Platelet-rich plasmapheresis in cardiac surgery: a meta-analysis of the effect on transfusion requirements

OBJECTIVE

Our purpose was to determine whether intraoperative platelet-rich plasmapheresis in cardiac surgery is effective in reducing the proportion of patients exposed to allogeneic red cell transfusions.

METHODS

A systematic search for prospective, randomized trials of platelet-rich plasmapheresis in cardiac surgery, using MEDLINE, HEALTHSTAR, Current Contents, "Biological Abstracts," and EMBASE/Excerpta Medica up to August 1997, was completed. Trials were included if they reported either the proportion of patients exposed to allogeneic red cells or the units of allogeneic red cells transfused. Trials were abstracted by 2 independent investigators and the quality of trial design was assessed with the use of a validated scale.

RESULTS

Seventeen references met the inclusion criteria (1369 patients [675 control: 694 platelet-rich plasmapheresis]). Platelet-rich plasmapheresis reduced the likelihood of exposure to allogeneic red cells in cardiac surgery (odds ratio 0.44; 95% confidence interval 0.27, 0.72, P = .001). Platelet-rich plasmapheresis had a small but statistically significant effect on both the volume of blood lost in the first 24 hours (weighted mean difference -102 mL; 95% confidence interval -148, -55 mL, P < .0001) and the mean units transfused (weighted mean difference -0.33 units; 95% confidence interval -0.43, -0.23, P < .0001). However, platelet-rich plasmapheresis was only marginally effective (odds ratio 0.83, 95% confidence interval 0.34, 2.01, P = .68) for "good" quality trials, whereas it appeared very effective in trials with poor methodologic quality (odds ratio 0.33, 95% confidence interval 0.17, 0.62, P = .0007).

CONCLUSIONS

Although platelet-rich plasmapheresis appeared effective in decreasing the proportion of patients receiving transfusions after cardiac operations, the quality of most of the supporting trials was low and the benefit was small in trials of good quality. Further clinical trials should be completed.

How interested is the public in genetic testing for colon cancer susceptibility? Report of a cross-sectional population survey

OBJECTIVE

To assess the public's interest in genetic testing for colon cancer susceptibility, to determine whether provision of information about the accuracy of the test or the population risk of inheriting the colon cancer gene influences interest, to determine the reasons for wanting to be tested and to identify the factors related to interest in testing.

DESIGN

A cross-sectional random digit dialing telephone survey of 501 adults.

SETTING

Ontario.

MAIN OUTCOME MEASURES

Proportion of the public interested in genetic testing; reasons for interest in testing.

RESULTS

Of the sample, 39.9% (95% confidence interval [CI] 35.5 to 44.3) stated that they would be very interested in taking a simple blood test if a positive result suggested they had an 80% chance of getting colon cancer sometime during their lifetime. When it was suggested that the test might be accurate only 90% of the time, 33.1% of the sample (95% CI 28.7 to 37.5) still said they would be very interested in testing. When informed that less than 1% of the population inherits the gene for colon cancer, the proportion of the sample stating they would still be very interested in genetic testing fell to 19.2% (95% CI 14.8 to 23.6). The main reasons given for wanting genetic testing were to take preventive action, for peace of mind and curiosity. For respondents who remained interested in testing after being given information about the population risk of inheriting the gene, 2 factors were identified by logistic regression analysis as being independently related to interest: worry about cancer and perceived risk of getting colon cancer.

CONCLUSIONS

If the public's interest in testing for colon cancer susceptibility has any influence on its eventual request to be tested, then demand for genetic testing may be considerable once such tests become widely available and known to the public. This study reveals that the public's interest in genetic testing is substantial, although modifiable by the provision of information about the population risk of inheriting a colon cancer gene. This finding suggests that genetic researchers and others should be careful to provide the population risk of inheriting cancer genes when discussing the discovery of these genes with the media. Furthermore, public health educators will need to ensure that information aids include material on familial risk criteria, genetic counselling and genetic testing, as well as on the implications of genetic testing, the general population risk of developing colon cancer and the general population risk of carrying the colon cancer gene. This information should also be provided to those who seek assessment, to health care professionals and to the public.

Preoperative autologous donation decreases allogeneic transfusion but increases exposure to all red blood cell transfusion: results of a meta-analysis. International Study of Perioperative Transfusion (ISPOT) Investigators

BACKGROUND

Concern about risks associated with allogeneic red blood cell transfusion has led to interest in methods of decreasing patient exposure to perioperative transfusion.

OBJECTIVE

To perform a meta-analysis to determine the degree to which predonation of autologous blood reduces patients' exposure to allogeneic blood and all transfusions of red blood cells (allogeneic or autologous).

METHODS

We searched MEDLINE, EMBASE, bibliographies, annual reports, press releases, newsletters from organizations with interests in the blood system, and personal files for randomized studies and concurrent control cohort studies in which the control groups were patients excluded for nonmedical reasons.

RESULTS

Patients who predonated autologous blood were less likely to receive allogeneic blood in the 6 randomized studies (n = 933) (odds ratio [OR], 0.17; 95% confidence interval [CI], 0.08-0.32) and in the 9 cohort studies (n = 2351) (OR, 0.19; 95% CI, 0.14-0.26). However, autologous donors were more likely to undergo transfusion with allogeneic and/or autologous blood (for randomized studies: OR, 3.03; 95% CI, 1.70-5.39 and for cohort studies: OR, 12.32; 95% CI, 5.90-25.40). Studies that reported use of transfusion protocols found less benefit with preoperative autologous donation, although the difference was not statistically significant.

CONCLUSIONS

Preoperative autologous donation of blood decreases exposure to allogeneic blood but increases exposure to any transfusion (allogeneic and/or autologous). There is a direct relationship between the transfusion rate in the control group and the benefit derived from preoperative autologous donation. This suggests that other methods of decreasing blood transfusion, such as surgical technique and transfusion protocols, may be as important as preoperative autologous donation of blood.

Perioperative allogeneic blood transfusion does not cause adverse sequelae in patients with cancer: a meta-analysis of unconfounded studies

BACKGROUND

There is controversy over whether perioperative allogeneic red blood cell transfusions are associated with an increased risk of cancer recurrence, postoperative infection or death in patients with cancer undergoing surgery.

METHODS

A systematic meta-analysis was performed to answer this question. Studies were identified from electronic databases (Medline 1966-1997, Cancerlit 1983-1997, Current Contents, Cinahl 1982-1996, Healthstar 1990-1997, Bioabstracts 1990-1996 and Embase), by hand search of the bibliographies of identified studies and relevant journals, and by contact with experts in the field. All randomized controlled trials or prospective cohort studies with active comparator controls (autologous or leucocyte-depleted allogeneic blood) were eligible for inclusion if they reported on mortality, infection or recurrence rate in patients with cancer undergoing potentially curative surgical resection. The validity of the identified studies was assessed by means of a standardized scale, and data abstraction was carried out by two investigators independently. A random effects model was used for data synthesis.

RESULTS

Of the 2172 references identified, only 17 studies fulfilled the inclusion criteria. After exclusion of duplicate publications, six randomized controlled trials and two prospective cohort studies with appropriate concurrent controls were included in the analysis. The summary risk ratios were 0.95 (95 per cent confidence interval (c.i.) 0.79-1.15) for all-cause mortality and 1.06 (95 per cent c.i. 0.88-1.28) for cancer recurrence, the two endpoints that were appropriate to combine statistically. There was significant heterogeneity (explainable by differences in study design and patient characteristics) in the postoperative infection data and the summary risk ratio was 1.00 (95 per cent c.i. 0.76-1.32) for the four studies that were appropriate to subject to meta-analysis. Given the sample sizes of these eight studies, this meta-analysis had insufficient power to detect a relative difference of less than 20 per cent in the frequency of death, cancer recurrence or infection between the allogeneic and control transfusion arms.

CONCLUSION

Although more studies are required before a definitive statement can be made, at this time there is no evidence that allogeneic blood transfusion increases the risk of clinically important adverse sequelae in patients with cancer undergoing surgery.

Emergency physicians' attitudes toward and use of clinical decision rules for radiography

OBJECTIVES

1) To assess Canadian emergency physicians' (EPs') use of and attitudes toward 2 radiographic clinical decision rules that have recently been developed and to identify physician characteristics associated with decision rule use; 2) to determine the use of CT head and cervical spine radiography by EPs and their beliefs about the appropriateness of expert recommendations supporting the routine use of these radiographic procedures; and 3) to determine the potential acceptance of clinical decision rules for CT scan in patients with minor head injury and cervical spine radiography in trauma patients.

METHODS

A cross-sectional anonymous mail survey of a random sample of 300 members of the Canadian Association of Emergency Physicians using Dillman's Total Design Method for mail surveys.

RESULTS

Of 288 eligible physicians, 232 (81%) responded. More than 95% of the respondents stated they currently used the Ottawa Ankle Rules and were willing to consider using the newly developed Ottawa Knee Rule. Physician characteristics related to frequent use of the Ottawa Ankle Rules were younger age, fewer years since graduating from medical school, part time or resident employment status, working in a hospital without a CT scanner, and believing that decision rules are not oversimplified cookbook medicine or too rigid to apply. Eighty-five percent did not agree that all patients with minor head injuries should receive a CT head scan and only 3.5% stated they always refer such patients for CT scan. Similarly, 78.5% of the respondents did not agree that all trauma patients should receive cervical spine radiography and only 13.2% said they always refer such patients for cervical spine radiography. Ninety-seven and 98% stated they would be willing to consider using well-validated decision rules for CT scan of the head and cervical spine radiography, respectively. Fifty-two percent and 67% of the respondents required the proposed CT and C-spine to be 100% sensitive for identifying serious injuries, respectively.

CONCLUSIONS

Canadian EPs are generally supportive of clinical decision rules and, in particular, have very positive attitudes toward the Ottawa Ankle and Knee Rules. Furthermore, EPs disagree with recommendations for routine use of CT head and cervical spine radiography and strongly support the development of well-validated decision rules for the use of CT head and cervical spine radiography. Most EPs expected the latter rules to be 100% sensitive for acute clinically significant lesions.

Does acute normovolemic hemodilution reduce perioperative allogeneic transfusion? A meta-analysis. The International Study of Perioperative Transfusion

The objective of this study was to systematically review the literature and to statistically summarize the evidence evaluating acute normovolemic hemodilution (ANH). Prospective, randomized, controlled trials of ANH that reported either the proportion of patients exposed to allogeneic blood or the units of allogeneic blood transfused were included. All types and languages of publication were eligible. Of 1573 identified publications, 24 trials (containing a total of 1218 patients) were included in the meta-analysis. When all trials were pooled, ANH reduced the likelihood of exposure to allogeneic blood (odds ratio [OR] 0.31, 95% confidence interval [CI] 0.15, 0.62) and the total units of allogeneic blood transfused (weighted mean difference [WMD] -2.22 U, 95% CI -3.57, -0.86). However, there was marked heterogeneity of the results. In trials using a protocol to guide perioperative transfusion, ANH failed to reduce either the likelihood of transfusion (OR 0.64, 95% CI 0.31, 1.31) or the units administered (WMD -0.25 U, 95% CI -0.60, 0.10). Adverse events were incompletely reported. It is possible that biased experimental design is, in part, responsible for the reported efficacy of this technique.

IMPLICATIONS

after a systematic literature review, 24 randomized trials examining the role of acute normovolemic hemodilution were identified, pooled, and summarized using statistical techniques. Many studies reported an impressive reduction in blood transfused. Closer examination suggests that these reductions in blood exposure may be due to flawed study design.

Towards a better yardstick: the choice of treatment thresholds in hypertension

In the past decade, enthusiasm for risk-based guidelines for the treatment of hypertensive patients, in which absolute risk profiles and individualized treatment strategies are employed, has steadily increased. This stems from the recognition that hypertension is only one of the risk factors for cardiovascular disease, and that the risk of morbidity or mortality in patients with mild hypertension depends more on their constellation of risk factors than on their actual blood pressure reading. While risk-based guidelines do offer some advantages over traditional guidelines, they also have important shortcomings that should be acknowledged. In particular, the use of risk-based guidelines does not obviate the need to set treatment thresholds. This is the key issue in any guideline because the treatment threshold determines the proportion of the population who will require treatment, the total cost of treatment, the number needed to treat to prevent one adverse event and the cost effectiveness of medical care. The advantages and shortcomings of risk-based guidelines are discussed and a method is proposed whereby the preferences of patients, practicing physicians, and the general public can be determined and incorporated into future hypertension guidelines.

Drugs to minimize perioperative blood loss in cardiac surgery: meta-analyses using perioperative blood transfusion as the outcome. The International Study of Peri-operative Transfusion (ISPOT) Investigators

Concern about the side effects of allogeneic red blood cell transfusion has increased interest in methods of minimizing perioperative transfusion. We performed meta-analyses of randomized trials evaluating the efficacy and safety of aprotinin, desmopressin, tranexamic acid, and epsilon-aminocaproic acid in cardiac surgery. All identified randomized trials in cardiac surgery were included in the meta-analyses. The primary outcome was the proportion of patients who received at least one perioperative allogeneic red cell transfusion. Sixty studies were included in the meta-analyses. The largest number of patients (5808) was available for the meta-analysis of aprotinin, which significantly decreased exposure to allogeneic blood (odds ratio [OR] 0.31, 95% confidence interval [CI] 0.25-0.39; P < 0.0001). The efficacy of aprotinin was not significantly different regardless of the type of surgery (primary or reoperation), aspirin use, or reported transfusion threshold. The use of aprotinin was associated with a significant decrease in the need for reoperation because of bleeding (OR 0.44, 95% CI 0.27-0.73; P = 0.001). Desmopressin was not effective, with an OR of 0.98 (95% CI 0.64-1.50; P = 0.92). Tranexamic acid significantly decreased the proportion of patients transfused (OR 0.50, 95% CI 0.34-0.76; P = 0.0009). Epsilon-aminocaproic acid did not have a statistically significant effect on the proportion of patients transfused (OR 0.20, 95% CI 0.04-1.12; P = 0.07). There were not enough patients to exclude a small but clinically important increase in myocardial infarction or other side effects for any of the medications. We conclude that aprotinin and tranexamic acid, but not desmopressin, decrease the number of patients exposed to perioperative allogeneic transfusions in association with cardiac surgery.

IMPLICATIONS

Aprotinin, desmopressin, tranexamic acid, and epsilon-aminocaproic acid are used in cardiac surgery in an attempt to decrease the proportion of patients requiring blood transfusion. This meta-analysis of all published randomized trials provides a good estimate of the efficacy of these medications and is useful in guiding clinical practice. We conclude that aprotinin and tranexamic acid, but not desmopressin, decrease the exposure of patients to allogeneic blood transfusion perioperatively in relationship to cardiac surgery.

A survey of management practices for isolated systolic hypertension

OBJECTIVE

To determine the management practices of clinicians for patients with isolated systolic hypertension, with particular attention to treatment thresholds, medication choices, and target blood pressures.

DESIGN

Self-administered questionnaire.

SETTING

Edmonton, Alberta, a large Canadian city.

PARTICIPANTS

A random sample of 348 family physicians and 125 internists.

MEASUREMENTS

Demographics of the respondents, first and second choice of antihypertensives, treatment thresholds, and target blood pressures for patients with isolated systolic hypertension.

RESULTS

Excluding 54 nondeliverable questionnaires, a response rate of 67% (281 surveys) was obtained. The responding clinicians reported treatment thresholds and target blood pressures consistent with the evidence from randomized clinical trials and the recommendations of the Canadian Hypertension Society and the Fifth Report of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure. Thiazide diuretics were recommended as first line therapy by 74% of internists and 58% of family physicians. Angiotensin converting enzyme inhibitors were the most frequently chosen second line drug (27% of internists and 45% of family physicians).

CONCLUSIONS

The reported management practices of this group of clinicians are consistent with the evidence from randomized clinical trials and the recommendations of national consensus guidelines.

Variation in ED use of computed tomography for patients with minor head injury

STUDY OBJECTIVE

To determine the frequency of utilization, yield for brain injury, incidence of missed injury, and variation in the use of computed tomography (CT) for ED patients with minor head injury.

METHODS

This retrospective health records survey was conducted over a 12-month period in the EDs at seven Canadian teaching institutions. Included in this review were adult patients who sustained acute minor head injury, defined as witnessed loss of consciousness or amnesia and a Glasgow Coma Scale score of 13 or greater. Data were collected by research assistants who were trained to select cases and abstract data in a standardized fashion according to a resource manual. Subsequently, patient eligibility was reviewed by the study coordinator and principal investigator.

RESULTS

Of the 1,699 patients seen, 521 (30.7%) were referred for CT, and 418 (79.8%) of these scans were negative for any type of brain injury. Overall, 105 (6.2%) of these patients sustained acute brain injury, including 9 (.5%) with an epidural hematoma Cochran's Q test for homogeneity demonstrated significant variation between the seven centers for rate of ordering CT (P < .0001), from a low of 15.9% to a high of 70.4%. All five cases of "missed" hematoma occurred at the institutions with the highest and third highest rates of CT use. After controlling for possible differences in case severity and patient characteristics at each hospital, logistic regression analysis revealed that five of seven hospitals were significantly associated with the use of CT (respected odds ratios [OR], .4, .5, .5, 3.2, and 4.7). Three of the centers (two with the highest ordering rates) showed significant heterogeneity in the ordering of CT among their attending staff physicians, from a low of 6.5% to a high of 80.0%.

CONCLUSION

There was considerable variation among institutions and individual physicians in the ordering of CT for patients with minor head injury. Although emergency physicians were selective when ordering CT, the yield of radiography was very low at all hospitals. None of the cases of "missed" intracranial hematoma came from the lowest ordering institutions, indicating that patients may be managed safely with a selective approach to CT use. These findings suggest great potential for more standardized and efficient use of CT of the head, possibly through the use of a clinical decision rule.

A survey of clinician attitudes and management practices in hypertension

In order to determine the compliance of Canadian physicians with evidence-based hypertension guidelines, a self-administered questionnaire survey was distributed to a stratified random sample of 473 physicians in Central Alberta, Canada in December 1995. Excluding non-deliverable questionnaires, a response rate of 67% was obtained. Twenty-five per cent of respondents routinely used the fourth Korotkoff sound to define diastolic blood pressure (DBP). Investigations recommended for the initial workup of a patient with mild hypertension included serum creatinine (90%), electrolytes (72%), glucose (50%), cholesterol (44%), electrocardiogram (65%), and urinalysis (76%). The non-pharmacologic treatment advice routinely advocated for patients with mild hypertension included salt restriction (87%), weight loss (100%), and regular aerobic exercise (92%). While 46% of respondents recommended antihypertensive therapy for an otherwise healthy patient with an average DBP of 95 mm Hg, 76% recommended therapy for patients with the same BP plus target organ damage or other cardiovascular risk factors. Medication choices varied, although angiotensin-converting enzyme inhibitors were chosen by 46% for patients with uncomplicated essential hypertension and 67% for patients with other cardiovascular risk factors, and beta-blockers were the most frequently chosen first-line agents (56%) for the patient with target organ damage. There was considerable variability in the self-reported practice patterns, and concordance was greater for those recommendations which were consistent across the currently available guidelines. Consistent with the principle underlying all of the current hypertension guidelines, respondents were more aggressive in their treatment of hypertensive patients with other cardiovascular risk factors or target organ damage.

Variation in emergency department use of cervical spine radiography for alert, stable trauma patients

OBJECTIVE

To, assess the emergency department use of cervical spine radiography for alert, stable adult trauma patients in terms of utilization, yield for injury and variation in practices among hospitals and physicians.

DESIGN

Retrospective survey of health records.

SETTING

Emergency departments of 6 teaching and 2 community hospitals in Ontario and British Columbia.

PATIENTS

Consecutive alert, stable adult trauma patients seen with potential cervical spine injury between July 1, 1994, and June 30, 1995.

MAIN OUTCOME MEASURES

Total number of eligible patients, referral for cervical spine radiography (overall, by hospital and by physician), presence of cervical spine injury, patient characteristics and hospitals associated with use of radiography.

RESULTS

Of 6855 eligible patients, cervical spine radiography was ordered for 3979 (58.0%). Only 60 (0.9%) patients were found to have an acute cervical spine injury (fracture, dislocation or ligamentous instability); 98.5% of the radiographic films were negative for any significant abnormality. The demographic and clinical characteristics of the patients were similar across the 8 hospitals, and no cervical spine injuries were missed. Significant variation was found among the 8 hospitals in the rate of ordering radiography (p < 0.0001), from a low of 37.0% to a high of 72.5%. After possible differences in case severity and patient characteristics at each hospital were controlled for, logistic regression analysis revealed that 6 of the hospitals were significantly associated with the use of radiography. At 7 hospitals, there was significant variation in the rate of ordering radiography among the attending emergency physicians (p < 0.05), from a low of 15.6% to a high of 91.5%.

CONCLUSIONS

Despite considerable variation among institutions and individual physicians in the ordering of cervical spine radiography for alert, stable trauma patients with similar characteristics, no cervical spine injuries were missed. The number of radiographic films showing signs of abnormality was extremely low at all hospitals. The findings suggest that cervical spine radiography could be used more efficiently, possibly with the help of a clinical decision rule.

Clinical prediction rules. A review and suggested modifications of methodological standards

BACKGROUND

Clinical prediction rules are decision-making tools for clinicians, containing variables from the history, physical examination, or simple diagnostic tests.

OBJECTIVE

To review the quality of recently published clinical prediction rules and to suggest methodological standards for their development and evaluation.

DATA SOURCES

Four general medical journals were manually searched for clinical prediction rules published from 1991 through 1994.

STUDY SELECTION

Four hundred sixty potentially eligible reports were identified, of which 30 were clinical prediction rules eligible for study. Most methodological standards could only be evaluated in 29 studies.

DATA ABSTRACTION

Two investigators independently evaluated the quality of each report using a standard data sheet. Disagreements were resolved by consensus.

DATA SYNTHESIS

The mathematical technique was used to develop the rule, and the results of the rule were described in 100% (29/29) of the reports. All the rules but 1 (97% [28/29]) were felt to be clinically sensible. The outcomes and predictive variables were clearly defined in 83% (24/29) and 59% (17/29) of the reports, respectively. Blind assessment of outcomes and predictive variables occurred in 41% (12/29) and 79% (23/29) of the reports, respectively, and the rules were prospectively validated in 79% (11/14). Reproducibility of predictive variables was assessed in only 3% (1/29) of the reports, and the effect of the rule on clinical use was prospectively measured in only 3% (1/30). Forty-one percent (12/29) of the rules were felt to be easy to use.

CONCLUSIONS

Although clinical prediction rules comply with some methodological criteria, for other criteria, better compliance is needed.

Warfarin for atrial fibrillation. The patient's perspective

OBJECTIVE

To determine the minimal clinically important difference (MCID) of warfarin therapy for the treatment of nonvalvular atrial fibrillation from the perspective of patients using 2 different elicitation methods.

DESIGN

All patients completed 2 face-to-face interviews, which were 2 weeks apart. For each interview, they were randomized to receive 1 of 2 elicitation methods: ping-ponging or starting at the known efficacy.

SETTING

The practices of 2 university-affiliated family medicine centers (8 physicians each), 14 community-based family physicians, and 2 cardiologists.

PATIENTS

Sixty-four patients with nonvalvular atrial fibrillation who were initiated with warfarin therapy at least 3 months before the study.

INTERVENTION

During each interview, the patients' MCIDs were determined by using (1) a pictorial flip chart to describe atrial fibrillation; the consequences of a minor stroke, a major stroke, and a major bleeding episode; the chance of stroke if not taking warfarin; the chance of a major bleeding episode if taking warfarin; examples of the inconvenience, minor side effects, and costs of warfarin therapy; and then (2) 1 of the 2 elicitation methods to determine their MCIDs (the smallest reduction in stroke risk at which the patients were willing to take warfarin). Patients' knowledge of their stroke risk, acceptability of the interview process, and factors determining their preferences were also assessed.

MAIN RESULTS

Given a baseline risk of having a stroke in the next 2 years, if not taking warfarin, of 10 of 100, the mean MCID was 2.01 of 100 (95% confidence interval, 1.60-2.42). Fifty-two percent of the patients would take warfarin for an absolute decrease in stroke risk of 1% over 2 years. Before eliciting their MCIDs, patients showed poor knowledge of their stroke risk, which improved afterward. The interview process was well accepted by the patients. The MCID using the ping-ponging elicitation method was 1.015 of 100 smaller compared with use of the starting at the known efficacy method (P = .01).

CONCLUSIONS

We were able to determine the MCID of warfarin therapy for the prevention of stroke from the perspective of patients with nonvalvular atrial fibrillation. Their MCIDs were much smaller than those that have been implied by some experts and clinicians. The interview process, using the flip chart approach, appeared to improve the patients' knowledge of their disease and its consequences and treatment. The method used to elicit the patients' MCIDs can have a clinically important effect on patient responses. The method used in our study can be generalized to other conditions and, thus, could be helpful in 3 ways: (1) from a clinical decision-making perspective, it could facilitate patient-physician communication; (2) it could clarify the patient perspective when interpreting the results of previously completed trials; and (3) it could be used to derive more clinically relevant sample sizes for randomized treatment trials.

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.

Canadian atrial fibrillation anticoagulation study: were the patients subsequently treated with warfarin? Canadian Atrial Fibrillation Anticoagulation Study Group

OBJECTIVE

To determine the effect of the results of clinical trials on the behaviour of patients and physicians, the authors ascertained the proportion of patients participating in the Canadian Atrial Fibrillation Anticoagulation (CAFA) study who started or continued warfarin therapy at the end of the study and identified factors affecting the decision to use or not use warfarin. The CAFA study was a double-blind, randomized, placebo-controlled, multicentre study to evaluate the efficacy of warfarin in preventing stroke among patients with nonrheumatic atrial fibrillation. Recruitment and follow-up were stopped early because two other similar studies had shown a decrease in the rate of stroke among patients treated with warfarin.

DESIGN

Mail survey 21 months after the end of the study.

PARTICIPANTS

The personal physicians of 336 patients who had participated in the CAFA study.

OUTCOME MEASURES

Type of antithrombotic therapy the patients had received since the CAFA study ended for patients who were not receiving warfarin, the reasons they were not.

RESULTS

Questionnaires concerning 254 (76%) of the patients who had participated in the study were returned. Since the end of the CAFA study, 153 (60%) of these patients had been treated continually with warfarin, 14 (6%) had been treated with warfarin but had subsequently stopped taking it, 59 (23%) had taken acetylsalicylic acid (ASA) continually, 5 (2%) had been taking ASA but had subsequently stopped taking it, and 23 (9%) had not taken either drug. The responding physicians stated that 58 (67%) of the patients who were not treated with warfarin did not wish to take the drug. The patients who had received warfarin during the CAFA trial were more likely to be treated with warfarin after the trial (75%) than were those who had received a placebo (56%) (p = 0.001). The probability of the patients' being treated with warfarin also depended on which study centre they had been treated in (p = 0.001).

CONCLUSIONS

Of the patients in the CAFA study for whom questionnaires were received, only 167 (66%) had been treated with warfarin after the end of the study. The patients were more likely to have been treated with warfarin after the study if they had received warfarin during the study. The positive results of clinical trials, on their own, are not enough to fully change the behaviour of patients and physicians.