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Biomedical subjects

R Jaeschke

Publications and source records attributed to R Jaeschke.

At least 37 records · Page 2Linked to original sources
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

Effect of increasing doses of beta agonists on spirometric parameters, exercise capacity, and quality of life in patients with chronic airflow limitation.

BACKGROUND: A study was undertaken to determine the impact of different doses of inhaled terbutaline on peak flow rates, spirometric parameters, functional exercise capacity, and quality of life in patients with chronic airflow limitation. METHODS: A double blind, randomised, placebo controlled, multiple crossover trial was conducted with treatment periods of one week. Patients with a clinical diagnosis of chronic airflow limitation and FEV1 below 70% predicted after administration of bronchodilator were recruited from secondary care respiratory practices, and the effect of 500, 1000, and 1500 micrograms inhaled terbutaline four times daily on spirometric parameters (FEV1, FVC), maximum inspiratory pressures, six minute walking distance, and health-related quality of life (Chronic Respiratory Disease Questionnaire, Quality of Well Being, Standard Gamble) was measured. RESULTS: Twenty five patients completed the trial. Peak flow rates and FEV1 showed statistically significant but clinically trivial improvement on the higher drug doses. Results of maximum inspiratory pressure measurements, walk test distance, and quality of life measures showed minimal differences on the different dosages, and none of the differences approached conventional statistical significance. CONCLUSIONS: Regular use of beta agonists in doses higher than two puffs four times a day is very unlikely to provide additional functional or symptomatic benefit to patients with chronic airflow limitation.

Aged↗
PubMed1993

Interviewer versus self-administered questionnaires in developing a disease-specific, health-related quality of life instrument for asthma.

We wished to determine the extent to which respondents provided the same answers to a health-related quality of life (HRQL) questionnaire in self- and interviewer-administered forms. One hundred and fifty patients with asthma who were symptomatic or required treatment at least once a week, and had airway hyperresponsiveness to methacholine aerosol (PC20 < 8.0 mg/ml) participated. Patients completed a 152-item HRQL questionnaire in both interviewer and self-administered forms, separated by a 2-week interval, the order determined by random allocation. The percentage of items endorsed by the self-administered approach was significantly higher than that of the interviewer-administered approach overall (46.9 vs 35.8%) (p < 0.0001). The difference was consistent across all six domains; the absolute difference in the proportion of items endorsed varied from 8.9 to 12.3%. The intraclass correlations for the proportion of subjects endorsing an item was 0.84. Self- and interviewer-administered questionnaires yield very similar results in discriminating between subjects, but the self-administered version shows systematically greater HRQL impairment.

Adult↗
PubMed1993

An index of scientific quality for health reports in the lay press.

Although the quality of health reporting has been criticized for being unscientific, evaluations of health care reporting have been limited by the lack of a reliable and credible measure of scientific quality. We developed an index of scientific quality (ISQ) for health-related news reports and tested its reliability and sensibility. Items were generated from a survey of the literature and experts in research methodology. Items that were unclear, confusing or discriminated poorly between articles of high and low scientific quality were revised or deleted in an iterative process wherein potential criteria were independently applied to samples of 5 to 15 articles by 6 raters. To test the reliability of the final criteria 60 articles were drawn from three sampling frames: newspapers, magazines, and professional journals. Articles were intentionally selected to obtain a wide range of quality and topics. Two categories of raters were used: research assistants and physicians with research training. All 6 raters assessed all 60 articles. The sensibility of the index was tested by a questionnaire with 13 items related to face validity and content validity as well as other aspects of sensibility. The questionnaire was completed by 20 researchers and 13 health and science writers. The final ISQ includes 7 items that address the extent to which a report allows readers to draw conclusions about the applicability, validity and practical importance of the information that is reported. Chance corrected agreement (kappa) among all 6 raters for overall scientific quality was 0.62 (SE 0.02). The index was found to be sensible with only one major problem, the need for judgment in making ratings. While some degree of subjectivity appears to be inevitable in rating the scientific quality of health reports, the ISQ is acceptable reliable and credible and should be useful for evaluating and improving the scientific quality of health reporting.

Evaluation Studies as Topic↗
PubMed1993

The effect of increasing doses of beta-agonists on airflow in patients with chronic airflow limitation.

OBJECTIVE: To determine the increase in FEV1 associated with increasing doses of inhaled terbutaline and salbutamol, the reproducibility of the increase in FEV1, and the reproducibility of the associated optimal bronchodilator dose, in patients with chronic airflow limitation (CAL). DESIGN: Double-blind, randomized, controlled trial examining spirometric response to cumulative doses of bronchodilators. PATIENTS AND SETTING: Patients with clinical diagnosis of CAL, FEV1 below 70% predicted, and FEV1 to FVC ratio less than 0.7 after administration of bronchodilator recruited from secondary care respirology practices. MEASURES OF OUTCOME: The estimates of maximum and optimal bronchodilation, as well as the associated drug dosages, were established in each patient on three occasions (twice on terbutaline and once on salbutamol). The 'optimal' drug dose was defined as the lowest dose associated with an FEV1 not exceeded by 50 ml on any other dose. MAIN RESULTS: Thirty-five patients completed the trial. FEV1 improved from 0.93 to a maximum of 1.191 with terbutaline (average of the two administrations) and from 0.951 to 1.141 with inhaled salbutamol (difference in increase in FEV1 between terbutaline and salbutamol P = 0.006). In less than 50% of cases administration of more than four puffs of bronchodilator resulted in FEV1 increase by more than 50 ml. The average dose of salbutamol and terbutaline associated with optimal bronchodilation were 430 micrograms and 1160 micrograms respectively. Patients varied widely in the optimal dose. Estimates of optimal dose were not reproducible (intraclass correlation coefficient < 0.5). CONCLUSION: Substantial incremental increase in FEV1 in response to increasing doses of beta-agonists beyond those commonly used in clinical practice is restricted to a minority of patients. Lack of reproducibility limits the clinical usefulness of establishing the optimal dose of beta-agonist for a given patient.

Administration, Inhalation↗
PubMed1993

The relevance of detecting carotid artery calcification on plain radiograph.

BACKGROUND AND PURPOSE: The aim of this study was to determine the potential value of carotid artery calcification observed on plain radiographs in patients referred for carotid angiogram in the diagnosis of carotid artery stenosis. METHODS: One hundred sixty consecutive patients with suspected carotid artery stenosis underwent both plain radiographs of the carotid arteries and digital subtraction angiography of the same vessels. In addition, 108 of these patients also had duplex ultrasound of the same vascular area. The clinical usefulness of the carotid artery calcification was assessed by calculating the likelihood ratios for different test results against results of angiography and duplex ultrasound. RESULTS: There is a statistically significant association between the degrees of calcification and carotid disease as demonstrated by angiography (P = .0001), although positive correlations of the degrees of stenosis and calcification was only fair (Spearman correlation coefficient r = .4). The sensitivity of carotid calcification in detecting clinically significant stenosis assuming any calcification is abnormal was 89% with a specificity of 46%. The likelihood ratios for 50% stenosis by angiography varied from 0.24 (no calcification) to 3.41 (level III) and for 50% stenosis by duplex ultrasound varied from 0.21 (no calcification) to more than 5.87 (level III). Assessments of the degree of calcification based on plain radiographs had excellent reproducibility (all intraclass correlation coefficients were greater than .9). CONCLUSIONS: In this population with a high prevalence of carotid artery disease, there is an association between the presence of carotid calcification and atheromatous disease. If subsequent studies were to show this to apply in the general population, this could be of value in identifying asymptomatic patients at increased risk.

Aged↗
PubMed1992

Measuring health status: what are the necessary measurement properties?

The different measurement properties necessary for instruments whose goal is to detect differences between subjects at a single point in time (discriminative instruments) and those whose goal is to detect longitudinal change within subjects (evaluative instruments) is becoming increasingly recognized. Up to now, requirements for evaluative instruments have been presented as reproducibility, validity, and responsiveness (i.e. the ability to detect change over time). An alternative conceptualization would characterize any instrument as requiring two crucial measurement properties. One is validity, the other a high ratio of signal to noise. For discriminative instruments, the signal to noise ratio can be summarized in a reliability coefficient; for evaluative instruments, in a responsiveness index or coefficient. This formulation can simplify and clarify the understanding and teaching of issues in health status measurement.

Epidemiologic Methods↗
PubMed1992

Evaluation of impairment of health related quality of life in asthma: development of a questionnaire for use in clinical trials.

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 for measuring quality of life in clinical trials in asthma. METHODS: Impairment of quality of life in adults with asthma was evaluated from structured interviews in which patients were asked to identify the parts of their daily lives affected by asthma. On the basis of these results, an asthma quality of life questionnaire was developed in an interviewer and self administered form and tested for comprehension and acceptability. A total of 150 adults with asthma and with a wide range of airway hyperresponsiveness were enrolled from previous clinical trials, local asthma clinics, and notices in the media. RESULTS: Areas of quality of life impairment included symptoms classically associated with asthma, responses to environmental stimuli, the need to avoid these stimuli, limitation of activities, and emotional dysfunction. Areas of impairment were similar across strata of airway hyperresponsiveness, age, and treatment requirements and between sexes, thus allowing a single questionnaire suitable for all adults with asthma to be developed. The questionnaire contains 32 items and takes 5-10 minutes to administer; in the pretesting it was shown to be acceptable to a wide range of patients. CONCLUSIONS: The questionnaire includes areas of quality of life impairment that are important to adult asthmatic patients. It has been designed to be responsive to within subject change and therefore may be used as a measure of outcome in clinical trials in asthma.

Adolescent↗
PubMed1992

Quality of life instruments in the evaluation of new drugs.

The importance of measuring changes in a patient's quality of life when evaluating the efficacy of new drugs is increasingly recognised. In this paper, we review the steps associated with this process--recognising the opportunity and the need to include quality of life instruments during the investigation, choosing the most suitable instrument(s) and interpreting the results. To be useful in clinical trials, quality of life measures must be both responsive (able to detect all important differences) and valid. Generic instruments are applicable to a wide variety of populations but may lack responsiveness. Disease-specific instruments are more likely to be responsive and are directly relevant to patients and clinicians. The approach to measurement in a specific clinical trial should be dictated by the goals of the investigators.

Data Interpretation, Statistical↗
PubMed1991

Mechanism of bronchodilator effect in chronic airflow limitation.

OBJECTIVE: To examine the mechanisms through which two bronchodilators (theophylline and salbutamol) influence dyspnea during daily activities. METHODS: Twenty-four patients with chronic airflow limitation participated in a multiple crossover, randomized, placebo-controlled trial. The effect of theophylline and salbutamol, alone or combined, on pulmonary function and dyspnea during daily activities was examined. Correlations of changes in forced expiratory volume in 1 second (FEV1) and maximum expiratory pressures (MIPs) (independent variables) and changes in dyspnea score during daily activities (dependent variable) were also examined. RESULTS: The two drugs proved to be beneficial the effects in general were additive rather than synergistic. The drugs improved the FEV1; theophylline significantly improved the MIPs. The correlation between the changes in FEV1 and those in dyspnea score, after adjustment for the changes in MIPs, was 0.55 (p less than 0.001). The correlation between the changes in MIPs and those in dyspnea score, after adjustment for the changes in FEV1, was 0.39 (p less than 0.001). CONCLUSIONS: Changes in airway calibre and in respiratory muscle strength play an independent and important role in dyspnea during daily activities in patients with chronic airflow limitation. Changes in airway calibre may be of greater importance.

Activities of Daily Living↗
PubMed1991

Interpreting changes in quality-of-life score in N of 1 randomized trials.

To provide additional evidence regarding the plausible range of the differences in health-related quality of life (HRQL) questionnaire scores within which the minimal important difference (MID) falls, we reviewed the results of 32 randomized controlled trials in individual subjects (N of 1 RCTs) with chronic diseases. These trials had been conducted to establish whether a patient was obtaining more good than harm from a medication. Each N of 1 RCT included a series of pairs of treatment periods, one period on active drug, and one on placebo or alternative drug. We examined the relationship between small (MID), medium, and large differences between periods within pairs, as indicated by Global Ratings and differences between these same periods according to HRQL questionnaires. The results showed a mean difference of 0.29 points per question in HRQL questionnaire scores corresponded to the MID. Differences of approximately 0.66 points per question corresponded to a moderate difference as ranked by the Global Rating; difference of about 1.09 points per question represented marked difference.

Drug Therapy↗
PubMed1991

Clinical usefulness of n-of-1 randomized controlled trials in patients with nonreversible chronic airflow limitation.

To determine if n-of-1 randomized controlled trials (n-of-1 RCT) are useful in the care of patients with nonreversible chronic airflow limitation (CAL). Individual trials had a double-blind, randomized, multiple crossover design. Patients with CAL were recruited from several respirology practices. For each individual trial the main outcome measure was a symptom questionnaire; peak flow measurements were used as a secondary measure. Physicians' plans of management (before and after trials) and confidence in the plans were determined. The proportion of trials that provided a definite clinical or statistical answer was established. Patients were followed, and long-term adherence to decisions based on n-of-1 RCT was examined. A total of 26 n-of-1 RCT in patients with CAL were attempted; 18 of these (69%) were completed. After 17 (94%) of the completed trials clinicians expressed a high degree of confidence in their management plans, confidence that was not, in any case, present before the trial. After 8 n-of-1 RCT (44% of all completed, or 31% of all trials) clinicians decided to stop the drug, which would otherwise have been continued indefinitely. In all 17 of the clinically definite n-of-1 RCT, the management decision that followed the trial was still being adhered to 40 months (on average) after completion of the trial. The results support the feasibility and usefulness of n-of-1 RCT in respirology practice.

Double-Blind Method↗
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↗
PubMed1990

The n-of-1 randomized controlled trial: clinical usefulness. Our three-year experience.

OBJECTIVE: To review the feasibility and effectiveness of n-of-1 randomized controlled trials (n-of-1 trials) in clinical practice. DESIGN: Individual trials were double-blind, randomized, multiple crossover trials. The impact of n-of-1 trials was determined by eliciting physicians' plans of management and confidence in those plans before and after each trial. SETTING: Referral service doing n-of-1 trials at the requests of community and academic physicians. OBJECT of ANALYSIS: All trials were planned, started, and completed by the n-of-1 service. MEASURES OF OUTCOME: The proportion of planned n-of-1 trials that were completed and the proportion that provided a definite clinical or statistical answer. A definite clinical answer was achieved if an n-of-1 trial resulted in a high level of physician's confidence in the management plan. Specific criteria were developed for classifying an n-of-1 trial as providing a definite statistical answer. MAIN RESULTS: Seventy-three n-of-1 trials were planned in various clinical situations. Of 70 n-of-1 trials begun, 57 were completed. The reasons for not completing n-of-1 trials were patients' or physicians' noncompliance or patients' concurrent illness. Of 57 n-of-1 trials completed, 50 provided a definite clinical or statistical answer. In 15 trials (39% of trials in which appropriate data were available), the results prompted physicians to change their "prior to the trial" plan of management (in 11 trials, the physicians stopped the drug therapy that they had planned to continue indefinitely). CONCLUSION: We interpret the results as supporting the feasibility and usefulness of n-of-1 trials in clinical practice.

Adult↗
PubMed1990

To what extent do congestive heart failure patients in sinus rhythm benefit from digoxin therapy? A systematic overview and meta-analysis.

PURPOSE: To reappraise the effectiveness of digoxin for the treatment of congestive heart failure (CHF) in patients with sinus rhythm in light of data from recently published randomized controlled trials and to quantitatively assess its usefulness. STUDY IDENTIFICATION: Computerized searches of the MEDLINE database were performed, and the reference list of each retrieved article was reviewed. STUDY SELECTION: Review of more than 360 citations and the reference lists of 19 review articles and 61 potentially relevant articles revealed seven double-blind randomized controlled trials that were included in this overview. DATA EXTRACTION: Study quality was assessed and descriptive information concerning the study populations, the specific interventions, and clinically relevant outcome measurements was extracted. RESULTS OF DATA SYNTHESIS: The common odds ratio for CHF deterioration while receiving digoxin versus placebo was 0.28, with a 95% confidence interval of 0.16 to 0.49. Predictors of digoxin benefit included presence of a third heart sound and the severity and duration of CHF. CONCLUSION: Data from seven trials of high methodologic quality suggest that, on average, one out of nine patients with CHF and sinus rhythm derive a clinically important benefit from digoxin (with a 95% confidence interval of 1/33 to 1/5).

Digoxin↗
PubMed1990

N of 1 randomized trials for investigating new drugs.

Presently, in the process of new drug development, large sample parallel group randomized trials are often begun without the detailed knowledge of optimal dose, most responsive patient group, and optimal outcomes which would be desirable. We propose that randomized trials in individual subjects (N of 1 RCTs) could be used to elucidate these issues at an early stage of drug development. In appropriate conditions N of 1 RCTs can be used to define the rapidity with which a drug begins and ceases its clinical action, the likely range of the optimal drug dose, and the optimal outcomes on which subsequent trials should focus. N of 1 RCTs can also generate initial estimates of the proportion of patients who respond to a new agent and for determining sample size, inclusion criteria, and dosage regimen(s) for subsequent parallel group trials. We provide an example of 14 N of 1 RCTs of amitriptyline in fibrositis that illustrate the ways in which N of 1 RCTs can elucidate these issues. The multiple uses of N of 1 RCTs suggest that the method has immense potential for use in the early phases of drug development programs.

Amitriptyline↗