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Biomedical subjects

R B Haynes

Publications and source records attributed to R B Haynes.

At least 109 records · Page 6Linked to original sources
PubMed1989

Searching MEDLINE for randomized clinical trials involving care of the newborn.

Randomized clinical trials make up only a small fraction of published articles concerning care of the newborn infant and an even smaller fraction of articles about all human subjects. The busy pediatrician who wants to keep abreast of the medical literature requires strategies to detect such relevant studies promptly and reliably. Computer searching of MEDLINE is an attractive, potentially powerful but not sufficiently validated means of achieving this goal. Therefore, the sensitivity, specificity, and positive predictive value of two MEDLINE search strategies designed to detect randomized clinical trials for prevention and treatment of newborn diseases among all original articles about human subjects appearing in ten pediatric and general medical journals during 1985 were determined. The yield of both MEDLINE searches was compared to that of a manual search. Fifty-three randomized clinical trials of newborn care were identified by hand search among 233 articles concerning care of the newborn and 2,988 original articles about human subjects. The sensitivities of the MEDLINE searches were 53% and 34%, respectively, and the positive predictive values were 82% and 69%, respectively. Specificity of both computer searches was virtually 100%. Twenty-one randomized clinical trials were not identified by either MEDLINE search strategy, 17 of them for failure of the indexer to assign any methodologic terms at all or failure to assign sufficiently stringent methodologic terms. Consequently, sensitivities were higher, 77% and 68% respectively, when no methodologic terms were used during repeat searches. However, positive predictive values decreased concomitantly to 20% or less.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical Trials as Topic↗
PubMed1989

Home blood pressure-measuring devices: a comparative study of accuracy.

Self monitoring of blood pressure by hypertensive patients has been shown to be of value and is increasingly popular. However, the accuracy and ease of use of at least some of the equipment for home use is questionable. We tested 23 pairs of home blood pressure devices, using static methods, trained observers with volunteer subjects and hypertensive patients. Eleven (48%) of the 23 pairs of devices tested were found inconsistent with their duplicate and failed the standards for automated devices of the Association for the Advancement of Medical Instrumentation. Several of the devices, all sold for home use by lay people, contained no instructions whatsoever and even patients using those machines with instructions required further training in blood pressure measurement. While home blood pressure monitoring is useful in certain circumstances, care must be taken in the choice of device, and training is required for all devices.

Blood Pressure Determination↗
PubMed1988

Blood pressure profile in two adult male populations.

Causal blood pressure measurements were recorded in two groups of men aged 40 to 64 years; of the 7024 men in metropolitan Saint John, NB, and the 4044 men in seven suburbs of Quebec who were asked, 5840 (83.1%) and 3097 (76.6%) respectively agreed to participate. Of the Saint John group 9.0% were taking antihypertensive drugs, as compared with only 3.3% of the Quebec group (p less than 0.0001). Among the treated subjects 33% in Saint John and 53% in Quebec still had a diastolic pressure greater than 95 mm Hg (p less than 0.01). Among the participants not taking antihypertensive drugs the systolic blood pressure increased with age, but the diastolic blood pressure increased only slightly up to 55 years of age and then decreased. On average the subjects in Saint John who were not being treated had a systolic pressure 6.2 mm Hg lower and a diastolic blood pressure 3.6 mm Hg lower than their Quebec counterparts (p less than 0.0001). This difference was observed in all the age groups and was not the result of the treatment of a greater proportion of the Saint John cohort. Despite the higher blood pressures and the smaller number receiving adequate treatment in the Quebec group, the rate of death due to coronary artery disease was 10% lower than that in the Saint John group. A bias in the data from Quebec may have influenced the magnitude of the differences between the two samples, but if present it should have underestimated the blood pressures in the Quebec group and therefore not have changed the outcome.

Adult↗
PubMed1988

Selected principles of the measurement and setting of priorities of death, disability, and suffering in clinical trials.

Measurements of the cause of death and of disability and suffering caused by nonfatal events add important dimensions to clinical trials even when mortality is the major outcome event. Assessing the cause of death requires special attention to criteria, documentation, and adjudication. Disability is measured through having patients perform objective tasks and functions, such as those related to "daily living," and assesses health from the perspective of the provider. Suffering is measured from the patient's viewpoint by multiple attribute measures and profiles, goal attainment scaling, and utility ratings, in which the patient's preferences for various health states are assessed. Having collected information on death, disability and suffering, the investigator faces decisions concerning setting their priorities when one measure (such as death) precludes the assessment of another or when there are disagreements among the measures.

Activities of Daily Living↗
PubMed1988

Cardiovascular effects of smoking in patients with ischemic heart disease.

The cardiovascular effects of smoking, including the occurrence of ventricular arrhythmias, were examined in 52 patients with ischemic heart disease. The study was a randomized, crossover comparison between smoking six cigarettes and nonsmoking with observer-blinded primary outcome measurements. Continuous Holter ECG recording for four hours showed no significant differences in the proportion of patients experiencing ventricular ectopy or the total number and complexity of ventricular premature beats during smoking vs nonsmoking. Aside from the first cigarette, smoking did not significantly alter blood pressure or heart rate. Mean (+/- SEM) plasma epinephrine (pg/ml) increased (p = 0.02) from baseline (52 +/- 4) to a maximum of 64 +/- 6 at 240 minutes with younger subjects exhibiting a more marked rise (p = 0.02) than subjects over 55 years of age. Plasma norepinephrine was unchanged by smoking. A power calculation confirmed the conclusion that the resumption of smoking after overnight abstention does not acutely increase the occurrence of ventricular ectopic activity in patients with ischemic heart disease.

Adult↗
PubMed1987

Planning for the information age: a survey of microcomputer use in a faculty of health sciences.

Microcomputers can greatly enhance information processing by clinicians and improve the quality of health care. We surveyed 983 full- and part-time faculty members to assess the state of microcomputer use in the Faculty of Health Sciences at McMaster University, Hamilton, Ont. The ratio of faculty members to microcomputers was close to 1; however, 29% of the full-time and 52% of the part-time members who responded indicated that they did not use a computer. Among those who did, the range of applications was generally limited. There was no mention of more advanced uses such as diagnosis, treatment and patient records. Only about 30% of the respondents had taken a computer course, but all indicated a desire to take courses (on average, three of the seven listed in the questionnaire). Our results showed an extensive but unequal distribution of microcomputers and revealed the need for planning and education to put them to optimal use.

Computers↗
PubMed1987

A controlled trial of teaching critical appraisal of the clinical literature to medical students.

We carried out a controlled trial of teaching the critical appraisal of clinical literature among final-year clinical clerks. Tutors at two of four teaching hospitals were offered a short course in the critical appraisal of clinical articles that describe diagnostic tests and treatments and were assisted in identifying and appraising specialty-specific articles that described those diagnostic tests and treatments that clinical clerks were sure to encounter during their clerkship tutorials. Tutors and clerks at the other two hospitals received no special intervention and served as controls. Experimental and control clinical clerks completed pretests and posttests of their ability to take and defend a stand on whether to apply specific diagnostic tests and treatments in specific clinical situations. Experimental clerks demonstrated both statistically and "clinically" significant increases in their critical appraisal skills, improving 37% on the diagnostic test exercise and 8% on the treatment exercise; control students' scores deteriorated for both.

Clinical Clerkship↗
PubMed1987

Functional status changes following medical or surgical treatment for cerebral ischemia. Results of the extracranial-intracranial bypass study.

To determine the value of extracranial-intracranial arterial anastomosis (EC/IC bypass), we randomly allocated 1377 patients with symptomatic atherosclerosis of the internal carotid or middle cerebral arteries to medical care alone or to EC/IC bypass with continuing medical care. As previously reported, surgery did not reduce--or significantly increase--the risk of stroke. Functional status data collected during the trial provide new information. Six weeks following entry, surgical patients showed greater dysfunction in the following activities: fluency of speech, getting in and out of bed, sitting down and standing up, toileting, cutting food and pouring beverages, and dressing and undressing. At 4.5 months, surgical patients still exhibited greater dysfunction in toileting, with nonsignificant trends in several other activities. From six months onward, there were no significant differences between the groups. Thus, EC/IC bypass results in transient worsening of functional status beyond the immediate perioperative period.

Activities of Daily Living↗
PubMed1987

Patient compliance and the conduct and interpretation of therapeutic trials.

Low patient compliance with prescribed treatments is a very common problem in clinical care and can seriously distort the generalizability and validity of controlled clinical trials. Aside from undermining the benefit of any treatment, noncompliance is often, but unpredictably, a marker for adverse patient outcomes independent of any treatment effect. The proper management of compliance in therapeutic trials depends in part on the objectives of the trial. If the purpose of the study is to determine whether a treatment does more good than harm to those who take it ("efficacy"), then noncompliers should be prevented from entering the trial. In a study of "effectiveness" (to determine whether a treatment does more good than harm to those to whom it is offered), quite the opposite approach is required. Regardless of the purpose of the trial, efforts should be made to balance the numbers of low compliers across the treatment groups, compliance should be monitored, and compliance improving strategies should be employed unless the main objective of the trial is to observe natural compliance. In all studies, because of the bias that noncompliance can have on results, the main analysis should include all those entered, whether or not compliant with the treatment regimen.

Clinical Trials as Topic↗
PubMed1987

Computer-aided quality assurance. A critical appraisal.

Computerized information systems hold the promise of overcoming problems in the management of clinical information Many of the claims of the creators and promoters of these systems, however, are not based on sound clinical studies. To determine the ability of computer information systems to improve the quality of medical care, we applied methodologic criteria to published articles in the field. Only 30 (22%) of 135 articles reported preplanned investigations, and only half of these met minimal criteria for scientific investigations. Fourteen studies were well designed and executed. All studies reported improvements in the process of care. However, patient outcomes were not measured, not affected, or only minimally influenced. While computer information systems show increasing potential, more work is required to enhance their effect on the quality of care and thus on patient outcomes.

Evaluation Studies as Topic↗
PubMed1986

A framework for clinical evaluation of diagnostic technologies.

Most new diagnostic technologies have not been adequately assessed to determine whether their application improves health. Comprehensive evaluation of diagnostic technologies includes establishing technologic capability and determining the range of possible uses, diagnostic accuracy, impact on the health care provider, therapeutic impact and impact on patient outcome. Guidelines to determine whether each of these criteria have been met adequately are presented. Diagnostic technologies should be disseminated only if they are less expensive, produce fewer untoward effects and are at least as accurate as existing methods, if they eliminate the need for other investigations without loss of accuracy, or if they lead to institution of effective therapy. Establishing patient benefit often requires a randomized controlled trial in which patients receive the new test or an alternative diagnostic strategy. Other study designs are logistically less difficult but may not provide accurate assessment of benefit. Rigorous assessment of diagnostic technologies is needed for efficient use of health care resources.

Clinical Trials as Topic↗
PubMed1986

The role of before-after studies of therapeutic impact in the evaluation of diagnostic technologies.

Studies in which clinicians' therapeutic plans are determined before and after application of a new test offer an attractive alternative to randomized trials as a strategy for establishing the usefulness of diagnostic technologies. To maximize scientific credibility such studies should include a number of design features: specific clinical questions should be addressed; consecutive patients presenting with a clinical problem should be entered; the test's accuracy should be assessed; and changes in therapy should be described in sufficient detail to allow an estimate of the impact on patient outcome. Even with attention to these issues, the validity of before-after studies of therapeutic impact is limited by possible discrepancies between clinicians' stated plans and actual behavior, and by the often tenuous link between change in therapy and patient benefit. Before-after designs will be most useful in primary investigations which, if positive, should be followed by more rigorous studies to establish patient benefit.

Diagnosis↗
PubMed1986

Guidelines for the clinical and economic evaluation of health care technologies.

The health care system is routinely confronted with promising new technologies. In the past, most new technologies have been integrated into clinical practice without a rigorous demonstration of their effectiveness or efficiency. In order to provide a more rational approach to the adoption and utilization of health technology a comprehensive set of guidelines for both clinical and economic evaluation is proposed. While conceived of as an ideal that is unlikely to be universally met in practice, it is argued that decision making can be improved by striving towards this goal. The clinical guidelines stress the advantages of subjecting major new technologies to randomized controlled trials and insisting upon a demonstration of patient benefit in the application of diagnostic technologies. The economic guidelines stress comparisons with relevant alternative uses of the resources and the assessment of the impact on the quality of life. While application of the guidelines will produce rigorous and useful evidence, the final decisions concerning the allocation of health care resources must rest fundamentally on social value judgements and not solely, or even primarily, on informed expert opinion.

Clinical Trials as Topic↗
PubMed1986

Hypertension control in two Canadian communities: evidence for better treatment and overlabelling.

We evaluated the prevalence and control of hypertension in two Canadian cities without university medical centre facilities. A stratified multistage probability sample was selected, and we interviewed 6258 adults between the ages of 30 and 69 inclusive. Blood pressure measurements were obtained during home interviews. Up to two further visits were made to people with untreated blood pressure elevation. By a diagnostic criterion of 90 mmHg, the hypertension prevalence was 114/1000. Six per cent of the hypertensives were undetected, 6% detected but untreated, 17% treated but uncontrolled and 70% were being treated and controlled. Control was better in females and older subjects. These findings show no disadvantages to hypertensives living away from university medical centres. We found a hypertension prevalence of 143/1000 among people who reported being diagnosed as hypertensive but who had normal blood pressure while not on medication. These results suggest a problem with over-labelling of hypertensives.

Adult↗
PubMed1986

Is weight loss an effective treatment for hypertension? The evidence against.

Although there are many studies reporting correlations between relative body weight and blood pressure, the correlations are generally of low order. Furthermore, these observational studies provide, at best, circumstantial evidence concerning the effect of weight reduction on elevated blood pressure. After outlining key methodologic criteria for testing the hypothesis that weight loss lowers blood pressure among hypertensive obese subjects, this article reviews the best intervention studies that are available. Despite the demonstration in these randomized trials that weight reduction programs can lower weight successfully, the results for blood pressure lowering are in considerable disagreement. Two studies reported significant lowering of both systolic and diastolic blood pressure, one found significant lowering of systolic pressure only, and two failed to find significant differences in either. The definitive study of substantial weight loss among patients receiving no other antihypertensive treatment or standardized medical treatment with long-term follow-up has yet to be done. At best, weight loss offers very limited benefit for overweight hypertensives. At worst, weight loss programs are expensive to run, cause considerable patient discomfort and may delay the implementation of more effective therapy.

Blood Pressure↗
PubMed1986

How to keep up with the medical literature: I. Why try to keep up and how to get started.

Patient care is often outmoded because physicians lack awareness about important advances in medical knowledge. According to physicians, reading journals is the most popular method for staying informed, but the great volume of journal literature precludes clinicians' from reading all of it. In this first of six articles on keeping up with the medical literature, we describe three strategies to enhance the efficiency and effectiveness of journal reading. First, priority should be given to reading original articles concerning reports of planned investigations because only these articles provide sufficient details to assess the relevance, validity, and clinical application of new knowledge. Second, reading should be restricted to articles of direct pertinence to one's clinical practice. Third, the methods section of articles should be quickly screened first to select studies that have used sufficiently high standards to warrant clinical action based on study results.

Education, Medical, Continuing↗