness (expressed as the provocative concentration to cause a fall in FEV1 of 20%, PC20), circulating eosinophils, basophils and their progenitors (Eo/B-CFU), and sputum inflammatory cells. The laboratory tests were performed blind to the clinical details. Each subject developed an exacerbation of symptoms, on average at 16 (7-26) days after the onset of steroid reduction. This was accompanied by a deterioration in each of the objective measures. There was a fall in FEV1 by 320 ml (s.e.m. 9.5) and in PC20 from 0.8 to 0.43 mg/ml. Circulating eosinophils rose from 114 (24) x 10(3)/ml to 227 (50) x 10(3)/ml and Eo/B-CFU rose from 31 (5.6) to 44 (11.3)/10(6) cells. Sputum developed in five subjects and contained 36 (5.2)% eosinophils and 1.98 (0.21)% metachromatic cells (mast cells or basophils). The symptom diary and weekly questionnaire were demonstrated to be valid and responsive to change. A deterioration indicated by the daily symptom score preceded changes in PEF. Treatment by an increase in steroid was followed by reversal of each of the changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗
PubMed1992

Controlled trial of respiratory muscle training in chronic airflow limitation.

BACKGROUND: Whether respiratory muscle training is of benefit to patients with chronic airflow limitation is controversial. The objective of the study was to determine the effect of resistance breathing training on physiological and functional measures in patients with chronic airflow obstruction. METHODS: The design was a randomised, double blind, controlled trial with a six month follow up. Eighty two patients with a forced expiratory volume in one second (FEV1) of less than 70% predicted, and an FEV1/vital capacity ratio of less than 0.7, were randomised to receive training for 10 minutes five times daily with progressively larger resistances through a resistive breathing device (PFLEX) as tolerated or to a sham device which gave minimal resistance. The main outcome measures, respiratory muscle strength and endurance, a progressive exercise test, a six minute walk test and physical and emotional function (chronic respiratory questionnaire) were assessed at monthly intervals. Patients in both groups were also randomised to wear or not wear nose clips during their training. RESULTS: No significant differences were observed between treatment and control groups, with or without nose clips, for any of the outcomes. Confidence intervals on the difference between treatments were narrow, excluding clinically important difference in any major outcome. CONCLUSION: This training regimen fails to strengthen respiratory muscles or improve exercise or functional capacity in patients with chronic airflow limitation.

Aged↗
PubMed1992

The protective effect of vitamin E on the hemolysis associated with dapsone treatment in patients with dermatitis herpetiformis.

OBJECTIVE: This study looked at whether oral vitamin C and vitamin E would protect the erythrocyte from oxidant damage caused by dapsone in patients with dermatitis herpetiformis. DESIGN: Fifteen consecutive patients with dermatitis herpetiformis taking dapsone therapy received, in addition, 800 U/d of vitamin E for 4 weeks; then 1000 mg of vitamin C per day for 4 weeks, and, finally, combined vitamin E and vitamin C therapy for 4 weeks. Hemolysis indexes were assessed at baseline and after each 4-week period. RESULTS: Statistical analysis of the results suggests that oral administration of 800 units of vitamin E daily for 4 weeks confers partial protective effect against dapsone-induced hemolysis in patients with dermatitis herpetiformis. CONCLUSION: Partial protection against dapsone-induced hemolysis by orally administered vitamin E, if confirmed as being clinically relevant by further trials, may allow clinicians to continue dapsone therapy orally in patients who develop significant hemolysis. Prophylactic vitamin E to minimize potential hemolysis at the initiation of dapsone therapy may also be appropriate.

Adult↗
PubMed1991

Effects on quality of life with comprehensive rehabilitation after acute myocardial infarction.

This investigation was designed to determine the impact of a brief period of cardiac rehabilitation, initiated within 6 weeks of acute myocardial infarction (AMI), on both disease-specific and generic health-related quality of life, exercise tolerance and return to work after AMI. With a stratified, parallel group design, 201 low-risk patients with evidence of depression or anxiety, or both, after AMI, were randomized to either an 8-week program of exercise conditioning and behavioral counseling or to conventional care. Although the differences were small, significantly greater improvement was seen in rehabilitation group patients at 8 weeks in the emotions dimension of a new disease-specific, health-related Quality of Life Questionnaire, in their state of anxiety and in exercise tolerance. All measures of health-related quality of life in both groups improved significantly over the 12-month follow-up period. However, the 95% confidence intervals around differences between groups at the 12-month follow-up effectively excluded sustained, clinically important benefits of rehabilitation in disease-specific (limitations, -2.70, 1.40; emotions, -4.86, 1.10, where negative values favor conventional care and positive values favor rehabilitation) and generic health-related quality of life (time trade-off, -0.062, 0.052; quality of well-being, -0.042, 0.035) or in exercise tolerance (-38.5, 52.1 kpm/min); also, return to work was similar in the 2 groups (relative risk, 0.93; confidence interval, 0.71, 1.64).(ABSTRACT TRUNCATED AT 250 WORDS)

Anxiety↗
PubMed1991

Clinical significance of primitive reflexes in Alzheimer's disease.

STUDY OBJECTIVE: To establish the relationship between cognition, behavior, function, and clinical characteristics on the one hand, and the presence of primitive reflexes (PR) (pout, snout, palmomental and grasp) in patients with Alzheimer's disease (AD). DESIGN: Cross-sectional survey. SETTING: Secondary care geriatric practice specializing in the assessment of cognitive impairment. SUBJECTS: 136 consecutive patients presenting with AD. MEASUREMENTS: PR were assessed in standardized fashion by a single clinician. Cognitive function was measured using the Standardized Mini-Mental Status Examination, activities of daily living (ADL) and instrumental activities of daily living (IADL) were measured using the Lawton scale, and behavior was measured using the Behavioural Problem Checklist. RESULTS: There was no difference in age or duration of dementia in those with and without PR, nor was there any difference in cognitive function. Despite this, patients with PR showed a greater degree of functional limitation and dysfunctional behavior. There was also a higher incidence of rigidity, gait abnormalities, and apraxia in patients with PR. CONCLUSIONS: Patients with primitive reflexes had more severe impairment in ADL function and dysfunctional behavior for an equal level of cognitive function.

Activities of Daily Living↗
PubMed1991

Clinical usefulness of amitriptyline in fibromyalgia: the results of 23 N-of-1 randomized controlled trials.

Twenty-three double blind, randomized, multiple crossover trials (N-of-1 RCT) of amitriptyline were conducted in patients with fibromyalgia. The benefit of amitriptyline was assessed using a symptom questionnaire and count of tender points. To assess the usefulness of the method, the proportion of trials that provided a definite answer was examined. Completing the trial resulted in reaching a high degree of confidence in the final management decision in 74% of trials. In 35% of trials, results led to discontinuation of the drug which otherwise would have been continued indefinitely. The drug benefit, if present, was evident within first 2 weeks of therapy. We concluded that these results support the feasibility and usefulness of N-of-1 RCT in rheumatology practice.

Adult↗
PubMed1989

A new measure of health status for clinical trials in inflammatory bowel disease.

We have developed a measure of subjective health status (quality of life) for patients with inflammatory bowel disease (IBD). Ninety-seven patients with IBD described problems they had experienced as a result of the disease; the 32 most frequent and important items were included in the Inflammatory Bowel Disease Questionnaire (IBDQ). Sixty-one IBD patients were evaluated twice. One month separated the evaluations, at which disease activity indices, the IBDQ, and a number of other questionnaires were administered. Reproducibility studies in 19 stable patients showed improvement in scores, but also a small within-person standard deviation. Responsiveness studies revealed large changes in scores in patients who had improved or deteriorated and suggested that the IBDQ was more responsive than a general health status measure. Responsiveness appeared greater in patients with ulcerative colitis than in those with Crohn's disease. Predicted and observed correlations between changes in IBDQ score and changes in other measures were similar. We conclude that although further testing is required, particularly in examining the relation between changes in the IBDQ and changes in the activity of Crohn's disease, the IBDQ shows promise as a measure of health status for clinical trials in IBD.

Attitude to Health↗
PubMed1988

A clinician's guide for conducting randomized trials in individual patients.

In determining optimal treatment for a patient conventional trials of therapy are susceptible to bias. Large-scale randomized trials can provide only a partial guide and have not been or cannot be carried out for most clinical disorders. However, randomized controlled trials (RCTs) in individual patients (N of 1 RCTs) may in some circumstances provide a solution to this dilemma. In an N of 1 RCT a patient undergoes pairs of treatment periods (one period of each pair with the active drug and one with matched placebo, assigned at random); both the patient and the clinician are blind to allocation, and treatment targets are monitored. N of 1 RCTs are useful for chronic, stable conditions for which the proposed treatment, which has a rapid onset of action and ceases to act soon after it is discontinued, has shown promise in an open trial of therapy. The monitoring of treatment targets usually includes quantitative measurement of the patient's symptoms with the use of simple patient diaries or questionnaires. Pairs of treatment periods are continued until effectiveness is proved or refuted. The cooperation of a pharmacy is required for the preparation of matching placebos and conduct of the trial. Formal statistical analysis may be helpful for interpreting the results. The practical approach presented in this paper allows clinicians to conduct their own N of 1 RCTs.

Clinical Trials as Topic↗
PubMed1988

Quality of life in patients with inflammatory bowel disease.

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.

Adult↗
PubMed1988

Measuring health status in chronic airflow limitation.

A health status instrument for use in clinical trials must be valid (measuring what it is supposed to measure) and responsive (able to detect clinically important change). Approaches to measuring health status in clinical trials include using a battery of instruments, a general instrument which provides a profile of the patient's health, an instrument that generates a health utility, or an instrument that focuses on the problems associated with a particular disease. Disease-specific instruments have been used in clinical trials in chronic airflow limitation (CAL). The Oxygen Cost Diagram is simple and easy to administer, but responsiveness and validity are unproven. The Transition Dyspnoea Index is valid and responsive, but is difficult to use in trials in which multiple measurements are desired. The Chronic Respiratory Disease Questionnaire has proved valid and responsive in controlled trials in CAL patients. Health status measures should be included in all clinical trials in CAL.

Attitude to Health↗
PubMed1987

Measuring change over time: assessing the usefulness of evaluative instruments.

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 in which items are tailored to the individual respondent. Therefore, we suggest a new index of responsiveness to assess the usefulness of instruments designed to measure change over time. This statistic, which relates the minimal clinically important difference to the variability in stable subjects, has direct sample size implications. Responsiveness should join reliability and validity as necessary requirements for instruments designed primarily to measure change over time.

Humans↗
PubMed1987

Treatment of cryptosporidiosis with spiramycin in AIDS. An "N of 1" trial.

We describe a randomized, double-blind, placebo-controlled, crossover trial with spiramycin in a single patient with acquired immune deficiency syndrome (AIDS) and a severe secretory diarrhea caused by cryptosporidium. Spiramycin, a potentially harmful antibiotic, had no clinical or microbiological effect in this patient. The application of the single patient (N of 1) trial to common clinical problems is a simple way to analyze the value of different therapeutic approaches. The time-consuming, expensive, multi-patient trial with ultimate extrapolation to the individual patient can be avoided. Single-patient trials can influence management and improve patient care and have potentially wide use in patients with gastrointestinal disease.

Acquired Immunodeficiency Syndrome↗