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Biomedical subjects

A Laupacis

Publications and source records attributed to A Laupacis.

At least 91 records · Page 5Linked to original sources
PubMed1996

Preventive therapies: weighing the pros and cons.

The author comments on three issues raised by Dr. Kenneth G. Marshall in his series on the benefits and harms of preventive therapies, which begins in this issue on page 1493. First, because the method by which the results of clinical trials are presented markedly affects the perception of those results some measure of absolute benefit and harm must be used when the results of clinical trials are presented. Second, there is increasing interest in decision aids as a means of helping patients to understand evidence and make therapeutic choices. It is important that these aids undergo rigorous testing before they are adopted for common use. Third, evidence-based clinical practice guidelines are a welcome resource for busy clinicians. However, physicians and patients should bear in mind that interpretations of the available evidence can vary, leading to different conclusions about the appropriateness of preventive therapies.

Clinical Trials as Topic↗
PubMed1996

The Ontario trial of active compression-decompression cardiopulmonary resuscitation for in-hospital and prehospital cardiac arrest.

OBJECTIVE: To compare the impact of active compression-decompression (ACD) cardiopulmonary resuscitation (CPR) and standard CPR on the outcomes of in-hospital and prehospital victims of cardiac arrest. DESIGN: Randomized controlled trial with blinding of allocation using a sealed container. SETTINGS: (1) Emergency departments, wards, and intensive care units of 5 university hospitals and (2) all locations outside hospitals in 2 midsized cities. PATIENTS: A total of 1784 adults who had cardiac arrest. INTERVENTION: Patients received either standard or ACD CPR throughout resuscitation. MAIN OUTCOME MEASURES: Survival for 1 hour and to hospital discharge and the modified Mini-Mental State Examination (MMSE). RESULTS: All characteristics were similar in the standard and ACD CPR groups for the 773 in-hospital patients and the 1011 prehospital patients. For in-hospital patients, there were no significant differences between the standard (n = 368) and ACD (n = 405) CPR groups in survival for 1 hour (35.1% vs 34.6%; P = .89), in survival until hospital discharge (11.4% vs 10.4%; P = .64), or in the median MMSE score of survivors (37 in both groups). For patients who collapsed outside the hospital, there were also no significant differences between the standard (n = 510) and ACD (n = 501) CPR groups in survival for 1 hour (16.5% vs 18.2%; P = .48), in survival to hospital discharge (3.7% vs 4.6%; P = .49), or in the median MMSE score of survivors (35 in both groups). Exploration of clinically important subgroups failed to identify any patients who appeared to benefit from ACD CPR. CONCLUSIONS: ACD CPR did not improve survival or neurologic outcomes in any group of patients with cardiac arrest.

Adolescent↗
PubMed1996

Randomised study of n of 1 trials versus standard practice.

OBJECTIVE: To compare outcomes between groups of patients with irreversible chronic airflow limitation given theophylline by n of 1 trials or standard practice. DESIGN: Randomised controlled study of n of 1 trials versus standard practice. SETTING: Tertiary care center outpatient department. SUBJECTS: 31 patients with irreversible chronic airflow limitation who were unsure that theophylline was helpful after an open trial. INTERVENTIONS: n Of 1 trials (single patient randomised multiple crossover comparisons of theophylline against placebo) followed published guidelines. For standard practice patients theophylline was stopped and resumed if their dyspnoea worsened; if their dyspnoea then improved theophylline was continued. For both groups a decision to continue or stop the drug was made within three months of randomisation. MAIN OUTCOME MEASURES: Exercise capacity as measured by six minute walking distance, quality of life as measured by the chronic respiratory disease questionnaire at baseline and six months after randomisation, and proportions of patients taking theophylline at six months. RESULTS: 26 patients completed follow up. 47% fewer n of 1 trial patients than standard practice patients were taking theophylline at six months (5/14 versus 10/12; 95% confidence interval of difference 14% to 80%) without differences in exercise capacity or quality of life. CONCLUSIONS: n Of 1 trials led to less theophylline use without adverse effects on exercise capacity or quality of life in patients with irreversible chronic airflow limitation. These data directly support the presence of a clinically important bias towards unnecessary treatment during open prescription of theophylline for irreversible chronic airflow limitation. Confirmation in a larger study and similar studies for other problems appropriate for n of 1 trials are needed before widespread use of n of 1 trials can be advocated in routine clinical practice.

Aged↗
PubMed1996

Effectiveness of emergency medical services for victims of out-of-hospital cardiac arrest: a metaanalysis.

STUDY OBJECTIVE: To determine the relative effectiveness of differences in response time interval, proportion of bystander CPR, and type and tier of emergency medical services (EMS) system on survival after out of hospital cardiac arrest. METHODS: We performed a comprehensive literature search, excluding EMS systems other than those of interest (systems of interest were those comprising one tier with providers of basic life support [BLS] or advanced life support [ALS] and those comprising two tiers with providers of BLS or BLS-defibrillation followed by ALS), patient population of fewer than 100 cardiac arrests, studies in which we could not determine the total number of arrests of presumed cardiac origin, and studies lacking data on survival to hospital discharge. Metaanalysis using generalized linear model with dispersion estimation for random effects was then performed. RESULTS: Increased survival to hospital discharge was significantly associated with tier (P < .01), response time interval (P < .01), and bystander CPR (P = .04). A significant interaction was detected between response time interval and bystander CPR (P = .02). For the studies analyzed, survival was 5.2% in a one-tier EMS system or 10.5% in a two-tier EMS system. A 1-minute decrease in mean response time interval was associated with absolute increases in survival rates of .4% and .7% in a one-tier and two-tier EMS systems, respectively. CONCLUSION: Increased survival to hospital discharge may be associated with decreased response time interval and with the use of a two-tier EMS system as opposed to a one-tier system. The data available for this analysis were suboptimal. Policymakers need more methodologically rigorous research to have more reliable and valid estimates of the effectiveness of different EMS systems.

Cardiopulmonary Resuscitation↗
PubMed1996

Cost-effectiveness analysis of potential improvements to emergency medical services for victims of out-of-hospital cardiac arrest.

STUDY OBJECTIVE: To measure the incremental cost-effectiveness of various improvements to emergency medical services (EMS) systems aimed at increasing survival after out-of-hospital cardiac arrest. METHODS: We performed cost-effectiveness analysis based on (1) metaanalysis of effectiveness of the various EMS systems, (2) costing of each component of EMS systems, (3) modeling of the relationship between the proportion of cardiac arrest victims who receive CPR and the proportion of individuals trained, (4) modeling of the relationship between response time interval and the characteristics of the EMS system, (5) measurement of quality of life, and (6) decision analysis to combine the results of the first five components. RESULTS: The incremental cost-effectiveness ratio for a 48-second improvement in mean response time in a one-tier EMS system yielded by the addition of more EMS providers was $368,000 per quality-adjusted life year (QALY). For improved response time in a two-tier EMS system by the addition of more basic life support (BLS)/BLS-defibrillator (BLS-D) providers to the first tier, the ratio was $53,000 per QALY with pump vehicles or $159,000 per QALY with ambulances. Change from a one-tier EMS to a two-tier EMS system by the addition of initial BLS/BLS-D providers in pump vehicles as the first tier was associated with a cost per QALY of $40,000. Change from one-tier EMS to two-tier EMS by the addition of initial BLS/BLS-D providers in ambulances as the first tier was associated with a cost per QALY of $94,000. CONCLUSION: The most attractive options in terms of incremental cost-effectiveness were improved response time in a two-tier EMS system or change from a one-tier to a two-tier EMS system. Future research should be directed toward identification of the costs of instituting the first tier of a two-tier EMS system and identification of cost-effective methods of improving response time.

Cardiopulmonary Resuscitation↗
PubMed1996

A study of the quality of life and cost-utility of renal transplantation.

The objective of this study was to assess the cost-utility of renal transplantation compared with dialysis. To accomplish this, a prospective cohort of pre-transplant patients were followed for up to two years after renal transplantation at three University-based Canadian hospitals. A total of 168 patients were followed for an average of 19.5 months after transplantation. Health-related quality of life was assessed using a hemodialysis questionnaire, a transplant questionnaire, the Sickness Impact Profile, and the Time Trade-Off Technique. Fully allocated costs were determined by prospectively recording resource use in all patients. A societal perspective was taken. By six months after transplantation, the mean health-related quality of life scores of almost all measures had improved compared to pre-transplantation, and they stayed improved throughout the two years of follow up. The mean time trade-off score was 0.57 pre-transplant and 0.70 two years after transplantation. The proportion of individuals employed increased from 30% before transplantation to 45% two years after transplantation. Employment prior to transplantation [relative risk (RR) = 23], graft function (RR 10) and age (RR 1.6 for every decrease in age by one decade), independently predicted employment status after transplantation. The cost of pre-transplant care ($66,782 Can 1994) and the cost of the first year after transplantation ($66,290) were similar. Transplantation was considerably less expensive during the second year after transplantation ($27,875). Over the two years, transplantation was both more effective and less costly than dialysis. This was true for all subgroups of patients examined, including patients older than 60 and diabetics. We conclude that renal transplantation was more effective and less costly than dialysis in all subgroups of patients examined.

Adult↗
PubMed1996

Prognosis of individuals with atrial fibrillation.

Patients with AF have a mortality rate about twice that of age-and sex-matched individuals without AF, and a stroke rate that is about fivefold greater. Patients less than 60 years of age with lone AF have an extremely low risk of stroke. Patients less than 65 years of age who do not have diabetes, a history of hypertension, a previous TIA or stroke, or heart failure have an annual risk of stroke of about 1% per year. Unfortunately, patients older than 65 or younger patients with any of the four risk factors have an annual risk of stroke of 4% or greater. Transthoracic and transesophageal echocardiography may be able to refine the risk stratification further, but additional studies are needed to establish their role.

Age Distribution↗
PubMed1996

The frequency of venous thrombosis in cemented and non-cemented hip arthroplasty.

We randomised 250 patients undergoing unilateral, elective hip arthroplasty for osteoarthritis to receive either a cemented or a non-cemented Mallory Head prosthesis. Aspirin was used as prophylaxis against thromboembolism during the first half of the study and adjusted-dose warfarin during the second half. Postoperatively, all patients were asked to have bilateral venography and 80% agreed. All were evaluated clinically for pulmonary embolism. There was no difference in the frequency of deep-venous thrombosis between the two groups (50% cemented nu 47% non-cemented, p = 0.73; 95% CI of the difference -13.6% to 19.3%). Three of the 64 patients (5%) in whom venography had demonstrated isolated distal thrombi developed pulmonary emboli.

Aged↗
PubMed1996

Effectiveness of perioperative epoetin alfa in patients scheduled for elective hip surgery.

Several strategies have been investigated as a means of reducing allogeneic blood requirements in patients undergoing surgery, including the perioperative administration of epoetin alfa. In a multicenter, double-blind, placebo-controlled study in 208 patients undergoing elective hip replacement surgery, subcutaneous administration of epoetin alfa (300 IU/kg daily) for 14 or 9 days perioperatively (commencing 10 and 5 days preoperatively, respectively) significantly reduced the incidence of primary outcome events (any allogeneic blood transfusion or a postoperative hemoglobin [Hb] level < 8.0 g/dL) compared with placebo (P = .003). Furthermore, the transfusion requirements of epoetin alfa-treated patients were significantly lower than those of patients treated with placebo (P = .007). Preoperative and postoperative Hb levels and reticulocyte counts were higher in epoetin alfa-treated patients compared with placebo. Epoetin alfa was well tolerated, and the incidence of deep vein thrombosis (DVT) was not different from that observed in placebo recipients. Thus, perioperative administration of epoetin alfa reduces the allogeneic blood requirements of patients undergoing elective hip replacement surgery and is of particular benefit in the subgroup of patients whose baseline Hb levels are less than 13.5 g/dL.

Anemia↗
PubMed1996

The Nicolas Andry award: comparative results of cemented and cementless total hip arthroplasty.

A prospective randomized clinical trial comparing cemented to cementless total hip arthroplasty has been ongoing at the author's institution since 1987. All parameters assessed showed that there was no statistically significant difference in any of the health related quality of life measures used when patients with cement were compared with patients without cement at any of the followup periods as many as 4 years later. The improvement was dramatic and sustained. No components (cemented or cementless) have been revised to date (average, 4.8 years). A radiographic analysis showed probable loosening of the cemented socket in 24% and presumed minimal pelvic osteolysis in 8%. The cementless sockets showed a greater frequency and severity of pelvic osteolysis (14%). The cemented femoral component was judged to be possibly loose in 10%; however, none were considered probably loose. The patients who had cementless femoral components were doing extremely well with the components showing very little subsidence or proximal stress protection noted. Osteolysis on the femoral side was not seen in any of the cementless stems. Total hip replacement gives comparable clinical results when health related quality of life measures are analyzed; however, metal backed cemented acetabular components have a high rate of radiographic failure. Short-term stability of a non-cemented porous coated titanium stem, however, gave excellent clinical and radiographic results.

Aged↗
PubMed1996

Selective screening for abdominal aortic aneurysm.

Abdominal aortic aneurysm (AAA) meets the criteria as a possible target for early detection by screening or case-finding, although the effectiveness of such an intervention has not yet been demonstrated. The purpose of this study was to estimate the increase in cost-effectiveness that would result from selectively screening individuals based on their risk of AAA. Data from a hospital-based case-control study involving 78 men with AAA (unruptured) and 99 male controls were used to derive a risk function based on age, cigarette smoking, high blood pressure, history of heart disease, body mass index and serum high-density lipoprotein, using logistic regression analysis. For each of the control subjects (assumed to be a representative sample of the general population of elderly men), the risk of AAA was estimated and multiplied by the expectation of life to give a measure of the potential benefit of screening. The proportion of the total potential benefit that would be obtained by screening only those with a given level of risk was estimated, and this was related to the proportion of the population screened. In order to obtain 80% of the total potential benefit among men, we found that it would be necessary to examine 52% of the elderly male population if using a risk function based on age alone; 35% would have to be screened if age and smoking were included; and 17% would require screening if all the risk factors were included. Selective screening for AAA appears to be a promising strategy, but a prospective study is required to demonstrate that the predictions are valid.

Aged↗
PubMed1995

Multicentre trial to introduce the Ottawa ankle rules for use of radiography in acute ankle injuries. Multicentre Ankle Rule Study Group.

OBJECTIVE: To assess the feasibility and impact of introducing the Ottawa ankle rules to a large number of physicians in a wide variety of hospital and community settings over a prolonged period of time. DESIGN: Multicentre before and after controlled clinical trial. SETTING: Emergency departments of eight teaching and community hospitals in Canadian communities (population 10,000 to 3,000,000). SUBJECTS: All 12,777 adults (6288 control, 6489 intervention) seen with acute ankle injuries during two 12 month periods before and after the intervention. INTERVENTION: More than 200 physicians of varying experience were taught to order radiography according to the Ottawa ankle rules. MAIN OUTCOME MEASURES: Referral for ankle and foot radiography. RESULTS: There were significant reductions in use of ankle radiography at all eight hospitals and within a priori subgroups: for all hospitals combined 82.8% control v 60.9% intervention(P < 0.001); for community hospitals 86.7% v 61.7%; (P < 0.001); for teaching hospitals 77.9% v 59.9%; (P < 0.001); for emergency physicians 82.1% v 61.6%; (P < 0.001); for family physicians 84.3% v 60.1%; (P < 0.001); and for housestaff 82.3% v 60.1%; (P < 0.001). Compared with patients without fracture who had radiography during the intervention period those who had no radiography spent less time in the emergency department (54.0 v 86.9 minutes; P < 0.001) and had lower medical charges ($70.20 v $161.60; P < 0.001). There was no difference in the rate of fractures diagnosed after discharge from the emergency department (0.5 v 0.4%). CONCLUSIONS: Introduction of the Ottawa ankle rules proved to be feasible in a large variety of hospital and community settings. Use of the rules over a prolonged period of time by many physicians of varying experience led to a decrease in ankle radiography, waiting times, and costs without an increased rate of missed fractures. The multiphase methodological approach used to develop and implement these rules may be applied to other clinical problems.

Ankle Injuries↗
PubMed1995

Research by collaboration.

Explore the source record for details and available documents.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1995

Prevalence, age distribution, and gender of patients with atrial fibrillation. Analysis and implications.

The prevalence of atrial fibrillation (AF) is related to age. Anticoagulation is highly effective in preventing stroke in patients with AF, but the risk of hemorrhage may be increased in older patients. We reviewed the available epidemiologic data to define the age and sex distribution of people with AF. From four large recent population-based surveys, we estimated the overall age- and gender-specific prevalence of AF. These estimates were applied to the recent US census data to calculate the number of men and women with AF in each age group. There are an estimated 2.2 million people in the United States with AF, with a median age of about 75 years. The prevalence of AF is 2.3% in people older than 40 years and 5.9% in those older than 65 years. Approximately 70% of individuals with AF are between 65 and 85 years of age. The absolute number of men and women with AF is about equal. After age 75 years, about 60% of the people with AF are women. In contrast to people with AF in the general population, patients with AF in recent anticoagulation trials had a mean age of 69 years, and only 20% were older than 75 years. The risks and benefits of antithrombotic therapy in older individuals are important considerations in stroke prevention in AF.

Adult↗
PubMed1995

Cost-effectiveness analysis of the Ottawa Ankle Rules.

STUDY OBJECTIVE: To conduct an incremental cost-effectiveness analysis of implementation of the Ottawa Ankle Rules in emergency departments in the United States and Canada. DESIGN: A decision analytic approach to technology assessment. Clinical decision rules that allow physicians to be more selective in their use of radiography were compared with current practice in a decision analytic model. SETTING: A university hospital adult ED. PARTICIPANTS: ED physicians instructed in the use of the Ottawa Ankle Rules for adult patients with ankle injury. RESULTS: Radiography, waiting time, lost productivity, and medicolegal costs were calculated. In the United States, the savings varied between US$614,226 and US$3,145,910 per 100,000 patients, depending on the charge rate for radiography. In Ontario, Canada, the total savings were CAN$730,145 per 100,000 patients. One- and two-way sensitivity analyses that varied the rate of missed fractures, cost of radiography, probability of lawsuits, and cost of lawsuits did not change the results substantially. CONCLUSION: Implementation of the Ottawa Ankle Rules would result in significant savings of health care dollars despite the cost of missed fractures including litigation costs.

Adult↗