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Biomedical subjects

C D Naylor

Publications and source records attributed to C D Naylor.

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

Are the marginal returns of coronary artery surgery smaller in high-rate areas? The Steering Committee of the Provincial Adult Cardiac Care Network of Ontario.

BACKGROUND: Population-based rates of surgery vary within and between health-care systems, causing concern that case selection is less appropriate in high-rate areas. This inverse relationship has not been shown with appropriateness criteria generated by expert panels. We applied a trials-based measure of the potential survival benefit of coronary artery bypass graft surgery (CABG) to patients in a provincial registry, to determine the relationship between survival gains and rates of CABG. METHODS: We did a population-based retrospective review of linked registry and administrative datasets. 5058 patients in the linked datasets underwent isolated CABG in Ontario between April 1, 1992, and March 31, 1993. Potential survival benefit of surgery was scored with an algorithm derived from a published overview of trials comparing CABG to medical treatment, analysed by county and by referral regions. FINDINGS: Overall, case selection was appropriate whether assessed clinically (96.3% had either severe disease as judged on the coronary arteries affected or moderate to severe angina) or on the basis of survival benefit scores (94.0% predicted to obtain moderate or high benefit). There was significant variation in benefit scores across referral regions (p < 0.001). Benefit scores correlated inversely with county surgical rate (r = -0.49, p < 0.005) and the proportion of low-benefit cases increased with rates (r = 0.50, p < 0.005). Referral regions served by high-rate surgical centres had lower mean benefit scores. INTERPRETATION: Most patients undergoing CABG in Ontario are in the high-survival benefit category. Surgery is defensible for patients with low survival benefit on the grounds of symptom relief, but the proportion of cases with low benefit rises with higher local rates of surgery. The inverse relationship between surgery rates and appropriateness of case selection may be better understood as diminishing marginal returns for specific outcomes with rising local use of procedures.

Aged↗
PubMed1996

Appropriateness of primary total hip and knee replacements in regions of Ontario with high and low utilization rates.

OBJECTIVE: To compare the appropriateness of case selection for primary hip and knee replacements between two regions in Ontario: one with a high population-based utilization rate and one with a low rate. DESIGN: Random audit of medical records sampled from hospital discharge abstracts, with subsequent implicit and explicit criteria-based assessments of the appropriateness of surgery. STUDY POPULATION: People aged 60 years or over who underwent elective, single-joint, non-fracture-related, primary hip or knee replacement between Apr. 1, 1992, and Mar. 31, 1993, at one of seven hospitals in a high-rate region (comprising Brant, Huron and Oxford countries) or one of eight hospitals in a low-rate region (comprising the cities of Scarborough and Toronto). INTERVENTIONS: Structured review of hospital medical records, with additional review of information from surgeons and family physicians' office charts if necessary. Three physicians reviewed patient data and rated the preoperative pain level and functional status of patients, with agreement among at least two reviewers. The proportion of inappropriate cases was then assessed according to explicit criteria defined by a multidisciplinary panel using the delphi process. Profiles of each case were also subjected to independent implicit review by two rheumatologists and two orthopedic surgeons. OUTCOME MEASURES: Proportion of joint replacements deemed inappropriate in the high- and low-rate regions according to either the explicit criteria or the implicit review, as well as preoperative pain levels and functional status of patients in the high- and low-rate regions. RESULTS: Hip replacements were more common among patients sampled in the low-rate region than among those in the high-rate region (57.3% v. 39.3%; p < 0.002), although the patients' baseline characteristics, including severity of preoperative pain and dysfunction, were otherwise similar between the regions. Inappropriate surgery, determined by explicit criteria, was equally uncommon in the two regions (6.4% and 6.1%). On implicit review, the two rheumatologists rated fewer cases as appropriate than did the two orthopedic surgeons (63.0% v. 80.0%; p < 0.001); however, the proportion of cases rated as inappropriate by the subspecialists was similar in the high- and low-rate regions (11.4% and 11.0%, respectively, by the rheumatologists, and 6.3% and 10.4%, respectively, by the orthopedic surgeons). CONCLUSIONS: Patients selected for primary hip or knee replacement are similar in the high- and low-rate regions of Ontario. Inappropriate use of this procedure does not account for the high rate of surgery in some areas. Further studies will be required to determine which other factors account for the regional variations in the utilization rates and whether there is underservicing in low-rate areas.

Chi-Square Distribution↗
PubMed1996

Cesarean delivery in relation to birth weight and gestational glucose tolerance: pathophysiology or practice style? Toronto Trihospital Gestational Diabetes Investigators.

OBJECTIVES: To examine the relationship between birth weight and mode of delivery among women with untreated borderline gestational diabetes mellitus (GDM), treated overt GDM, and normoglycemia. DESIGN: Prospective cohort study. SETTING: Three Toronto, Ontario teaching hospitals. PATIENTS: A total of 3778 volunteers aged 24 years or older. INTERVENTIONS: Subjects underwent a 3-hour long, 100-g oral glucose tolerance test at 28 weeks' gestation, regardless of screening test results. Usual care was provided to 143 women who met the National Diabetes Data Group criteria for GDM. Physicians were blinded to glucose tolerance test results for all others, including 115 untreated women with borderline GDM by the broader criteria of Carpenter and Coustan. MAIN OUTCOME MEASURES: Crude and adjusted rates of cesarean delivery and neonatal macrosomia (birth weight >4000 g). RESULTS: Compared with normoglycemic controls, the untreated borderline GDM group had increased rates of macrosomia (28.7% vs 13.7%, P<.001) and cesarean delivery (29.6% vs 20.2%, P=.02). Cesarean delivery in this subgroup was associated with macrosomia (45.5% vs 23.5%, P=.03). Usual care of known GDM normalized birth weights, but the cesarean delivery rate was about 33% whether macrosomia was present or absent. A clearly increased risk of cesarean delivery among treated patients compared with normoglycemic controls persisted after adjustment for multiple maternal risk factors (adjusted odds ratio, 2.1; 95% confidence interval, 1.3 to 3.6). CONCLUSIONS: Infant macrosomia was a mediating factor in high cesarean delivery rates for women with untreated borderline GDM. While detection and treatment of GDM normalized birth weights, rates of cesarean delivery remained inexplicably high. Recognition of GDM may lead to a lower threshold for surgical delivery that mitigates the potential benefits of treatment.

Adult↗
PubMed1996

Integrated delivery systems: has their time come in Canada?

In the 1990s every Canadian province is struggling to reduce health care expenditures without jeopardizing access to health care or quality of care. The authors propose a new model for health care delivery: the Canadian Integrated Delivery System (CIDS). A CIDS is a network of health care organizations; it would provide, or arrange to provide, a coordinated continuum of services to a defined population and would be held clinically and fiscally accountable for the outcomes in and health status of that population. A CIDS would serve 100,000 to 2 million people; the care it would provide would be funded on a capitation basis. For providers, there would be explicit financial incentives to minimize costs. At the same time, service quality and consumer choice of primary care practitioner would be maintained. Primary care physicians and specialists would work with other health care service providers to offer a full spectrum of care. CIDS providers would form strategic alliances with community agencies, hospitals, the private sector and other health care services not managed by the CIDS, as needed. For physicians, affiliation with a CIDS that provided strong clinical leadership could be beneficial to their income stability and autonomy. Pilot projects of this model in several communities would determine whether this concept is feasible in the Canadian health care context.

Canada↗
PubMed1996

Triiodothyronine augmentation in the treatment of refractory depression. A meta-analysis.

BACKGROUND: Several trials have addressed the efficacy of liothyronine sodium therapy in euthyroid, nonpsychotic depressed patients refractory to tricyclic antidepressant therapy. We undertook a meta-analysis of these trials. METHODS: The MEDLINE database (1966 to May 1995) and published reference lists were examined for controlled clinical trials of triiodothyronine augmentation in euthyroid patients with refractory depression. Quality assessment and data abstraction were performed independently by two reviewers. Results were aggregated three ways: the relative response rate compared with controls, accepting each trial's definition of clinical response; absolute improvement in response rates; and improvements in depression scores, analyzed as continuous variables without a prespecified threshold for clinical response. RESULTS: Aggregating eight studies with a total of 292 patients, patients treated with triiodothyronine augmentation were twice as likely to respond as controls (relative response, 2.09; 95% confidence interval [CI], 1.31 to 3.32; P = .002). This corresponded to a 23.2% absolute improvement in response rates (95% CI, 4.5% to 41.9%; P = .02). Improvements in depression scores were moderately large (standardized effect size, 0.62; P < .001). However, study quality was uneven, and results were statistically heterogeneous. Among the four randomized double-blind studies, pooled effects were not significant (relative response, 1.53; 95% CI, 0.70 to 3.35; P = .29), but one study with negative results accounted for most of the intertrial heterogeneity in results. CONCLUSIONS: Triiodothyronine augmentation may be an effective empirical method of increasing response rates and decreasing depression severity scores in a subgroup of patients with depression refractory to tricyclic antidepressant therapy, but the total number of patients randomized was small, and additional placebo-controlled data are required for a definitive verdict. Since therapeutic trends now favor other drugs, future trials might usefully examine triiodothyronine augmentation with selective serotonin reuptake inhibitors or compare potentiation strategies, eg, lithium vs triiodothyronine, for managing refractory depression. Such trials would benefit from much larger sample sizes than those reviewed here.

Adult↗
PubMed1996

Cardiopulmonary bypass, rewarming, and central nervous system dysfunction.

BACKGROUND: During cardiopulmonary bypass a nasopharyngeal temperature greater than 38 degrees C at the end of rewarming may indicate cerebral hyperthermia. This could exacerbate an ischemic brain injury incurred during cardiopulmonary bypass. METHODS: In a cohort of 150 aortocoronary bypass patients neuropsychologic test scores of 66 patients whose rewarming temperature exceeded 38 degrees C were compared with those who did not. There were no differences between groups with respect to demographic and intraoperative variables. RESULTS: A trend was seen for hyperthermic patients to do worse on all neuropsychologic tests in the early postoperative period but not at 3-month follow-up. By analysis of covariance hyperthermic patients did worse on the visual reproduction subtest of the Weschler memory scale at 3 months (p = 0.02), but this difference was not found by linear regression (p = 0.10). CONCLUSIONS: We were unable to demonstrate any significant deterioration in patients rewarmed to greater than 38 degrees C in the early postoperative period. The poorer performance in the visual reproduction subtest of the Wechsler memory scale at 3 months in the group rewarmed to more than 38 degrees C is interesting but far from conclusive. Caution with rewarming is still advised pending more in-depth study of this issue.

Body Temperature↗
PubMed1996

Characteristics and mortality outcomes of thrombolysis trial participants and nonparticipants: a population-based comparison.

OBJECTIVES: This study was done to compare characteristics and outcomes of patients with acute myocardial infarction participating in two thrombolysis trials with those of nontrial patients at study hospitals and external hospitals. BACKGROUND: Preferential recruitment of lower risk patients into randomized trials of thrombolysis has been suggested by earlier studies. However, to date there has not been a definitive population-based comparison of characteristics and outcomes for thrombolysis trial participants and nonparticipants. METHODS: Population-based data on hospital admissions and mortality from acute myocardial infarction for all hospitals in Ontario from 1989 to 1992 were linked to data on trial participants in two distinct thrombolysis studies (GUSTO I and LATE). Included were 1,304 patients entered into GUSTO, 12,657 nonparticipants at GUSTO hospitals, 249 patients entered into LATE, 5,997 nonparticipants at LATE hospitals and 12,299 patients at external hospitals. The main outcomes were differences in age, gender, comorbidity scores, coronary revascularization and survival to hospital discharge. RESULTS: Patients in both GUSTO and LATE were significantly more likely to be <70 years old (odds ratio [OR] 2.8 and 3.2, respectively), to be male (OR 2.0 and 2.1, respectively), to have low comorbidity scores (OR 2.0 and 2.3, respectively) and, for GUSTO alone, to undergo coronary revascularization (OR 2.4). Nontrial patients were similar between trial hospitals and external hospitals. In-hospital mortality rates for GUSTO and LATE patients were lower (6.9% and 6.6%, respectively) than for nonparticipants at study hospitals (16.8% and 19.7%, respectively; p<0.001 for both comparisons). Survival to hospital discharge remained higher among GUSTO (OR 1.9) and LATE patients (OR 2.0) than nonparticipants at study hospitals even after adjustment for age, gender, revascularization and comorbidity scores. CONCLUSIONS: Compared with nontrial patients, thrombolysis trial participants are younger, more often male, undergo more revascularization and have less comorbid disease. Even after adjustment for these factors, participants have a survival advantage over nonparticipants that is larger than expected from thrombolysis alone. These findings are not attributable to inferior care or skewed populations at hospitals that did not join these major trials. Further study of these selection biases may guide future trial design and deepen our understanding of why thrombolytics have been underused for high risk patients in routine practice.

Age Factors↗
PubMed1996

Impact of preoperative risk and perioperative morbidity on ICU stay following coronary bypass surgery.

Prolonged intensive care unit treatment (> 3 days) contributes to increased health costs and resource utilization. In order to devise strategies to limit intensive care unit stay, and provide cost-effective medical care, it is necessary to identify the pre- and perioperative risk factors of prolonged treatment. Over 100 potential risk variables were collected prospectively in 889 consecutive patients undergoing isolated coronary bypass surgery between 1990 and 1992. The incidence of intensive care unit therapy lasting > 3 days was 6.8%. Univariate statistics identified 23 pre- and perioperative variables that were potential contributors to prolonged intensive care unit therapy. However, multivariate analysis of preoperative risk variables identified only recent myocardial infarction (within 30 days of surgery) and continued preoperative smoking (within 30 days of surgery) to be independent risk factors. Only 6.3% of patients without preoperative myocardial infarction and 6.1% of non-smokers required prolonged intensive care unit treatment, compared with 14.8% of patients with preoperative myocardial infarction (P = 0.01) and 10.1% of smokers (P = 0.07). When multivariate analysis was repeated with both pre- and perioperative variables, only ischemic morbidity (inotropes, myocardial infarction and low-output syndrome; 138 patients) and non-ischemic morbidity (infection, stroke or bleeding; 37 patients) predicted prolonged intensive care unit treatment. Intensive care unit treatment for > 3 days occurred in 26.8% of patients with ischemic morbidity compared with 3.2% of patients without ischemic morbidity (P = 0.001). Prolonged intensive care stay occurred in 32.4% of patients who suffered non-ischemic complications compared with 5.7% of patients who did not suffer these complications. The multiple logistic regression analysis odds ratio for ischemic morbidity was 7.4 (95% c.i. 4.0-13.4) compared with 4.8 (95% c.i. 1.9-10.1) for non-ischemic morbidity. Strategies designed to reduce the incidence of prolonged intensive care unit treatment should include prevention of stroke, infection and bleeding. However, the greatest reduction of intensive care unit utilization would be mediated by prevention of ventricular dysfunction secondary to myocardial ischemia or inadequate myocardial preservation.

Adult↗
PubMed1996

Hospital volume, calendar age, and short term outcomes in patients undergoing repair of abdominal aortic aneurysms: the Ontario experience, 1988-92.

OBJECTIVE: To determine, for abdominal aortic aneurysm surgery, whether a previously reported relationship between hospital case volume and mortality rate was observed in Ontario hospitals and to assess the potential impact of age on the mortality rate for elective surgery. DESIGN: Population based observational study using administrative data. SETTING: All Ontario hospitals where repair of abdominal aortic aneurysm as a primary procedure was performed during 1988-92. PATIENTS: These comprised 5492 patients with unruptured abdominal aortic aneurysms and 1203 patients with ruptured abdominal aortic aneurysms admitted to hospital between 1988-92 for repair of abdominal aortic aneurysm as a primary procedure. MAIN OUTCOMES: In-hospital death and length of in-hospital stay. RESULTS: The case fatality rate was 3.8% for unruptured abdominal aortic aneurysms and 40.0% for ruptured abdominal aortic aneurysms. For unruptured cases, after adjustment for patient and hospital covariates, each 10 case per year increase in hospital volume was related to a 6% reduction in relative odds of death (odds ratio (OR) 0.94, 95% confidence intervals 0.88, 0.99) and 0.29 days reduction (95% CI -0.22, -0.35) in postoperative in-hospital stay. Female sex (OR 1.53, 95% CI 1.08, 2.18) and transfer from another acute care hospital (OR 4.37, 95% CI 2.62, 7.29) were associated with increased case fatality rates among patients in the unruptured category. For ruptured cases, neither the case fatality rate nor postoperative in-hospital stay were significantly related to hospital volume. The case fatality rates increased linearly and substantially with advancing age both for unruptured and ruptured aneurysms, and the excess risk of postoperative death in ruptured as compared to unruptured aneurysms was substantially higher in older patients. CONCLUSION: The relationship between hospital volume and mortality or morbidity was very modest and observed only for elective surgery. Case fatality rates in patients with ruptured abdominal aortic aneurysms remained 10 times higher than for patients with unruptured abdominal aortic aneurysms, despite improvements in overall mortality in comparison to previously published data. More effective detection of aneurysms, including elective repair for those once considered "high risk" older patients, might further reduce the toll from ruptured aortic aneurysms.

Age Factors↗
PubMed1996

Primary hip and knee replacement surgery: Ontario criteria for case selection and surgical priority.

OBJECTIVES: To develop, from simple clinical factors, criteria to identify appropriate patients for referral to a surgeon for consideration for arthroplasty, and to rank them in the queue once surgery is agreed. DESIGN: Delphi process, with a panel including orthopaedic surgeons, rheumatologists, general practitioners, epidemiologists, and physiotherapists, who rated 120 case scenarios for appropriateness and 42 for waiting list priority. Scenarios incorporated combinations of relevant clinical factors. It was assumed that queues should be organised not simply by chronology but by clinical and social impact of delayed surgery. The panel focused on information obtained from clinical histories, to ensure the utility of the guidelines in practice. Relevant high quality research evidence was limited. SETTING: Ontario, Canada. MAIN MEASURES: Appropriateness ratings on a 7-point scale, and urgency rankings on a 4-point scale keyed to specific waiting times. RESULTS: Despite incomplete evidence panellists agreed on ratings in 92.5% of appropriateness and 73.8% of urgency scenarios versus 15% and 18% agreement expected by chance, respectively. Statistically validated algorithms in decision tree form, which should permit rapid estimation of urgency or appropriateness in practice, were compiled by recursive partitioning. Rating patterns and algorithms were also used to make brief written guidelines on how clinical factors affect appropriateness and urgency of surgery. A summary score was provided for each case scenario; scenarios could then be matched to chart audit results, with scoring for quality management. CONCLUSIONS: These algorithms and criteria can be used by managers or practitioners to assess appropriateness of referral for hip or knee replacement and relative rankings of patients in the queue for surgery.

Algorithms↗
PubMed1996

Cholesterol policy and the primary prevention of coronary disease: reflections on clinical and population strategies.

Despite billions of dollars spent on targeted and population-wide strategies aimed at reducing human consumption of saturated fat and cholesterol, aspects of the diet-heart connection remain a source of debate. At least part of the uncertainty arises from a growing appreciation that the relationship between dietary habits, serum lipids, and atherosclerosis is more complex than was previously thought. While we wait for answers from clinical and basic research, what is to be done? This review examines evidence about clinical policies and population strategies for the primary prevention of coronary disease, with specific reference to diet and dyslipidemias. It also summarizes some current policies and offers conclusions about broad directions for further policy development.

Attitude to Health↗
PubMed1996

Trends and variations in the use of vascular surgery in Ontario.

OBJECTIVE: To measure changes over time in overall surgical rates and geographic rate variations for three major vascular procedures (abdominal aortic aneurysm repairs, peripheral vascular disease procedures and carotid endarterectomies). BACKGROUND: There is little research literature on population-based usage profiles of vascular procedures. The three procedures profiled were all subject to marked shifts in evidence or surgical opinions, raising the issue of the interplay between temporal trends and geographic variations in their use. METHODS: Based on Ontario's hospital discharge abstracts and census data, population-based usage rates were calculated by site of patient residence from 1981 to 1991. Extent of rate variation was summarized with the coefficient of variation, systematic component of variation and the adjusted-likelihood ratio chi2. Spearman rank correlations were also calculated to assess stability of county rankings for each procedure. RESULTS: The overall rates of peripheral vascular procedures and repair for abdominal aortic aneurysms fell 24% and increased 42% respectively. The overall rate of carotid endarterectomies dropped from 46/100,000 in 1981 to 20/100,000 in 1989, but by 1991 had increased to 37/100,000. Through the decade measures of variation fell minimally for all three procedures. CONCLUSION: Overall use of vascular procedures shifted in apparent response to new research evidence and technologies. Despite marked changes in surgical rates, the extent of geographic variation was stable, suggesting that differing factors influence overall surgical rates and geographic rate variations. Audit at the local level using primary clinical data is needed to understand why disparities in use persist.

Aortic Aneurysm, Abdominal↗
PubMed1995

Waiting for coronary artery bypass surgery: population-based study of 8517 consecutive patients in Ontario, Canada. The Steering Committee of the Adult Cardiac Care Network of Ontario.

Deaths and delays in queues for coronary surgery in Canada have been highlighted by American interest groups opposed to "socialized medicine". Since 1991 all nine cardiac surgery centres in Ontario register and follow patients after acceptance for surgery. We examined the experience of 8517 consecutive patients leaving the registry from October 1991 to July 1993. Individual acuity scores were determined based on symptoms, angiographic findings, left ventricular function, and, where available, non-invasive tests of ischaemic jeopardy. Planned surgery was declined or deferred for 3.2% of registrants. While in the queue, 31 (0.4%) patients died and three had surgery indefinitely deferred after a non-fatal myocardial infarction. Among 8213 patients receiving surgery, the median wait was 17 days (inter-quartile range [IQR]: 4, 51), ranging from one day (IQR 0:4) for patients needing very urgent surgery (acuity score 2-3) to 42 days (IQR: 18, 77) for those rated low priority (acuity score 6-7). In a multivariate analysis, the most important determinant of waiting time was symptom status (p < 0.001), followed by anatomy (p < 0.001). Age did not alter waiting time; depending on statistical methods, female sex was either not significant or independently associated with approximately 11% relative delay (p = 0.001). Whether controlling for significant clinical factors or the multifactorial acuity scores, waiting times clearly varied (p < 0.001) among hospitals. We conclude that, during 1991-93, patients queuing for coronary surgery in Ontario rarely suffered critical events or extreme delays, and individual variation in waiting times primarily reflected clinical acuity. Nonetheless, symptoms provoked by very modest exertion were commonplace in the queue, and waiting times did vary inequitably among hospitals.

Aged↗
PubMed1995

Pitfalls in nonrandomized outcomes studies. The case of incidental appendectomy with open cholecystectomy.

OBJECTIVES: To assess the short-term outcomes of incidental appendectomy through analysis of hospital administrative data and determine the consistency and plausibility of the observed results. DESIGN: Population-based historical cohort study. SETTING: All general hospitals in Ontario between 1981 and 1990. PATIENTS: Patients undergoing open primary cholecystectomy with (7846 exposed) and without (191,599 unexposed) incidental appendectomy. MAIN OUTCOME MEASURES: In-hospital fatality rates, complication rates, and lengths of hospital stay. RESULTS: Crude comparisons showed a striking and paradoxical reduction in mortality after cholecystectomy when incidental appendectomy was performed (odds ratio [OR], 0.37; 95% confidence interval [CI], 0.23 to 0.57; P < .001); mean length of stay was also lower by -0.46 day (P < .001). After adjustment for confounding differences, such as comorbidity and nonelective surgery, mortality and lengths of stay were similar for exposed and unexposed patients; but exposed patients showed a significant increase in nonfatal complications (OR, 1.53; 95% CI, 1.39 to 1.68; P < .001). Adverse effects from incidental appendectomy emerged consistently for all three outcomes only after restricting the analysis to subgroups of patients at low surgical risk. The increased mortality for exposed patients was largest among low-risk groups; for example, among those younger than 70 years undergoing elective surgery, the OR was 2.65 (95% CI, 1.25 to 5.64; P < .001). CONCLUSION: These findings suggest that incidental appendectomy is associated with a small but definite increase in adverse postoperative outcomes. However, plausible and consistent findings were only obtained after restricting the analysis to low-risk subgroups in which unmeasured differences in patients' baseline characteristics were less likely to confound adjusted outcome comparisons. This exercise highlights the potential pitfalls in nonrandomized outcomes comparisons using data sources with limited clinical detail, such as hospital discharge abstracts.

Adult↗