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Biomedical subjects

C D Naylor

Publications and source records attributed to C D Naylor.

At least 73 records · Page 4Linked to original sources
PubMed1997

Use of cardiac procedures and outcomes in elderly patients with myocardial infarction in the United States and Canada.

BACKGROUND: Acute myocardial infarction is a leading cause of morbidity and mortality in the United States and Canada. We performed a population-based study to compare the use of cardiac procedures and outcomes after acute myocardial infarction in elderly patients in the two countries. METHODS: We compared the use of invasive cardiac procedures and the mortality rates among 224,258 elderly Medicare beneficiaries in the United States and 9444 elderly patients in Ontario, Canada, each of whom had a new acute myocardial infarction in 1991. RESULTS: The U.S. patients were significantly more likely than the Canadian patients to undergo coronary angiography (34.9 percent vs. 6.7 percent, P< 0.001), percutaneous transluminal coronary angioplasty (11.7 percent vs. 1.5 percent, P<0.001), and coronary-artery bypass surgery (10.6 percent vs. 1.4 percent, P<0.001) during the first 30 days after the index infarction. These differences in the use of cardiac procedures narrowed but persisted through 180 days of follow-up. The 30-day mortality rates were slightly but significantly lower for the U.S. patients than for the Canadian patients (21.4 percent vs. 22.3 percent, P=0.03). However, the one-year mortality rates were virtually identical (34.3 percent in the United States vs. 34.4 percent in Ontario, P= 0.94). CONCLUSIONS: Short-term mortality after an acute myocardial infarction was slightly lower in the United States than in Ontario, but these differences did not persist through one year of follow-up. The strikingly higher rates of use of cardiac procedures in the United States, as compared with Canada, do not appear to result in better long-term survival rates for elderly U.S. patients with acute myocardial infarction.

Aged↗
PubMed1997

Time to treatment with thrombolytic therapy: determinants and effect on short-term nonfatal outcomes of acute myocardial infarction. Canadian GUSTO Investigators. Global Utilization of Streptokinase and + PA for Occluded Coronary Arteries.

OBJECTIVES: To characterize the extent of delay in administration of thrombolytic therapy to patients with acute myocardial infarction (AMI) in Canada, to examine patient-specific predictors of such delay and to measure the effect of delay on short-term nonfatal cardiac outcomes. DESIGN: Secondary cohort analysis of data from the first international Global Utilization of Streptokinase and tPA for Occluded Coronary Arteries (GUSTO-I) trial. SETTING: Sixty-three acute care hospitals across Canada. SUBJECTS: All 2898 Canadian patients with an AMI enrolled in GUSTO-I. MAIN OUTCOMES: Time before arrival at a hospital ("symptom-to-door" time) and time from arrival to administration of therapy ("door-to-needle" time) for patients who had an AMI outside of a hospital, in clinically relevant categories; proportions of patients with nonfatal, serious cardiac events, including shock, sustained ventricular tachycardia, ventricular fibrillation and asystole. RESULTS: Of the total number of patients enrolled, records were complete for 2708; 2542 of these patients (93.9%) had an AMI outside of a hospital. These 2542 patients presented a median 81 (interquartile range 50 to 130) minutes after the onset of symptoms, and the median time to treatment in hospital was 85 (interquartile range 61 to 115) minutes. Whereas a greater proportion of Canadian patients than of patients enrolled in GUSTO-I in other countries reached hospital within 2 hours of symptom onset (71.5% v. 61.2%, p < 0.001), a greater proportion of Canadian patients experienced in-hospital treatment delays of more than 1 hour (75.3% v. 57.1%, p < 0.001). In an analysis of all 2708 patients with complete records, both the unadjusted and adjusted odds of nonfatal cardiac events for those treated 4 to 6 hours after symptom onset were significantly higher than for those treated within 2 hours (odds ratio 1.60, 95% confidence interval 1.09 to 2.37). CONCLUSION: After arrival at a hospital, Canadian patients enrolled in GUSTO-I received thrombolytic therapy more slowly than trial enrollees in other countries. Such delays are already known to decrease the rate of short-term survival after AMI. The findings further show that long time to treatment also increases the odds of nonfatal, serious cardiac events. Hospitals and physicians caring for patients with AMI should routinely assess whether and how they can improve door-to-needle times.

Adult↗
PubMed1997

Coronary artery bypass graft surgery in Ontario and New York State: which rate is right? Steering Committee of the Cardiac Care Network of Ontario.

BACKGROUND: Previous studies have shown that the rate of coronary artery bypass graft (CABG) surgery is much higher in New York State than in Ontario. OBJECTIVE: To compare the service context and clinical characteristics of patients having CABG surgery in New York and Ontario. DESIGN: Retrospective analysis of data from cardiac surgery registries in New York and Ontario. PATIENTS: All 16,690 patients in New York and 5517 patients in Ontario who had isolated CABG surgery in 1993. MEASUREMENTS: Clinical characteristics of patients having CABG surgery and rates of CABG surgery by coronary anatomy. RESULTS: The overall age-adjusted rate of isolated CABG surgery was 1.79 times (95% CI, 1.74 to 1.85) greater in New York than in Ontario. Patients who had CABG surgery in New York were more likely to be elderly and female and to have recently had myocardial infarction (P < 0.001), whereas patients who had CABG surgery in Ontario were more likely to have had left ventricular dysfunction and severe coronary artery disease (two-vessel disease with proximal left anterior descending disease, three-vessel disease, or left main disease) (P < 0.001). The relative rate of CABG surgery for left main disease was 2.53 times (CI, 2.35 to 2.73) greater in New York than in Ontario but was 8.97 times (CI, 8.01 to 10.06) greater for patients with limited coronary artery disease (one-vessel or two-vessel disease without proximal left anterior descending disease). CONCLUSIONS: The higher rates of CABG surgery in New York are associated with higher rates of CABG surgery among the elderly, women, and patients who recently had myocardial infarction. Potential underservicing in Ontario is suggested by a lower rate of CABG surgery for left main disease; however, the higher rate of CABG surgery in New York is also associated with a strikingly higher rate of surgery in patients with limited coronary disease. Such trade-offs highlight the difficulty of defining an optimal rate of CABG surgery.

Adult↗
PubMed1997

The influence of risk on the results of warm heart surgery: a substudy of a randomized trial.

OBJECTIVE: The Warm Heart Investigators Trial randomized isolated coronary bypass patients to cold or warm cardioplegia, and demonstrated that warm cardioplegia significantly reduced the prevalence of low output syndrome and myocardial infarction (as defined by CKMB enzyme release). This study was designed prospectively as a subanalysis of the original trial, to determine the effect of warm heart surgery on high risk patients, who were anticipated to derive the major benefit from warm cardioplegia. METHODS: The prespecified endpoint for this study was a composite outcome of morbidity and mortality (death and/or low output syndrome and/or enzymatic myocardial infarction). Only patients with complete data for all outcomes were included, totalling 1374 patients (692 warm cardioplegia, 682 cold cardioplegia) who were randomized in the Warm Heart Investigators Trial. High medium and low risk patients were identified by a multivariate model of predicted risk for the study outcome. RESULTS: Analysis of the independent and interactive influence of cardioplegia technique and predicted risk demonstrated that warm cardioplegia significantly reduced the overall prevalence of morbidity and mortality (warm: 15.9 versus cold: 25.2%, P < 0.01). However, no significant differences in warm-cold effects were detected among risk terciles. Cardioplegia technique had a similar differential influence on mortality and morbidity in low risk patients (warm: 7.3, cold: 17.4%) as it did in high risk patients (warm: 31.1, cold: 39.9%). CONCLUSIONS: Although our analysis confirms the overall benefits of warm cardioplegia, our unanticipated finding in high risk subjects may be explained by the fact that morbidity and mortality in that patient subgroup is caused not only by poor myocardial protection, but by other clinical and technical factors. Further studies are necessary to identify those patients who might benefit most from improved myocardial protection techniques.

Adult↗
PubMed1997

The HIV-specific advance directive.

OBJECTIVE: To determine whether persons living with HIV find a disease-specific advance directive more acceptable than a generic directive. DESIGN: Randomized clinical trial. SETTING: HIV consumer organization and hospital-based HIV clinic. PARTICIPANTS: Volunteer sample of persons with HIV. INTERVENTIONS: The disease-specific HIV Living Will, the generic Centre for Bioethics Living Will, or both. MEASUREMENTS AND MAIN RESULTS: Of 101 participants who received both advance directives, 78 (77.2%) preferred the disease-specific HIV Living Will and 23 (22.8%) preferred the generic Centre for Bioethics Living Will (p < .001). Most participants who preferred the HIV Living Will did so because it was more specific or relevant to their situation. CONCLUSIONS: Persons living with HIV prefer a disease-specific to a generic advance directive. They should be offered a disease-specific advance directive. Our findings should also encourage investigators to develop and evaluate disease-specific advance directives in other clinical settings.

Adult↗
PubMed1997

The burden of waiting for hip and knee replacements in Ontario. Ontario Hip and Knee Replacement Project Team.

The objectives of this study were to assess the impact of major joint replacements in reducing pain and disability and to describe the burden of pain and disability that could be avoided by ordering the queues with respect to severity of disease. A secondary goal was to compare the uses of a general health status measure, the Short Form Health Survey (SF-36), and a disease-specific measure, the Western Ontario McMaster Osteoarthritis Index (WOMAC), for accomplishing the objectives. The results are based on interviews with 209 patients before and after they had surgery. Only 15.9% of the patients had surgery within 3 months' waiting time, 19.2% waited 4-6 months, 30.7% waited 7-9 months, and the remaining 34.1% waited a year or more. The waiting times were unrelated to the severity of pain or disability reported in the initial interview. Following surgery, there were large reductions in the WOMAC scores for pain, stiffness and difficulty in functioning. The SF-36 showed substantial improvements in relief from pain and in physical functioning, and reductions in role limitation due to physical problems, but not for scores related to mental health. The WOMAC scores were more responsive to the benefits of surgery than the SF-36 scores. Queuing systems keyed on burden of symptoms could reduce the burden of pain and disability suffered by patients awaiting surgery. The improvements from hip and knee replacements suggest that equitable access for these procedures should be a priority in Ontario.

Aged↗
PubMed1997

Distributional dilemmas in health policy: large benefits for a few or smaller benefits for many?

OBJECTIVES: To examine funding priorities assigned by health ministry officials when choosing between clinical programs that offer similar overall benefits distributed in different ways (e.g. large gains for a few versus small gains for many), and to compare the relative magnitude of any distributional bias to age biases. METHODS: A survey consisting of paired hypothetical health care programs was mailed to the 135 most senior officials of the Health Ministry in Ontario, Canada (population 11.5 million). Respondents were asked to assume they were members of a panel allocating a fixed sum of money to one of two programs in each pair. All program descriptions included the number of persons affected each year by a given disease and the average survival gains from the hypothetical programs. Some scenarios also mentioned the side-effects associated with programs and/or the average age of the beneficiaries. RESULTS: Four respondents had retired/died. Of 131 eligible respondents, 80/131 (61%) provided usable responses. Asked to choose between providing large benefits to a few citizens and small benefits to a great many, 23% (95% CI: 14%, 33%) of respondents were unable to decide, but 55.8% (95% CI: 47%, 70%) favored providing large benefits to fewer patients. Eliminating the 23% unable to decide, 47/62 or 76% (CI 63%, 86% expressed a distributional preference. With a smaller distributional discrepancy, indecision increased, with 35% of respondents having no preference and the remainder split almost evenly between the two programs. Other scenarios showed that health officials' pro-youth biases were only slightly larger than their distributional preferences and that distributional preferences were magnified when combined with minor differences in average ages of beneficiaries. CONCLUSIONS: A substantial minority of health care decision-makers had difficulty choosing between programs with similar overall gains and distributional differences--a result consistent with the utilitarian assumptions of cost-effectiveness analysis. However, when distributional differences were large, decision-makers clearly favored large gains for a few beneficiaries rather than small gains for many. Policy analysts should explicitly weigh distributional issues along with aggregate health gains when addressing resources allocation problems.

Administrative Personnel↗
PubMed1997

Breast cancer patients' attitudes about rationing postlumpectomy radiation therapy: applicability of trade-off methods to policy-making.

PURPOSE: Along with evidence, clinical policies must take patients' values into account. Particularly where evidence is limited and where assumptions of utility-maximizing behavior may not be valid, new methods such as trade-off techniques (TOTs), which allow elicitation of patients' treatment alternatives, might be useful in policy formulation. We used TOTs to assess breast cancer patients' attitudes toward two clinical policies designed to ration adjuvant postlumpectomy breast radiation therapy. METHODS: Cross-sectional interviews were performed in a tertiary cancer center. A total of 102 patients were presented with information about the side effects and benefits associated with two hypothetical decisions: (1) willingness to receive treatment elsewhere to shorten the wait for radiation therapy, and (2) foregoing radiation therapy in the face of small marginal benefits. For each scenario, a TOT was used to identify the maximal acceptable wait time (MAWT) for therapy and the benefit threshold at which the patient would forego therapy. Associations of clinical and demographic factors with these decisions were determined by regression analysis. RESULTS: Patients would be willing to wait, on average, 7 weeks before wanting to leave their city for radiation therapy, less than the 13-week delay our patients actually faced. Older patients were less willing to wait (P = .013); 46% of patients would not give up radiation therapy, even in the face of no stated benefit. Willingness to give up radiation therapy was predicted by willingness to accept delay (odds ratio [OR], 1.84; 95% confidence interval [CI], 1.05 to 3.37) and being employed (OR, 2.61; 95% CI, 1.08 to 6.54). Patients with larger tumors were less willing to give up radiation therapy (OR, 0.57; 95% CI, 0.31 to 0.97). CONCLUSION: Even in difficult decisions such as rationing postlumpectomy breast cancer radiation therapy, TOTs can inform policy formulation by indicating the distributions of patients' preferences.

Adult↗
PubMed1997

Case selection and appropriateness of coronary angiography and coronary artery bypass graft surgery in British Columbia and Ontario.

OBJECTIVES: To compare the types of patients selected for coronary angiography (CA) and coronary artery bypass graft (CABG) surgery, and the appropriateness of the procedures performed on these patients in a random sample of cases in British Columbia and Ontario. DESIGN: Retrospective randomized medical record review. SETTING: All hospitals performing CA and/or CABG in British Columbia and Ontario in fiscal year 1989/90. PATIENTS: For CA, 395 randomly selected patients in Ontario and 139 randomly selected patients in British Columbia; for CABG, 431 randomly selected patients in Ontario and 125 randomly selected patients in British Columbia. MAIN OUTCOME MEASURES: Case selection was measured in terms of the demographic and clinical characteristics of patients undergoing the procedures. Appropriateness was measured by comparing the clinical characteristics of patients undergoing the procedures with explicit criteria established by a panel of Canadian physicians. The yield from CA was measured as the proportion of patients who were found to have insignificant anatomical disease. RESULTS: Analysis of patients selected for CA showed that sample patients from Ontario were less likely than those from British Columbia to be female (25% versus 37%, respectively, P = 0.012) and less likely to have undergone a previous revascularization (12% versus 24%, respectively, P = 0.005). The distribution of main indications for CA differed between the two provinces (P = 0.002), with Ontario patients more likely to have chronic stable angina (45% versus 24%) and less likely to have unstable angina (16% versus 26%). For CABG, sample patients from Ontario were less likely to be 65 years of age or older (32% versus 45%, P = 0.016) and more likely to have an ejection fraction less than 35% (14% versus 5%, P = 0.006). The distribution of the main indications for CABG differed (P < 0.001), with Ontario patients more likely to have chronic stable angina (68% versus 38%) and less likely to have unstable angina (20% versus 43%). There was no statistically significant difference in CA cases rated as inappropriate (8.4% in Ontario versus 10.8% in British Columbia, P = 0.396) or CABG cases rated as inappropriate (3.9% in Ontario versus 2.4% in British Columbia, P = 0.393). There were no statistically significant differences in the proportion of CA that yielded insignificant anatomical disease (17.5% in Ontario versus 18.4% in British Columbia, P = 0.355). CONCLUSIONS: There were differences between Ontario and British Columbia in the demographic and clinical characteristics of patients selected for CA and CABG. This may indicate differences in the referral process in the two provinces. Despite these differences the rates of inappropriate procedures and the yield from CA were similar.

Aged↗
PubMed1997

Is colour flow imaging needed to exclude clinically significant valvular regurgitation in adult patients undergoing transthoracic echocardiography?

OBJECTIVE: To establish whether clinically significant aortic and mitral valvular regurgitation can be excluded in adult patients undergoing transthoracic echocardiography without using colour flow imaging. SETTING: Sunnybrook Health Science Centre, a tertiary referral centre with full cardiovascular services affiliated with the University of Toronto, Toronto, Ontario. DESIGN: Logistic regression models were developed from a retrospective review of 14,051 unselected consecutive echocardiograms from 1991 through 1994. The dependent variable was more than mild aortic or mitral valvular regurgitation. Independent variables included age, sex and various functional and structural measures obtained during routine two-dimensional echocardiography. The negative predictive values and sensitivity of the models were estimated. INTERVENTION: The number of patients correctly classified by these models, as well as the proportion for whom the colour flow imaging did not add to the baseline echocardiogram, was determined. Nonparametric bootsrapping was used to obtain confidence intervals for these statistics. MAIN RESULTS: Ten models were developed, with negative predictive values ranging from 96.2% to 100%. Incorporation of such decision aids into the software of echocardiographic machinery would help echocardiographers to rule out significant aortic or mitral regurgitant lesions. In practices where colour flow imaging is routinely employed, 40% fewer procedures could be performed. CONCLUSIONS: Models based on simple demographic and two-dimensional echocardiographic variables can reliably exclude significant valvular regurgitation and could potentially reduce the volumes and costs of colour flow imaging. Given the widespread diffusion of colour Doppler imaging, the models may also be helpful to avoid misinterpretation of flow imaging results, by defining subgroups in whom the prior probability of significant aortic or mitral regurgitation is extremely low.

Aged↗
PubMed1997

Towards improved coding of acute myocardial infarction in hospital discharge abstracts: a pilot project.

OBJECTIVE: To pilot-test a simple checklist designed to improve coding of acute myocardial infarction (AMI) in hospital discharge abstracts. BACKGROUND: Health records technologists review hospital charts to code discharge diagnoses according to the International Classification of Diseases, 9th revision (ICD-9). Many studies have suggested that there is a high false positive rate in coding AMI, ie, ICD-9 410, on hospital discharge abstracts. PATIENTS AND METHODS: The checklist required either at least two of suggestive symptoms, diagnostic electrocardiographic changes, or diagnostic rise in serum cardiac enzymes; or confirmation by autopsy. First case of use was confirmed-typical time to complete the checklist was 3 to 4 mins. Then 16 Ontario community hospitals were recruited to apply the checklist on a blinded basis to 1000 randomly drawn in-patient records-10% were audited for another study to confirm AMI; and 90% were originally coded with 'most responsible diagnosis' (MRD) of AMI, other cardiovascular diagnoses and various noncardiac conditions. Percentage agreement (95% CI) between the checklist and the confirmed or coded diagnosis was analyzed; coding of AMI as a secondary diagnosis was examined in further analyses. RESULTS: One hospital withdrew for logistical reasons; the final useable sample from 15 hospitals was 943 records. The checklist correctly identified 100% of AMIs independently confirmed for another study; usual coding identified 89.7% of cases (70 of 78; 95% CI 80.8 to 95.5). For cases not confirmed, but where the physician had nonetheless diagnosed AMI, six of 11 charts were miscoded as AMI in hospital records; none were miscoded by the checklist. For records with AMI as MRD, 11.6% (44 of 380; 95% CI 8.5 to 15.2) were classified as false positives by the checklist. Where an AMI was coded as a secondary diagnosis, 52.9% (36 of 68; 95% CI 40.5 to 65.2) met the checklist criteria for AMI. Finally, among records where the MRD was other than AMI, 6.8% (38 of 563; 95% CI 4.8 to 9.2) met checklist criteria for AMI during admission, but 94.7% had an ICD-9410 code as a secondary diagnosis. CONCLUSION: A simple checklist can be very easily applied, has extremely high sensitivity for confirming the presence of AMI, and identifies a clinically significant proportion of charts with false positive codes for AMI. Conversely, these findings support the high sensitivity (low false negative rates) of conventional coding practices for AMI in Canadian hospital records, be it as a primary or secondary diagnosis (eg, 95% detection rate). Usual coding, combined with the checklist for tentative ICD-9 410 diagnoses, would improve the accuracy of Canadian hospital records.

Canada↗
PubMed1996

Coronary artery bypass mortality rates in Ontario. A Canadian approach to quality assurance in cardiac surgery. Steering Committee of the Provincial Adult Cardiac Care Network of Ontario.

BACKGROUND: This study was conducted to assess the overall mortality rate and the amount of interhospital variation in risk-adjusted mortality rates after coronary artery bypass graft (CABG) surgery in Ontario, Canada. CABG outcomes data are not publicly disseminated in Ontario. METHODS AND RESULTS: Clinical risk factors and surgical outcomes were collected on 15,608 patients undergoing isolated CABG surgery between April 1, 1991, and March 31, 1994, at the nine hospitals performing adult cardiac surgery in Ontario. The data were analyzed on the basis of a fiscal year. The overall mortality rate was 3.01%, and the risk-adjusted mortality rate declined from 3.17% in 1991 to 2.93% in 1993. In 1991, one of the nine hospitals had a risk-adjusted mortality rate significantly lower than the provincial average. Otherwise, the hospitals all had risk-adjusted mortality rates within the expected range during the time period of the study. All hospitals performed > 300 CABG procedures in 1992 and 1993, and only 2 of 42 cardiac surgeons performed < 50 CABG procedures in 1993. CONCLUSIONS: The in-hospital mortality rate after CABG surgery in Ontario is low, and the amount of interhospital variation in risk-adjusted mortality rates is no greater than that expected by chance alone. These outcomes are probably attributable to regionalization of CABG surgery and a very low prevalence of low-volume cardiac surgeons in Ontario.

Aged↗