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Biomedical subjects

A Willan

Publications and source records attributed to A Willan.

At least 37 records · Page 2Linked to original sources
PubMed1996

Ardeparin (low-molecular-weight heparin) vs graduated compression stockings for the prevention of venous thromboembolism. A randomized trial in patients undergoing knee surgery.

BACKGROUND: Deep vein thrombosis is common in patients undergoing major knee surgery. Static graduated compression stockings effectively prevent venous thrombosis in general surgery. Because of the demonstrated prophylactic efficacy of pneumatic compression in knee surgery, the similar efficacy of static graduated compression and pneumatic compression in neurosurgery, and the easier use of static graduated compression in knee surgery, graduated static compression stockings were used as the control arm in our clinical trial. Although low-molecular-weight heparin had been shown to be effective in general surgery and hip replacement, its efficacy was unproved in knee surgery. METHODS: A double-blind, randomized trial compared the combination of low-molecular-weight heparin and graduated compression stockings with graduated compression stockings alone in patients undergoing major knee surgery. Patients received either ardeparin (Normiflo) (low-molecular-weight heparin), 0.005 mL/kg (50 anti-Xa U/Kg), or placebo. Both were administered subcutaneously twice daily commencing 12 to 24 hours after surgery and continued for 14 days or until discharge, if sooner. Both study groups wore graduated compression stockings. Bilateral venography was performed on day 14, or sooner if the patient was ready for discharge. RESULTS: One hundred twenty-two patients were allocated to receive ardeparin and 124 received placebo. Ninety-six patients in the ardeparin group and 103 in the placebo group had evaluable venograms. Deep vein thrombosis was detected in 28 patients in the ardeparin group and in 60 in the placebo group. Proximal deep vein thrombosis was detected in two patients who received ardeparin and 16 who received placebo. One patient in each group, both of whom did not have venography, experienced pulmonary embolism. Thus, deep vein thrombosis or pulmonary embolism was detected in 29 (29.9%) of the 97 patients in the ardeparin group and in 61 (58.7%) of the 104 patients in the placebo group, a relative risk reduction of 49% (P < 00.1). The rate of major bleeding in the ardeparin group was 2.5%, compared with 2.4% in the placebo group. CONCLUSION: Ardeparin administered postoperatively twice daily is effective and safe for the prevention of venous thrombosis in patients undergoing major knee surgery. Whereas graduated compression stockings have been shown to be effective prophylactic agents in general surgery and neurosurgery, they have little effect in knee surgery.

Aged↗
PubMed1996

Reliability of the international normalized ratio for monitoring the induction phase of warfarin: comparison with the prothrombin time ratio.

The International Normalized Ratio (INR) was introduced to reduce the variability of prothrombin time (PT) reporting. One potential problem with the use of the INR is the assumption that its reliability is reduced when it is used to monitor patients during the induction phase of treatment. This shortcoming arises because the model used to establish the INR system is based on the use of pooled plasma from patients stabilized on warfarin for at least 6 weeks. Because the prolongation of the PT by warfarin during the induction phase mainly reflects reduction in factor VII levels (whereas the prolongation of the PT after 6 weeks of stabilization reflects reductions in factors X, II, and VII), there exists a potential for loss of accuracy of the INR during warfarin induction. To overcome this potential problem, it has been suggested that the PT ratio should be used to report results during the induction phase of treatment and that the INR system should be reserved for reporting results after the patient has been stabilized. This approach is confusing to the clinician. In addition, the validity of this approach has never been demonstrated in a clinical study. To address this issue, we studied 43 patients for the first 5 days after they started warfarin therapy. We measured the PT in the same plasma samples from each patient with five different commercial thromboplastins. The variance in the PT ratios among the five thromboplastins was compared with the variance obtained with the INR values derived from the PT ratios when using the international sensitivity indexes provided by the manufacturer. Our results indicate that, even during the induction phase, there is less variance with the INR system than with the PT ratio system.

Anticoagulants↗
PubMed1996

A controlled trial of nurse practitioners in neonatal intensive care.

OBJECTIVE: To compare a clinical nurse specialist/neonatal practitioner (CNS/NP) team with a pediatric resident team in the delivery of neonatal intensive care. DESIGN: Randomized, controlled trial. SETTING: A 33-bed tertiary-level neonatal intensive care unit. PATIENTS: Of 821 infants admitted to the neonatal intensive care unit between September 1991 and September 1992, 414 were randomized to care by the CNS/NP team, and 407 were randomized to care by the pediatric resident team. INTERVENTION: Infants assigned to the CNS/NPs team were cared for by CNS/NPs during the day and by pediatric residents during the night. Infants assigned to the pediatric resident team were cared for by pediatric residents around the clock. Neonatologists supervised both teams. MEASURES: Outcome measures included mortality; number of neonatal complications; length of stay; quality of care, as assessed by a quantitative indicator condition approach; parent satisfaction with care, measured using the Neonatal Index of Parent Satisfaction; long-term outcomes, measured using the Minnesota Infant Development Inventory; and costs. RESULTS: There were 19 (4.6%) deaths in the CNS/NP group and 24 (5.9%) in the resident group (relative risk [RR], 0.78; confidence interval [CI], 0.43 to 1.40). In the CNS/NP group, 230 (55.6%) neonates had complications, in comparison with 220 (54.1%) in the resident group (RR, 1.03; CI 0.91 to 1.16). Mean lengths of stay were 12.5 days in the CNS/NP group and 11.7 days in the resident group (difference in means, 0.8 days; CI, -1.1 to 2.7). The performance on the indicator conditions was comparable in the two groups except for two instances, jaundice and charting, both of which favored the CNS/NP group. Mean scores on the Neonatal Index of Parent Satisfaction were 140 in the CNS/NP group and 139 in the resident group (difference in means, 1.0; CI, -3.6 to 5.6). In the CNS/NP group, 6 (2.6%) infants performed 30% or more below their age level in the Minnesota Infant Development Inventory, in comparison with 2 (0.9%) in the resident group (RR, 2.87; CI, 0.59 to 14.06) The cost per infant in the CNS/NP group was $14,245 and in the resident group $13,267 (difference in means, $978; CI, -1303.18 to 3259.05). CONCLUSIONS: CNS/NP and resident teams are similar with respect to all tested measures of performance. These results support the use of CNS/NPs as an alternative to pediatric residents in delivering care to critically ill neonates.

Female↗
PubMed1995

Determinants in Canadian health care workers of the decision to withdraw life support from the critically ill. Canadian Critical Care Trials Group.

OBJECTIVE: To examine the attitudes of health care workers regarding the withdrawal of life support. DESIGN: Cross-sectional survey. PARTICIPANTS: Attending staff, house staff, and intensive care unit (ICU) nurses in 37 Canadian university-affiliated hospitals. MAIN OUTCOME MEASURES: Health care workers' ratings of the importance of 17 factors considered in the decision to withdraw life support, and their ratings of five levels of care ranging from comfort measures to intensive care in two of 12 different clinical scenarios. RESULTS: We surveyed 1361 respondents (149 of 167 potentially eligible ICU attending staff, 142 of 173 ICU house staff, and 1070 of 1455 ICU nurses, with response rates of 89%, 82% and 74%, respectively). The most important factors were likelihood of surviving the current episode, likelihood of long-term survival, premorbid cognitive function, and age of the patient. In choosing the level of care for the patient scenarios, the same option was chosen by more than 50% of respondents in only one of 12 scenarios; opposite extremes of care were chosen by more than 10% of the respondents in eight of 12 scenarios. Respondent characteristics affecting choices included the number of years since graduation, the city and province in which they worked, the number of beds in their ICU, and their assessment of the likelihood that they would withdraw life support in comparison with their colleagues (P < .001 for all comparisons). CONCLUSIONS: While ICU health care workers consistently identify a number of patient factors as important in decisions to withdraw care, there is extreme variability, which may be explained in part by the values of individual health care providers.

Adult↗
PubMed1994

Determining a minimal important change in a disease-specific Quality of Life Questionnaire.

This study was carried out to determine whether the minimal important difference, in evaluative quality of life instruments which use a 7-point scale, is similar across individual domains and for both improvement and deterioration. Thirty nine adults with asthma were studied, using an 8 week cohort with assessments at 0, 4 and 8 weeks. The outcomes were the Asthma Quality of Life Questionnaire and global rating of change. For overall asthma-specific quality of life and for all individual domains (activities, emotions, symptoms), the minimal important difference of quality of life score per item was very close to 0.5 (range: 0.42-0.58); differences of approximately 1.0 represented a moderate change (range: 0.77-1.51); differences greater than 1.5 represented large changes. Changes for improvement and deterioration were very similar. The changes in quality of life score that represent a minimal important difference are very similar to those observed for other evaluative instruments. The observation that the minimal important difference is consistent across domains and for both improvement and deterioration will facilitate interpretation of results of studies examining quality of life.

Adult↗
PubMed1994

Quality of life after myocardial infarction.

The objective of this work was to develop and test a questionnaire to measure health-related quality of life for patients after myocardial infarction (MI). In a cross-sectional survey, 63 patients identified the most frequent and important problems following acute myocardial infarction. The Quality of Life after Myocardial Infarction (QLMI) instrument was developed on the basis of these most frequent and important problems. The QLMI was administered, along with instruments measuring health utilities, social function, and emotional function, in a randomized trial of rehabilitation versus conventional care. The most frequent and important problems fell into areas of symptoms, restriction, confidence, self-esteem, and emotions, each of which is represented in the 26-item QLMI. Effect sizes of the overall QLMI in differentiating between rehabilitation and control groups (0.35), and in detecting improvement over 12 months (1.22) were comparable or larger than any other instrument. The Pearson's correlation coefficient between QLMI administered at 8 and 12 months following AMI varied between 0.75 and 0.87 for the five domains and the overall score. We found substantial correlations of the QLMI with other measures with moderate concordance with predictions about how the instrument should behave if it is a valid measure of health-related quality of life. The QLMI demonstrates a high degree of reliability, and is more responsive than other questionnaires. Relations between the QLMI and other measures provide moderate to strong evidence of its validity in discriminating between patients following AMI according to their health-related quality of life, and in measuring changes in health-related quality of life over time.

Female↗
PubMed1994

In search of power and significance: issues in the design and analysis of stochastic cost-effectiveness studies in health care.

Application of techniques such as cost-effectiveness analysis (CEA) is growing rapidly in health care. There are two general approaches to analysis: deterministic models based upon assumptions and secondary analysis of retrospective data, and prospective stochastic analyses in which the design of a clinical experiment such as randomised controlled trial is adapted to collect patient-specific data on costs and effects. An important methodological difference between these two approaches is in the quantification and analysis of uncertainty. Whereas the traditional CEA model utilizes sensitivity analysis, the mean-variance data on costs and effects from a prospective trial presents the opportunity to analyze cost-effectiveness using conventional inferential statistical methods. In this study we explored some of the implications of moving economic appraisal away from deterministic models and toward the experimental paradigm. Our specific focus was on the feasibility and desirability of constructing statistical tests of economic hypotheses and estimation of cost-effectiveness ratios with associated 95% confidence intervals. We show how relevant variances can be estimated for this task and discuss the implications for the design and analysis of prospective economic studies.

Confidence Intervals↗
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

A measurement process for evaluating clinical teachers in internal medicine.

With input from faculty members and residents in the internal medicine residency training program at McMaster University, Hamilton, Ont., the authors developed a form to evaluate attending physicians in clinical teaching units according to 14 domains of performance. Although brief, the form included all main areas of teacher performance, allowed specification of attending physician behaviour and differentiated areas of strengths and weaknesses between and within attending physicians. The authors describe the new evaluation process and the results for 41 attending physicians.

Canada↗
PubMed1993

Should unpublished data be included in meta-analyses? Current convictions and controversies.

OBJECTIVE: To identify the extent to which meta-analyses currently include unpublished data and whether editors, meta-analysts, and methodologists believe unpublished material should be included. DESIGN: This article describes two related studies: a literature review and a cross-sectional survey. SAMPLE SELECTION: For the literature review, we identified all articles indexed by the key word meta-analysis from January 1989 to February 1991 and determined whether unpublished material had been searched for, obtained, and included in the meta-analyses. For the cross-sectional survey, we surveyed authors of these meta-analyses, authors of articles addressing methodological issues in meta-analysis published during the same period, and editors of journals in which both types of articles were published. INTERVENTION: We asked the respondents about their attitudes concerning inclusion of unpublished data and publication of articles from which data had previously been included in a scientific overview. MAIN OUTCOME MEASURES: Inclusion of unpublished data and opinions about whether unpublished material should be included in overviews and whether prior inclusion of data in an overview should bear on publication. RESULTS: Of 150 meta-analyses, 46 (30.7%) included unpublished data in their primary analysis. Of authors surveyed, 85% responded. Of the meta-analysts and methodologists, 77.7% felt that unpublished material should definitely or probably be included in scientific overviews; this was true of 46.9% of the editors. A total of 86.4% of the meta-analysts and methodologists and 53.2% of the editors felt that inclusion of data in a prior overview should have no bearing on full publication of original research. CONCLUSION: While inclusion of unpublished data in scientific overviews remains controversial, most investigators directly involved in meta-analysis believe that unpublished data should not be systematically excluded. The most valid synthesis of available information will result when meta-analysts subject published and unpublished material to the same rigorous methodological evaluation and present results with and without unpublished sources of data.

Data Collection↗
PubMed1993

Effect of a new nootropic agent, CGS 5649B, on cognition, function, and behavior in dementia.

To determine the efficacy of CGS 5649B, the authors conducted a series of randomized, double-masked, single-subject studies using pairs of treatment periods, each pair including four weeks of active drug administration and four weeks of placebo administration. Thirty-two moderately demented patients completed three treatment pairs, receiving doses of 90, 200, or 600 mg of CGS 5649B during the active periods. Two patients met criteria for individual response in the behavioral measures. In the group analysis none of the differences achieved statistical significance. The authors conclude that CGS 5649B had a favorable impact on behavior for two of 32 patients.

Adult↗
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

Measuring quality of life in the frail elderly.

This study was carried out to develop and test the Geriatric Quality of Life Questionnaire (GQLQ), a health-related qualify of life (HRQL) questionnaire designed for the frail elderly. One hundred patients were asked to identify areas of their daily lives affected by their health. The GQLQ, developed on the basis of the results, the Rand Physical and Emotional Function Questionnaires, and the Barthel Index, were administered serially to a group of 76 patients participating in a randomized trial of a Geriatric Day Hospital. Participants in all phases of the study were over 65 years of age, living in their own home but with sufficient functional status impairment to compromise their ability to live independently. The GQLQ includes 25 questions focusing on activities of daily living (ADL), symptoms, and emotional function. In the ADL and Symptom domains respondents define personal problem areas. The responsiveness coefficients of the GQLQ ADL and Symptom domains (0.26 and 0.30 respectively) were similar to those of the Rand Physical Function instrument and the Barthel Index (0.29 and 0.20). The responsiveness coefficient of the GQLQ Emotional Function domain (0.50) was similar to that of the Rand Emotional Function instrument (0.63). Correlations between the GQLQ ADL domain and the Barthel Index (0.41), and between GQLQ and the Rand Physical Function instrument (0.30), were similar to the correlation between the Barthel Index and Rand Physical Function (0.40). While the GQLQ captures important areas of health-related quality of life impairment for the frail elderly, we failed to show any advantages in either responsiveness or validity to existing, simpler measures. New, specific instruments should be tested in head-to-head comparisons with existing measures, particularly generic instruments, before dissemination.

Activities of Daily Living↗
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

A diagnostic and therapeutic N-of-1 randomized trial.

The objective of this paper is to study the effect of amitriptyline on a young woman with symptoms of lightheadedness, palpitations, somnolence and fatigue. We conducted a single case (N-of-1) randomized trial including three pairs of treatment periods. Each pair included one four-week period when the patient was receiving amitriptyline and one four-week period when the patient was receiving placebo. The clinical setting was a secondary care internal medicine practice. During active treatment periods, amitriptyline was given in a dose of 100 mg each evening. Efficacy symptoms included lightheadedness, headaches and somnolence/fatigue. Side-effects of dry mouth and constipation were also monitored. Each symptom was rated on a seven point scale in which higher numbers denoted fewer symptoms. For the combined efficacy score, the mean difference in scores and the associated standard error was in favour of amitriptyline. The most profound effect was on sleepiness. These differences represent clinically important treatment effects. Dry mouth and constipation were worse on the active drug, but differences did not reach statistical significance. Our experience suggests the usefulness of N-of-1 randomized trials in outpatient medical practice, including psychiatric practice.

Adult↗