Daryl S. Kucey

Risk Factors for Death or Stroke After Carotid Endarterectomy. Observations From the Ontario Carotid Endarterectomy Registry

Background and Purpose— Carotid endarterectomy is an effective method for preventing strokes if patients do not suffer adverse perioperative outcomes. The purpose of this study was to identify preoperative patient risk factors for adverse outcomes (death or nonfatal stroke) after carotid endarterectomy through the use of a large population-based registry from Ontario, Canada. Methods— Medical records of all 6038 patients who underwent carotid endarterectomy in Ontario between January 1, 1994, and December 31, 1997, were abstracted from 34 hospitals. Patient characteristics (demographic data, past medical history, neurological symptoms, comorbidities, radiological findings) and 30-day postoperative death or stroke rates were analyzed with logistic regression analysis. Results— The overall 30-day death or stroke rate after surgery was 6.0%. A history of transient ischemic attack or stroke (odds ratio [OR], 1.75; 95% confidence interval [CI], 1.39 to 2.20), atrial fibrillation (OR, 1.89; 95% CI, 1.29 to 2.76), contralateral carotid occlusion (OR, 1.72; 95% C.I., 1.25 to 2.38), congestive heart failure (OR, 1.80; 95% CI, 1.15 to 2.81), and diabetes (OR, 1.28; 95% CI, 1.01 to 1.63) were significant independent predictors for 30-day death or stroke. These 5 factors were combined into a simple risk score that can be used to stratify patients into different risk groups for complications after surgery. Conclusions— Several patient characteristics predict the development of stroke and death after carotid endarterectomy. These characteristics may help clinicians in patient counseling and contribute to studies “benchmarking” the outcomes of carotid surgery in the community setting.

Determinants of outcome after carotid endarterectomy

BACKGROUND The efficacy of carotid endarterectomy for selected patients has been evaluated with randomized controlled clinical trials. The generalizability of these studies to average surgical practice remains an important public health concern. OBJECTIVE The objective of the study was to determine the predictors of outcome after carotid endarterectomy on a regional basis. PATIENTS AND METHODS The study was designed as a retrospective cohort study and included all consecutive patients presented for carotid endarterectomy at the 8 University of Toronto-affiliated hospitals in the period from January 1, 1994, to December 31, 1996. The main outcome measure was 30-day postoperative stroke or death rate. RESULTS During the study interval, 1280 primary carotid endarterectomies were performed. The overall combined stroke and death rate was 6.3% for all patients who underwent endarterectomy (4.0% for patients who were asymptomatic). The significant predictors of poor outcome were the following: presenting symptoms (odds ratio, 1.74; 95% confidence interval [CI], 0.96, 3.12), low surgeon volume (<6 cases per year; odds ratio, 3.98; 95% CI, 1.65, 9.58), and left-sided surgery (odds ratio, 1.72; 95% CI, 1.07, 2.76). CONCLUSION These data suggest that adoption of the recommendations of the symptomatic carotid endarterectomy trials is appropriate. However, endarterectomy for asymptomatic lesions remains of uncertain benefit on a regional basis and must be individualized to the experience of the specific surgeon. The surgeon volume/outcome relationship that is identified in this study suggests a need for a minimum volume threshold for this procedure.

Sex Differences in Carotid Endarterectomy Outcomes Results From the Ontario Carotid Endarterectomy Registry

Background and Purpose— The existing literature provides conflicting evidence on surgical risks of carotid endarterectomy in women compared with men. We used data from a large population-based carotid surgery registry to determine whether sex differences exist in the risk of perioperative complications from carotid endarterectomy. Methods— We analyzed data from the Ontario Carotid Endarterectomy Registry, which contains data on all patients who underwent carotid endarterectomy in the province of Ontario between 1994 and 1997. We compared the risk of death or stroke at 30 days in women and men and used multivariate analyses to adjust for age, comorbid conditions, and surgical factors. Secondary analyses compared the risks of death and/or stroke in women and men at 2 years after surgery. Results— The study sample consisted of 6038 patients (35% women). The risks of perioperative stroke or death were not significantly different in women compared with men (adjusted hazard ratio, 1.10; 95% CI, 0.90 to 1.35). The combined risk of stroke or death at 2 years after surgery was also similar in women and men (adjusted hazard ratio, 1.05; 95% CI, 0.92 to 1.21). However, women were more likely to have a stroke (adjusted hazard ratio, 1.26; 95% CI, 1.05 to 1.51) and less likely to die (adjusted hazard ratio, 0.82; 95% CI, 0.68 to 0.99) within 2 years after surgery. Conclusions— Perioperative complication rates from carotid endarterectomy are similar in women and men. Women should not be discouraged from carotid endarterectomy solely on the basis of surgical risks.

Use of interventional procedures for peripheral arterial occlusive disease in Ontario between 1991 and 1998: a population-based study

PURPOSE Although peripheral arterial occlusive disease (PAOD) is a public health issue in the elderly population, limited population-based data are available on use of interventional procedures in Canada. We describe trends in use of interventional procedures to treat PAOD in Ontario over the past decade. METHODS A retrospective population-based cohort study was conducted for fiscal years 1991 to 1998 with Ontario administrative databases to identify all arterial bypass surgeries, angioplasty procedures, and amputations performed. RESULTS A total of 19,332 bypass operations, 16,334 angioplasty procedures, and 17,534 amputations were identified. Population-based rates showed that angioplasty use peaked at about 110 per 100,000 at age 65 to 74 years, arterial bypass surgery use peaked at 129 per 100,000 at age 75 to 84 years, and amputation use peaked at 138 per 100,000 at age 85 years or older. All types of interventional procedures to treat PAOD were performed more frequently in men than in women. Age-adjusted and sex-adjusted rate of arterial bypass surgery decreased significantly, from 77 to 61 per 100,000 population aged 45 years or older (P =.0002, linear regression analysis), whereas rate for PTA increased significantly, from 59 to 75 per 100,000 population aged 45 years or older (P =.0005). The overall major amputation rate declined slightly over the study period, influenced by the decreased rate in patients aged 85 years or older. The revascularization rate in patients aged 85 years or older increased (P =.055). CONCLUSION Reduced use of arterial bypass surgery and increased use of angioplasty procedures has occurred over the past decade and may reflect a change in the practice pattern of vascular surgeons in Ontario, who have become more conservative in treating localized disease and reserve surgical interventions for more severe forms of PAOD. The slight reduction in overall major amputation rate, driven by decreased rate in patients aged 85 years or older, may reflect a trend toward a more aggressive revascularization approach in this age group.

Outcome of revascularization procedures for peripheral arterial occlusive disease in Ontario between 1991 and 1998: a population-based study

PURPOSE We describe the outcome of revascularization procedures used to treat peripheral arterial occlusive disease (PAOD), using population-based administrative data. METHODS A retrospective population-based cohort study utilizing administrative databases in Ontario, Canada, was conducted for fiscal years 1991 to 1998 to identify patients who underwent arterial bypass surgery and percutaneous transluminal angioplasty to treat PAOD. The Kaplan-Meier method was used to calculate cumulative survival rate and amputation-free survival rate. To analyze factors that affect these rates, multivariate analysis was performed with Cox proportional hazard models. RESULTS Over the study period 15,824 patients underwent bypass operations and 11,548 underwent angioplasty. For patients who underwent bypass surgery, 5-year cumulative survival rate was 61.5% and major amputation-free survival rate was 83.4%, compared with 69% and 92.2%, respectively, for patients who underwent angioplasty. Male sex, older age, diabetes, and heart disease were associated with increased risk for death after revascularization procedures. Increased risk for major amputation after revascularization procedures was associated with male sex, older age, and diabetes, whereas hypertension was linked to decreased risk. CONCLUSION To evaluate the long-term outcome of revascularization procedures for PAOD at the population level, survival and major amputation-free survival rates should be used, because they provide more clinically accepted estimates compared with the correlation between utilization rates for revascularization and amputation procedures, which have been used to describe outcome in previously published reports in the literature.

Decision analysis for the surgeon.

Abstract. Surgical practice, by nature, is full of important decision making scenarios. Surgeons have begun to utilize the decision sciences as a methodology of approaching clinically relevant surgical problems. This article provides a brief overview of some of the important concepts of the decision sciences as they apply to practicing surgeons. Concepts discussed include the basic principles behind decision trees, valuing outcomes, and Markov modeling as well as the pros and cons of the decision analytic approach. Decision analysis is a valuable aid in determining answers to clinical scenarios, and understanding the principles behind this methodology is an important addition to the armamentarium of all practicing surgeons.

Platelet-activating factor primes endotoxin-stimulated macrophage procoagulant activity

Macrophage procoagulant activity (PCA) at the site of inflammation may be induced by several stimuli including bacteria and endotoxin (LPS). The local factors controlling PCA induction are poorly defined. The lipid mediator platelet-activating factor (PAF) is ubiquitous to inflammatory sites. To determine the effect of PAF on LPS-induced PCA, thioglycolate-elicited murine peritoneal macrophages were exposed to PAF (10(-7) M) or control medium for 30 min and then stimulated with LPS (10 micrograms/ml) for 2, 4, or 6 hr. The ability of macrophages to shorten the clotting time of plasma (ie., PCA) was then measured and clotting times were converted to PCA units using a thromboplastin standard. Cytosolic calcium ([Ca2+]i) measurements were made using the calcium-sensitive fluorescent dye indo-1. PAF alone did not induce a rise in PCA expression (medium alone, 47 +/- 11 mU/10(6) cells; PAF alone, 49 +/- 12 mU/10(6) cells at t = 4 hr), but PAF treatment prior to LPS exposure resulted in a significant increase in the LPS-stimulated expression of PCA (LPS alone, 190 +/- 29 mU/10(6) cells; PAF/LPS, 329 +/- 57 mU/10(6) cells at t = 4 hr, P less than 0.05). This priming effect was reversed by the PAF antagonist WEB 2086 (WEB/PAF/LPS, 196 +/- 31 mU/2 x 10(6) cells). Stimulation of cells with PAF alone resulted in a rapid rise in [Ca2+]i (resting, 213 +/- 19 nmole; peak, 577 +/- 35 nmole). This effect was also inhibited by WEB 2086. These data suggest that PAF plays an important role in the modulation of PCA production by macrophages.(ABSTRACT TRUNCATED AT 250 WORDS)

v) The Management of Vascular Injuries in Extremity Trauma

Abstract Unrecognised vascular injuries following extremity trauma can result in disastrous outcomes ranging from limb dysfunction to amputation. All extremity trauma should be approached with a high index of suspicion for vascular injuries. Clinical examination is the mainstay of diagnosis. The role of Colour Flow Doppler scanning is expanding. In the operating room, patients should be heparinised, damaged arterial segments should be debrided and primary end-to-end anastomosis is the preferred method of repair. Compartment syndrome and thrombosis are major postoperative complications that demand prompt diagnosis and treatment.

Modulation of macrophage procoagulant activity by arachidonic acid metabolites

Macrophage (M phi)-mediated fibrin deposition via induction of procoagulant activity (PCA) is an important component of the host response during various infections. While endotoxin (LPS) is a well-known stimulus of PCA, the factors modulating its activity within the inflammatory microenvironment are unknown. The purpose of these studies was to determine the relative roles of two pathways of arachidonic acid metabolism, i.e., the cyclooxygenase (CO) and 5-lipoxygenase (5-LO) pathways, in modulating M phi PCA induction by LPS. Thioglycolate-elicited murine peritoneal M phi were treated with the CO inhibitor indomethacin (INDO), the 5-LO inhibitor nordihydroguaiaretic acid (NDGA), or control vehicle for 15 min prior to a 4-hr exposure to LPS (10 micrograms/ml). The ability of M phi to shorten the clotting time of plasma (i.e., PCA) was measured and clotting times were converted to PCA units via a thromboplastin standard. While CO blockade had no effect on PCA induction by LPS (without INDO 30 microM 446 +/- 131, with INDO 30 microM 546 +/- 193, mU/2 x 10(6) cells, n = 4), NDGA caused a dose-dependent inhibition (IC50 = 3 microM) without affecting cell viability (without NDGA 3 microM 446 +/- 131, with NDGA 3 microM 191 +/- 67, mU/2 x 10(6) cells, n = 6, P less than 0.05). Induction of PCA by Escherichia coli was similarly inhibited (E. coli 10(6) alone = 518 +/- 130; with NDGA 3 microM = 234 +/- 100, n = 2). Combined NDGA/INDO reduced PCA comparable to NDGA alone, ruling out the possibility that NDGA acted through generation of inhibitory prostanoids like PGE2.(ABSTRACT TRUNCATED AT 250 WORDS)