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Biomedical subjects

M McGregor

Publications and source records attributed to M McGregor.

At least 37 records · Page 2Linked to original sources
PubMed1997

Assessing the impact of health technology assessment.

Methodology for evaluation of impact of health technology assessments (HTAs) is outlined and its use illustrated by applying it to 21 HTAs produced by CETS. Impact on policies and technology diffusion was identified in documents, through interviews, questionnaires, and use of data banks. There was evidence that all but three reports influenced policy and that cost-minimization studies caused savings of between $16 million and $27 million annually. Precise estimates of impact will seldom be possible, but systematic documentation of effects is feasible.

Canada↗
PubMed1997

Use of chiropractic manipulation in lumbar rehabilitation.

The beneficial effects of manipulation in relieving symptoms and enhancing spinal flexibility can be a valuable tool in the transition of persons with low back pain into lumbar rehabilitation programs. Manipulation may hasten their entry into active care, or permit them to complete programs that might otherwise be interrupted by symptomatic recurrence. Manipulation science and technical procedures are reviewed as a basis to help understand the utility of properly integrated chiropractic manipulation strategies.

Biomechanical Phenomena↗
PubMed1997

Manipulation of immune responses via particle-mediated polynucleotide vaccines.

Polynucleotide vaccines are a new approach to immunization that promises qualitative advances in vaccine technology. These vaccines mimic infection in that they result in expression of pathogen gene products in situ, which can elicit both cell-mediated immune responses and humoral responses. This approach has been applied primarily to vaccines against viral diseases, but may be significant for vaccines directed toward bacterial pathogens. Auragen has developed a generally applicable gene transfer technology and, for vaccine applications, has focused on particle-mediated gene transfer to epidermis. Results demonstrate that Accell polynucleotide vaccines induce immune responses toward human immunodefficiency virus (HIV) antigens, influenza A virus antigens, and hepatitis B virus (HBV) antigens in rodent,s swine and primates. Cellular immune responses toward these antigens have been demonstrated in rodents. In a swine influenza a challenge model Accell vaccination provides protection equivalent to that of a commercial killed-whole-virus vaccine. Vaccination of mice by this method toward a Chlamydia pneumoniae major outer-membrane protein elicits a species-specific antibody response.

AIDS Vaccines↗
PubMed1996

Cost effectiveness of screening for primary open angle glaucoma.

OBJECTIVES AND SETTING: To determine the cost effectiveness of screening for glaucoma. METHODS: Information on treatment efficacy, diagnostic methods, epidemiological characteristics of glaucoma, and costs were determined from the literature, from administrative databases, and from experts. Scenarios with different screening frequency, age, participation in screening, compliance with treatment, treatment efficacy, and diagnostic tests were examined. RESULTS: The initial scenario comprised three-yearly screening of subjects aged 40-79 by funduscopy and tonometry, followed by perimetry when abnormalities were discovered. The assumption of levels of participation in screening and of compliance with treatment of 75%, and treatment efficacy of 50% resulted in a cost of $C100,000 per year of blindness prevented. A scenario in which screening was restricted to subjects aged 65-79, with the same input variables, would prevent 81% of the cases of blindness prevented with scenario 1, at a cost of $C42,000 per year of blindness prevented. Screening with tonometry only as the initial diagnostic test in subjects aged 65-79 would result in a cost of $C36,000 per year of blindness prevented, but would only prevent 59% of the cases prevented with scenario 1. CONCLUSIONS: There is as yet no proof that treatment of glaucoma or of high intraocular pressure will arrest the progression of glaucoma to blindness. Even when treatment efficacy is assumed to be as high as 50%, however, the cost effectiveness of most glaucoma screening programmes considered would not be competitive.

Adult↗
PubMed1995

How has extracorporeal shock-wave lithotripsy changed the treatment of urinary stones in Quebec?

OBJECTIVES: To determine the number of people who underwent treatment of urinary stones in Quebec before and after the introduction of extracorporeal shock-wave lithotripsy (ESWL) and to determine how the introduction of ESWL influenced resource utilization. DESIGN: Before-after study; data were obtained from administrative databases and hospital-based cost estimates. SETTING: The 68 acute care hospitals in Quebec in which treatment of urinary stones is undertaken. PATIENTS: Quebec residents admitted to hospital for treatment of urinary stones between the fiscal years 1984 and 1992. OUTCOME MEASURES: Number of people treated for urinary stones per year, total number of procedures per year (including open surgery, percutaneous procedures, retrograde procedures and ESWL), and annual resources (including number of hospital bed-days and direct costs) for treatment of urinary stones used overall and in hospitals with and without ESWL services. RESULTS: Over the study period the number of people treated for urinary stones increased by 59%. As well, the combined frequency of ESWL and surgery (the two main treatment methods) increased by 107%. These increases were largely due to rates of treatment that grew by 52% among women and by 34% among men. The total number of hospital bed-days decreased by 28%, which reflected shorter hospital stays for ESWL. However, despite this decrease, the total direct annual costs were 7% higher in 1992 than in 1984 because of the increased numbers of people treated and procedures performed. In the three hospitals that offered ESWL the number of hospital bed-days and the direct costs of treating urinary stones increased by 49% and $2.5 million respectively. In the 65 other hospitals these figures decreased by 41% and about $2.9 million respectively. CONCLUSIONS: Because of increased intervention rates the total cost of treating urinary stones has risen since the introduction of ESWL. The introduction of ESWL has also been associated with a shift in the use of resources for treating urinary stones to hospitals with a lithotriptor. The reasons for the increased intervention rates are unknown. However, given the possibility of negative health effects and the increased costs, studies to determine whether the increased rates improve health outcomes are warranted.

Adult↗
PubMed1995

Manipulative therapy versus education programs in chronic low back pain.

STUDY DESIGN: A randomized trial was conducted on a representative sample of patients with untreated low back pain lasting 7 weeks or longer, or having more than 6 episodes in 12 months. OBJECTIVES: To contrast the effectiveness of manipulation, a manipulation mimic, and a back education program. Methodologic criticisms of earlier studies were addressed. SUMMARY OF BACKGROUND DATA: Published meta-analyses suggest clinical benefit from manipulation for acute patients. Data are inconclusive for patients having symptoms for longer than 1 month. METHODS: A total of 1267 consecutive patients were screened. Block randomization was used to assign 209 qualifying patients to treatment groups. Self-reported pain and activity tolerance served as primary outcome measures. Patients were assessed at enrollment, after 2 weeks of treatment, and again after 2 weeks without treatment. Multiple teams conducted recruitment, randomization, assessment, treatment, and data analysis independently without sharing information. Treatments were carefully described, monitored, and balanced for physician attention and physical contact effects. RESULTS: A total of 81.3% of subjects completed the study. Confounding factors and missing data were identified in approximately 20% of those completing the final follow-up. Analysis of the remaining data was carried out. A strong time effect under treatment was observed. Greater improvement was noted in pain and activity tolerance in the manipulation group. Immediate benefit from pain relief continued to accrue after manipulation, even for the last encounter at the end of the 2-week treatment interval. CONCLUSION: Time is a strong ally of the low back pain patient. In human terms, however, there appears to be clinical value to treatment according to a defined plan using manipulation even in low back pain exceeding 7 weeks' duration.

Adult↗
PubMed1995

Comparison of 1.5 Tesla and 0.35 Tesla field strength magnetic resonance imaging scans in the morphometric evaluation of the lumbar intervertebral foramina.

OBJECTIVE: To compare magnetic resonance imaging (MRI) scans obtained from 1.5 Tesla (T) MRI units with scans obtained from 0.35T MRI units in the morphometric evaluation of the lumbar intervertebral foramina (IVF). DESIGN: Three dimensions of lumbar IVFs were measured on a cadaveric lumbar spine by using Vernier calipers. The spine was embedded in gelatin to simulate soft tissue and scanned twice in a 1.5T MRI unit (3-mm and 5-mm slice thicknesses) and once in a 0.35T MRI unit (5-mm slice thickness). Measurements from the scans were made independently by three observers. The results obtained from the two units were compared to the actual IVF size (as measured by calipers) and to one another. RESULTS: The greatest superior-to-inferior distance had the strongest statistically significant correlation to the actual cadaver measurements for both the 0.35T and 1.5T imaging units [r = 0.986 (0.35T); r = 0.985 (1.5T at 3 mm) and r = 0.981 (1.5T at 5 mm); p < .0001 in all cases]. Mean differences and standard errors were minimal between measurements made from MRI scans of both 1.5T and 0.35T units and measurements made directly from the cadaveric spine. CONCLUSION: Both imaging units produced images that accurately depicted the actual size of the IVF. The MRI units of 0.35T field strength produced images of high morphometric accuracy. In addition, the potential for side effects and the operating costs are less with 0.35T units. Therefore, 0.35T MRI units may be a prudent choice as a clinical and research imaging tool in the evaluation of the lumbar IVF.

Humans↗
PubMed1994

Can our health services be saved by technology evaluation? The Quebec experience.

The finances to support our health services at their present level are lacking, and much of the shortage is due to new health technologies. Through the utilisation of technology assessment (TA), it is hoped that we may be able to eliminate useless technologies and that the money so saved will allow us to maintain our health care services intact. Such hopes are exaggerated. The uses and limitations of TA are reviewed in the light of recent experience gained with the Conseil d'évaluation des technologies du Québec. Technology assessment has only limited value in exposing ineffective technologies. More often, it can illuminate inappropriate use of technologies. However, its real value lies elsewhere, namely in making difficult choices between different technologies. An example is the choice between expensive, low osmolar contrast media in radiology and the cheaper, high osmolar material which causes more frequent reactions. Credible estimates of how much benefit will result from the commitment of how many extra dollars can facilitate such decisions. However, the user must clearly understand the limitations of cost-effectiveness estimates, which should never be used for policy purposes without full knowledge of all the qualifiers on which the estimates depend.

Canada↗
PubMed1993

Clinical methodologies and incidence of appropriate statistical testing in orthopaedic spine literature. Are statistics misleading?

An analysis of 300 randomly drawn orthopaedic spine articles, published between 1970 and 1990, was performed to assess the quality of biostatistical testing and research design reported in the literature. Of the 300 articles, 269 dealt with topics of an experimental nature, while 31 documented descriptive studies. Statistical deficiencies were identified in 54.0% of the total articles. Conclusions drawn as the result of misleading significance values occurred in 124 experimental studies (46%) while 96 failed to document the form of analysis chosen (35.7%). Statistical testing was not documented in 34 studies (12.6%), while 20 (7.4%) employed analyses considered inappropriate for the specific design structure.

Evaluation Studies as Topic↗
PubMed1993

The reuse of hemodialyzers: an assessment of safety and potential savings.

OBJECTIVE: To evaluate the safety and potential cost savings of hemodialyzer reuse. DATA SOURCES: All English and French articles published from 1960 to 1991 related to hemodialyzer reuse (retrieved through an Index Medicus and MEDLINE search [corrected]), the indexes of eight North American journals from 1960 onward, conference proceedings, association guidelines, and US and Canadian laws and regulations. RESULTS: For health care personnel the reuse of hemodialyzers did not entail any increased risk of infection or exposure to toxic substances if proper control measures were taken. For patients there was no evidence to suggest any excess risk of complications or death as long as precise and appropriate procedures are observed. The "first-use syndrome" can be prevented and should no longer be considered as a reason to favour reuse. A cost-minimization analysis indicated that five uses might save up to $3629 per patient yearly. Thus, the adoption of a policy of reuse in Canada for all eligible patients undergoing long-term hemodialysis could result in direct savings of about $5.8 to $8.9 million per year. CONCLUSION: The health risks associated with hemodialyzer reuse can be reduced to acceptable levels through the rigorous observance of proper quality-assurance and quality-control measures and the use of automated reconditioning equipment. Such a policy could achieve modest savings for the health care system. A decision to reuse should be formally adopted by the institution and accompanied by a precise definition of the standards of quality assurance and control.

Costs and Cost Analysis↗
PubMed1993

Value of routine preoperative chest x-rays: a meta-analysis.

The purpose of this study was to estimate the frequency with which routine postoperative chest x-rays lead to clinically relevant new information. All articles in English, French and Spanish relating to routine chest radiography in North American or European populations were reviewed, using the Medline database and references listed in reviews and periodicals published from 1966 to 1992, inclusive. Twenty-one reports which supplied sufficient information were included for meta-analysis. On average, abnormalities were found in 10% of routine preoperative chest films. In only 1.3% of films were the abnormalities unexpected, i.e., were not already known or would not otherwise have been detected (95% CI: 0 to 2.8%). These findings were of sufficient importance to cause modification of management in only 0.1% (95% CI: 0 to 0.6%). The frequency with which the new information influenced health could not be estimated. Assuming only the direct cost to the health care system of each radiograph ($23), each finding which influenced management in any way would cost $23,000. It is concluded that in North American or European populations when a reliable history and a clinical examination are carried out, the cost of this test is so high relation to the clinical information provided that it is no longer justifiable.

Age Factors↗
PubMed1993

The effect of coffee consumption on serum cholesterol levels.

OBJECTIVE: Studies investigating the association of coffee consumption and serum cholesterol levels report conflicting results. In an attempt to resolve this controversy, we reviewed the literature to answer the question: Is there a true positive association between coffee consumption and serum cholesterol levels? DATA SOURCES: A Medline database search dating back to 1965 was utilized. Key words used in the search were coffee, caffeine and cholesterol. Cholesterol was expanded to include lipoproteins and LDL-, HDL- and VLDL-cholesterol. All articles that presented cholesterol data in association with coffee consumption were examined for references missed by Medline. Recently published articles were located by a hand search through Current Contents and the latest monthly editions of Index Medicus. STUDY SELECTION: Three reviewers made the decision to include all publications that met the following criteria: a) reported original experimental results; b) reported total serum cholesterol levels; and c) were published in peer-reviewed journals. DATA EXTRACTION: Two to four articles were read and analyzed each week in chronological order. Independent data extraction was performed by three reviewers, who then met as a group once a week to cross-check the analyses. DATA SYNTHESIS: A trend, representing the association between coffee consumption and serum cholesterol, was calculated for each study. The trend was based on the percent difference in cholesterol values between subjects drinking four or more cups of coffee per day in comparison to those drinking zero or less than one cup of coffee each day. In order to compare studies that reported different cup sizes and different levels of intake, weighted mean cholesterol levels were calculated. In studies discussing the data in terms of correlations, trends were established according to the r values provided by the authors. CONCLUSIONS: The majority of studies demonstrated a positive trend in at least one subpopulation of their subjects, indicating that serum cholesterol levels increase with increasing coffee consumption. Stronger trends were seen among subjects drinking boiled coffee than in those drinking filtered, decaffeinated or instant coffee. However, most studies were not randomized clinical trials, and results can be countered by a number of biases prevalent in the studies, indicating the need for additional well-designed investigations to resolve remaining issues.

Bias↗