Diagnostic-therapeutic cascade revisited: coronary angiography, coronary artery bypass graft surgery, and percutaneous coronary intervention in the modern era.

BACKGROUND: There is wide geographic variation in the use of coronary revascularization in the United States. Rates are closely related to rates of coronary angiography. We assessed the relationship between coronary angiography and coronary artery revascularization by procedure type (coronary artery bypass graft surgery or percutaneous coronary intervention). METHODS AND RESULTS: Using Part B claims for a 20% sample of the Medicare population, we calculated population-based rates of testing and treatment by region, using events identified in Part B claims as the numerator and the total number of Medicare beneficiaries residing in the area as the denominator and adjusting for regional differences in demographic characteristics with the indirect method. Cardiac catheterization rates varied substantially across regions, from 16 to 77 per 1000 Medicare beneficiaries. The relationship between coronary angiography rates and total coronary revascularization rates was strong (R(2)=0.84). However, there was only a modest association between coronary angiography rates and coronary artery bypass graft surgery rates (R(2)=0.41) with the suggestion of a threshold effect. The association between coronary angiography rates and percutaneous coronary intervention rates was strong (R(2)=0.78) and linear. CONCLUSIONS: The diagnostic-therapeutic cascade for coronary artery disease differs by therapeutic intervention. For coronary artery bypass graft surgery, the relationship is modest, and there appears to be a testing threshold beyond which additional tests do not result in additional surgeries. For percutaneous coronary intervention, the relationship is very tight, and no threshold appears to exist. Given the results of recent studies of medical versus invasive management of stable coronary disease, patients living in high-diagnostic-intensity regions may be getting more treatment than they want or need.

Cardiologists performing peripheral angioplasties: impact on utilization.

CONTEXT: Angioplasty and stent placement for peripheral arterial occlusive disease has traditionally been performed by radiologists and surgeons. However, cardiologists have recently begun to perform these procedures. It is unknown whether this has affected how often the procedure is done. OBJECTIVE: To assess how the proportion of peripheral angioplastics performed by cardiologists in a geographic area relates to population-based angioplasty rates. DESIGN: Cross-sectional analysis of all U.S. Medicare beneficiaries undergoing peripheral arterial (i.e., renal, iliac, or lower extremity) angioplasty in 1996 using Part B (physician) claims for cardiovascular procedures. Physician specialty was obtained from the American Medical Association's masterfile and Medicare. MEASURES: For each of the 306 U.S. hospital referral regions (HRRs), we calculated the proportion of procedures performed by cardiologists and rates of peripheral arterial angioplasty (adjusted for age, sex, and race). RESULTS: More than 37,000 peripheral arterial angioplastics were performed on Medicare beneficiaries in 1996 (50% for lower extremity, 33% iliac, and 17% renal arterial disease). Cardiologists performed 26% of these procedures overall, including 37% of the renal angioplastics. Few (12%) procedures were done as part of a cardiac catheterization; instead, most were done as a separate procedure. Use of peripheral angioplasty varied more than 14-fold across HRRs (median, 12 procedures per 10,000 beneficiaries; 10th to 90th percentile, 4.1 to 57.9). The mean angioplasty rate in HRRs where cardiologists performed 50% or more of the procedures was almost double that of regions where they performed none (21.9 vs. 12.1 procedures per 10,000 beneficiaries; P < 0.001). CONCLUSIONS: Cardiologists are performing a substantial proportion of peripheral angioplasties. Rates of these procedures are highest in regions where cardiologists do most of the angioplasties.

Survival of patients with diabetes and multivessel coronary artery disease after surgical or percutaneous coronary revascularization: results of a large regional prospective study. Northern New England Cardiovascular Disease Study Group.

OBJECTIVES: We sought to assess survival among patients with diabetes and multivessel coronary artery disease (MVD) after percutaneous coronary intervention (PCI) and after coronary artery bypass grafting surgery (CABG). BACKGROUND: The Bypass Angioplasty Revascularization Investigation (BARI) demonstrated that diabetics with MVD survive longer after initial CABG than after initial PCI. Other randomized trials or observational databases have not conclusively reproduced this result. METHODS: A large, regional database was linked to the National Death Index to assess five-year mortality. Of 7,159 consecutive patients with diabetes who underwent coronary revascularization in northern New England during 1992 to 1996, 2,766 (38.6%) were similar to those randomized in the BARI trial. Percutaneous coronary intervention was the initial revascularization strategy in 736 patients and CABG in 2,030. Cox proportional hazards regression was used to calculate risk-adjusted hazard ratios (HR) and 95% confidence intervals (CI 95%). RESULTS: Patients who underwent PCI were younger, had higher ejection fractions and less extensive coronary disease. After adjusting for differences in baseline clinical characteristics, patients with diabetes treated with PCI had significantly greater mortality relative to those undergoing CABG (HR = 1.49; CI 95%: 1.02 to 2.17; p = 0.037). Mortality risk tended to increase more among 1,251 patients with 3VD (HR = 2.02; CI 95%: 1.04 to 3.91; p = 0.038) than among 1,515 patients with 2VD (HR = 1.33; CI 95%: 0.84 to 2.1; p = 0.21). CONCLUSIONS: In this analysis of a large regional contemporary database of patients with diabetes selected to be similar to those enrolled in the BARI trial, five-year mortality was significantly increased after initial PCI. This supports the BARI conclusion on initial revascularization of patients with diabetes and MVD.

Safety and efficacy of percutaneous coronary interventions performed immediately after diagnostic catheterization in northern new england and comparison with similar procedures performed later.

"Ad hoc" percutaneous coronary interventions (PCIs)-those performed immediately after diagnostic catheterization-have been reported in earlier studies to be safe with a suggestion of higher risk in certain subgroups. Despite increasing use of this strategy, no data are available in recent years with new device technology. We studied use of an ad hoc strategy in a large regional population to determine its use and outcomes compared with staged procedures. A database from the 6 centers performing PCIs in northern New England and 1 center in Massachusetts was analyzed. During 1997, excluding only patients requiring emergency procedures or those with a prior PCI, 4,136 PCIs were performed, 1,748 (42.3%) of these being ad hoc procedures. Patients having ad hoc procedures were less likely to have peripheral vascular disease, renal failure, prior myocardial infarction, or coronary artery bypass surgery, congestive heart failure, or poor left ventricular function, and more likely to have received preprocedural intravenous heparin or nitroglycerin or to have required an urgent procedure. Narrowings treated during ad hoc procedures were less frequently types B and C or in saphenous vein grafts. Adjusted rates of clinical success were not different between ad hoc and non-ad hoc procedures (93.7% vs 93.6%); there was no difference in the incidence of death (0.6% vs 0.5%), emergency (0. 9% vs 0.8%) or any (1.4% vs 0.8%) coronary artery bypass surgery, or myocardial infarction (2.6% vs 2.0%). As currently practiced in our region, ad hoc intervention is used selectively with outcomes similar for ad hoc and non-ad hoc procedures.

Variation in the use of laparoscopic cholecystectomy for elderly patients with acute cholecystitis.

HYPOTHESIS: There is regional variation in the use of laparoscopic cholecystectomy (LC) for acute cholecystitis in the New England (Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, and Connecticut) Medicare population. DESIGN: Population-based, cross-sectional study. SETTING: Hospital service areas (HSAs), small geographic areas reflecting local hospital markets, in New England. PATIENTS: We identified from the claims database 21 570 Medicare patients undergoing cholecystectomy between 1995 and 1997. Patients with acute calculous cholecystitis but no bile duct stones (n = 6156) were then identified using International Classification of Diseases, Ninth Revision diagnostic codes. To reduce variation by chance, we excluded patients residing in HSAs with fewer than 26 cases, leaving 5014 patients in 77 HSAs. MAIN OUTCOME MEASURES: For each HSA, we assessed the rate of cholecystectomies performed laparoscopically, mortality, and hospital length of stay. RESULTS: Overall, 53.5% of patients with acute cholecystitis underwent LC. There was wide regional variation in the rate of patients undergoing laparoscopic surgery, from 30.3% in the Salem, Mass, HSA to 75.5% in the Hyannis, Mass, HSA. Seventeen HSAs had rates below 40%, while 9 had rates above 70%. The average length of stay (7.6 days) was approximately 1 day shorter in HSAs with high rates of patients undergoing LC than in other HSAs. There was no correlation between regional use of laparoscopic surgery and 30-day mortality (3.1% overall). CONCLUSIONS: The likelihood of elderly patients with acute cholecystitis receiving LC depends strongly on where they live. Efforts to reduce regional variation should focus on disseminating techniques for safe LC in this high-risk population.

Relation between operator and hospital volume and outcomes following percutaneous coronary interventions in the era of the coronary stent.

CONTEXT: Studies have found an association between physician and institution procedure volume for percutaneous coronary interventions (PCIs) and patient outcomes, but whether implementation of coronary stents has allowed low-volume physicians and centers to achieve outcomes similar to their high-volume counterparts is unknown. OBJECTIVE: To assess the relationship between physician and hospital PCI volumes and patient outcomes following PCIs, given the availability of coronary stents. DESIGN, SETTING, AND PARTICIPANTS: Analysis of data from Medicare National Claims History files for 167 208 patients aged 65 to 99 years who had PCIs performed by 6534 physicians at 1003 hospitals during 1997. Of these procedures, 57.7% involved coronary stents. MAIN OUTCOME MEASURES: Rates of coronary artery bypass graft (CABG) surgery and 30-day mortality occurring during the index episode of care, stratified by physician and hospital PCI volume. RESULTS: Overall unadjusted rates of CABG during the index hospitalization and 30-day mortality were 1.87% and 3.30%, respectively. After adjustment for case mix, patients treated by low-volume (<30 Medicare procedures) physicians had an increased risk of CABG vs patients treated by high-volume (>60 Medicare procedures) physicians (2.25% vs 1.55%; P<.001), but there was no difference in 30-day mortality rates (3.25% vs 3.39%; P =.27). Patients treated at low-volume (<80 Medicare procedures) centers had an increased risk of 30-day mortality vs patients treated at high-volume (>160 Medicare procedures) centers (4.29% vs 3.15%; P<. 001), but there was no difference in the risk of CABG (1.83% vs 1. 83%; P =.96). In patients who received coronary stents, the CABG rate was 1.20% vs 2.78% for patients not receiving stents, and the 30-day mortality rate was 2.83% vs 3.94%. Among patients who received stents, those treated at low-volume centers had an increased risk of 30-day mortality vs those treated at high-volume centers, whereas those treated by low-volume physicians had an increased risk of CABG vs those treated by high-volume physicians. CONCLUSION: In the era of coronary stents, Medicare patients treated by high-volume physicians and at high-volume centers experience better outcomes following PCIs.

The relationship between operator volume and outcomes after percutaneous coronary interventions in high volume hospitals in 1994-1996: the northern New England experience. Northern New England Cardiovascular Disease Study Group.

OBJECTIVES: The purpose of this study was to examine the relationship between annual operator volume and outcomes of percutaneous coronary interventions (PCIs) using contemporaneous data. BACKGROUND: The 1997 American College of Cardiology (ACC)/American Heart Association task force based their recommendation that interventionists perform > or = 75 procedures per year to maintain competency in PCI on data collected largely in the early 1990s. The practice of interventional cardiology has since changed with the availability of new devices and drugs. METHODS: Data were collected from 1994 through 1996 on 15,080 PCIs performed during 14,498 hospitalizations by 47 interventional cardiologists practicing at the five high volume (>600 procedures per hospital per year) hospitals in northern New England and one Massachusetts-based institution that support these procedures. Operators were categorized into terciles based on their annualized volume of procedures. Multivariate regression analysis was used to control for case-mix. In-hospital outcomes included death, emergency coronary artery bypass graft surgery (eCABG), non-emergency CABG (non-eCABG), myocardial infarction (MI), death and clinical success (> or = 1 attempted lesion dilated to < 50% residual stenosis and no death, CABG or MI). RESULTS: Average annual procedure rates varied across terciles from low = 68, middle = 115 and high = 209. After adjusting for case-mix, clinical success rates were comparable across terciles (low, middle and high terciles: 90.9%, 88.8% and 90.7%, Ptrend = 0.237), as were all the adverse outcomes including death (low-risk patients = 0.45%, 0.41%, 0.71%, Ptrend = 0.086; high-risk patients = 5.68%, 5.99%, 7.23%, Ptrend = 0.324), eCABG (1.74%, 2.05%, 1.75%, Ptrend = 0.733) and MI (2.57%, 1.90%, 1.86%, Ptrend = 0.065). CONCLUSIONS: Using current data, there is no significant relationship between operator volumes averaging > or = 68 per year and outcomes at high volume hospitals. Future efforts should be directed at determining the generalizability of these results.

Screening mammography rates by specialty of the usual care physician.

CONTEXT: Although Medicare began paying for screening mammography in 1991, utilization among enrollees has been low. PRACTICE PATTERN EXAMINED: The relation between the specialty of the usual care physician and the proportion of women 65 years of age and older receiving mammography. DATA SOURCE: 100% Medicare Part B claims for 186,526 female enrollees residing in Maine, New Hampshire, and Vermont during 1993 and 1994. RESULTS: Among women of the target screening age (65 to 69 years), 55.4%, received mammography during the 2-year period. The highest rates of mammography were observed in women whose usual care physician was a gynecologist (77.9%; 95% CI, 75.8 to 79.9), followed by those treated by an internist (67.1%; CI, 66.5 to 67.7), family practitioner (58.1%; CI, 57.4 to 58.9), general practitioner (47.4%; CI, 45.4 to 49.5), and other specialists (41.3%; CI, 40.1 to 42.5). The lowest rates were observed in women who had no physician visits during the 2-year period (9.5%; CI, 8.7 to 10.4). Although screening rates were lower in women aged 70 years and older, a similar pattern was observed. CONCLUSIONS: The probability of a Medicare enrollee's receiving screening mammography is strongly influenced by the specialty of her usual care physician. Covering a preventive service does not guarantee its use.

Variation in the use of echocardiography.

CONTEXT: Geographic variation in population-based rates of invasive cardiac procedures has been described. However, little is known about variation in rates of noninvasive testing for cardiovascular disease. Echocardiography is the second most common cardiac diagnostic procedure. PRACTICE PATTERN EXAMINED: Population-based rates of echocardiography, adjusted for age, sex, and race, in the United States. DATA SOURCE: 5% sample of Medicare Part B. RESULTS: 1 in 10 Medicare beneficiaries underwent echocardiography in 1995. Rates of echocardiography varied by state from 5% in Oregon to 15% in Michigan. Rates tended to be lowest in the Northern Great Plains, the Pacific Northwest, and the Rocky Mountains states. Among the 25 largest metropolitan areas, substantial variation was also apparent. For example, one fourth of Medicare beneficiaries in Miami, Florida, received echocardiography, and this proportion was more than four times greater than that seen in Seattle, Washington. CONCLUSION: The likelihood of Medicare beneficiaries having echocardiography is influenced by where they live.

Changing outcomes in percutaneous coronary interventions: a study of 34,752 procedures in northern New England, 1990 to 1997. Northern New England Cardiovascular Disease Study Group.

OBJECTIVES: We sought to evaluate the changing outcomes of percutaneous coronary interventions (PCIs) in recent years. BACKGROUND: The field of interventional cardiology has seen considerable growth in recent years, both in the number of patients undergoing procedures and in the development of new technology. In view of recent changes, we evaluated the experience of a large, regional registry of PCIs and outcomes over time. METHODS: Data were collected from 1990 to 1997 on 34,752 consecutive PCIs performed at all hospitals in Maine (two), New Hampshire (two) and Vermont (one) supporting these procedures, and one hospital in Massachusetts. Univariate and multivariate regression analyses were used to control for case mix. Clinical success was defined as at least one lesion dilated to <50% residual stenosis and no adverse outcomes. In-hospital adverse outcomes included coronary artery bypass graft surgery (CABG), myocardial infarction and mortality. RESULTS: Over time, the population undergoing PCIs tended to be older with increasing comorbidity. After adjustment for case mix, clinical success continued to improve from a low of 88.2% in earlier years to a peak of 91.9% in recent years (p trend <0.001). The rate of emergency CABG after PCI fell in recent years from a peak of 2.3% to 1.3% (p trend <0.001). Mortality rates decreased slightly from 1.2% to 1.1% (p trend 0.007). CONCLUSIONS: There has been a significant improvement in clinical outcomes for patients undergoing PCIs in northern New England, including a significant decline in the need for emergency CABG.

Multivariate prediction of in-hospital mortality after percutaneous coronary interventions in 1994-1996. Northern New England Cardiovascular Disease Study Group.

OBJECTIVES: Using recent data, we sought to identify risk factors associated with in-hospital mortality among patients undergoing percutaneous coronary interventions. BACKGROUND: The ability to accurately predict the risk of an adverse outcome is important in clinical decision making and for risk adjustment when assessing quality of care. Most clinical prediction rules for percutaneous coronary intervention (PCI) were developed using data collected before the broader use of new interventional devices. METHODS: Data were collected on 15,331 consecutive hospital admissions by six clinical centers. Logistic regression analysis was used to predict the risk of in-hospital mortality. RESULTS: Variables associated with an increased risk of in-hospital mortality included older age, congestive heart failure, peripheral or cerebrovascular disease, increased creatinine levels, lowered ejection fraction, treatment of cardiogenic shock, treatment of an acute myocardial infarction, urgent priority, emergent priority, preprocedure insertion of an intraaortic balloon pump and PCI of a type C lesion. The receiver operating characteristic area for the predicted probability of death was 0.88, indicating a good ability to discriminate. The rule was well calibrated, predicting accurately at all levels of risk. Bootstrapping demonstrated that the estimate was stable and performed well among different patient subsets. CONCLUSIONS: In the current era of interventional cardiology, accurate calculation of the risk of in-hospital mortality after a percutaneous coronary intervention is feasible and may be useful for patient counseling and for quality improvement purposes.

Primary cesarean section rates in uninsured, Medicaid and insured populations of predominantly rural northern New England.

Many studies in the United States during the past two decades have reported consistently lower cesarean section rates in women of lower socioeconomic status as defined by census tract, insurance status, or maternal level of educational attainment. This study sought to determine whether cesarean section rates in predominantly rural northern New England are lower for lower, compared with higher socioeconomic groups, as they are reported nationally and in more urban areas. Age-adjusted, primary cesarean section rates for privately insured, Medicaid and uninsured women were calculated using 1990 to 1992 uniform hospital discharge data for Maine, New Hampshire and Vermont. Age-adjusted cesarean section rates for insured women (15.71 percent) were significantly higher than those for Medicaid (14.35 percent) and uninsured (12.85 percent) women. These differences in the cesarean section rate between the insured and poorer populations in northern New England are much less than those reported elsewhere in the country.

Cause of in-hospital death in 12,232 consecutive patients undergoing percutaneous transluminal coronary angioplasty. The Northern New England Cardiovascular Disease Study Group.

BACKGROUND: Some deaths after percutaneous coronary angioplasty (PTCA) occur in high-risk situations (eg, shock), whereas others are unexpected and related to procedural complications. To better describe the epidemiologic causes of death after PTCA, we undertook a systematic review of all in-hospital PTCA deaths in Northern New England from 1990 to 1993. METHODS: The medical records of 121 patients who died during their acute hospitalization for PTCA were reviewed with a standardized data extraction tool to determine a mode of death (eg, low output failure, arrhythmia, respiratory failure) and a circumstance of death (eg, death attributable to a procedural complication, preexisting acute cardiac disease). Any death not classified as a procedural complication was reviewed by a committee and the circumstance of death assigned by a majority rule. RESULTS: Low-output failure was the most common mode of death occurring in 80 (66.1%) of 121 patients. Other modes of death included ventricular arrhythmias (10.7%), stroke (4.1%), preexisting renal failure (4.1%), bleeding (2.5%), ventricular rupture (2.5%), respiratory failure (2.5%), pulmonary embolism (1.7%), and infection (1.7%). The circumstance of death was a procedural complication in 65 patients (53.7%) and a preexisting acute cardiac condition in 41 patients (33.9%). Women were more likely to die of a procedural complication than were men. CONCLUSION: Procedural complications account for half of all post-PTCA deaths and are a particular problem for women. Other deaths are more directly related to patient acuity or noncardiac, comorbid conditions. Understanding why women face an increased risk of procedural complications may lead to improved outcomes for all patients.

Percutaneous transluminal coronary angioplasty in the elderly: epidemiology, clinical risk factors, and in-hospital outcomes. The Northern New England Cardiovascular Disease Study Group.

OBJECTIVES: To explore the relation between older age and clinical presentation, procedural success, and in-hospital outcomes among a large unselected population undergoing percutaneous transluminal coronary angioplasty (PTCA). BACKGROUND: Although more elderly patients are receiving PTCA, studies of post-PTCA outcomes among the elderly have been limited by small numbers and exclusive selection criteria. METHODS: Data were collected as a part of a prospective registry of all percutaneous coronary interventions performed in Maine, New Hampshire, and from 1 institution in Massachusetts between October 1989 and December 1993. Comparisons across 4 age groups, (<60, 60 to 69, 70 to 79, and 80 years and above) were performed using chi-square tests, the Mantel-Haenzsel test for trend, and logistic regression. RESULTS: Twelve thousand one hundred seventy-two hospitalizations for PTCA were performed with 507 of them (4%) in persons at least 80 years old. Octogenarians were more likely to be women, have multivessel disease, high-grade stenoses, and complex lesions but were less likely to have hypercholesterolemia, a history of smoking, or have undergone a previous PTCA. In the elderly, PTCAs were more often performed urgently and for unstable syndromes compared with younger age groups. Advancing age is strongly associated with in-hospital death, and among the oldest old with an increased risk of postprocedural myocardial infarction. Despite differing presentation and procedural priority, angiographic success and subsequent bypass surgery did not vary by age. CONCLUSIONS: With the increasing age of the population at large as well as that segment at risk for cardiac revascularization, information about age-associated risks of the procedure, especially the substantially higher risk of death in octogenarians, will be critical for both physicians and patients considering PTCA.

Potential benefits of regionalizing major surgery in Medicare patients.

CONTEXT: Given the strong "volume-outcome" relations observed with many surgical procedures, concentrating surgery in high-volume hospitals could substantially reduce the number of surgical deaths. We explored the potential benefits of regionalizing 10 high-risk procedures for the 38 million Americans enrolled in Medicare. COUNT: Number of lives saved in 1 year. CALCULATION: Current number of deaths occurring with each procedure multiplied by the average mortality reductions that plausibly could be achieved with regionalization. DATA SOURCE: The current number of surgical deaths was obtained from the 1995 MEDPAR file of the Medicare claims database. Expected mortality rate reductions with regionalization, estimated from published volume-outcome studies, were tested over a wide range in sensitivity analysis. RESULTS: Of 381,000 Medicare patients undergoing any 1 of the 10 procedures in 1995, approximately 17,000 surgical deaths occurred. The total number of lives saved by regionalization depends on assumptions about the mortality reductions likely to be achieved, varying from 853 (5% reduction) to 4266 (25% reduction). Regionalizing common, intermediate-risk procedures (e.g., cardiovascular procedures) would save far more lives than regionalizing less-common, higher-risk operations (e.g., major cancer resections). CONCLUSIONS: Even with conservative assumptions about reduction in surgical mortality likely to be achieved, the benefits of regionalizing major procedures in Medicare patients could be substantial. Policymakers should focus on common procedures before less-common, high-risk operations.

Physician partnering in Maine: an update from the Maine Medical Assessment Foundation.

BACKGROUND: The Maine Medical Assessment Foundation (MMAF) has involved the participation of hundreds of physicians in study groups to analyze data on small-area variation and assess physician decision-making patterns. In 1991 the MMAF model was replicated across a tri-state area (Maine, New Hampshire, and Vermont) in an effort called the Outcomes Dissemination Project. THE OUTCOMES DISSEMINATION PROJECT: Five specialty study groups, each meeting three times a year, examined local and national utilization data and guidelines and research findings, participated in outcomes studies and patient education, and disseminated their findings through society presentations and other feedback efforts. Physician surveys indicated that all but one of the study groups were successful in making their existence and activities known to the broader medical community. PARTNERING WITH PURCHASERS AND MEDICAID: In the "Partnership Projects," the MMAF and relevant study groups, collaborating with a Maine business coalition, analyzed variations in utilization across employers, types of health plans (for example, health maintenance organization, preferred provider organization, fee-for-service), and small areas. Through this process, coalition members learned about small-area analysis and the implications of variations in utilization for cost and quality. The first year of the collaborative projects focused on several issues, including the development and dissemination of a practice guideline for the care of patients with chest pain; the dissemination of a practice guideline for the treatment of patients with acute low back pain; and a project designed to address cesarean section rates. SUMMARY: Innovative partnerships have been crafted to allow the tenets of the MMAF's working relationships with the medical community to remain intact, ensuring the ongoing interest and cooperation of hundreds of Maine physicians.

Carotid endarterectomy after NASCET and ACAS: a statewide study. North American Symptomatic Carotid Endarterectomy Trial. Asymptomatic Carotid Artery Stenosis Study.

PURPOSE: Since the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and the Asymptomatic Carotid Artery Stenosis Study (ACAS) established the efficacy of carotid endarterectomy at large academic centers, there have been two community-based studies of outcomes after this operation. The purpose of this study was to perform a statewide survey to evaluate postoperative morbidity and mortality after carotid endarterectomy among patients throughout Maine. METHODS: A statewide registry was established to collect prospective data on carotid operations from January 1 to December 31, 1995. All surgeons and hospitals in the state were solicited to participate. All carotid endarterectomies were intended to be included; the only exclusion criterion was out-of-state residence. Comorbidities, preoperative studies, surgical indications, operative technique, and postoperative outcomes were analyzed. State administrative data were used to assess registry coverage. RESULTS: Ten of 17 hospitals participated, and 58% of all carotid endarterectomies performed in the state were included. Three hundred sixty-four operations were entered into the registry. Forty-four percent of the operations were performed for transient ischemic attack, 37% for asymptomatic stenosis, and 19% for stroke. The postoperative stroke rate was 2.5% with a total neurologic complication rate of 4.7% (transient ischemic attack and stroke). There was one postoperative death (mortality rate 0.3%). Patients with symptoms had a higher incidence of postoperative stroke (4.0% vs 0% asymptomatic; p < 0.05) and transient ischemic attacks (3.8% vs 0.8% asymptomatic). Hospital stroke rates varied from 0% to 7%. Stroke rate did not differ significantly between low-volume hospitals (2 to 28 patients/year, 3.3%) and high-volume hospitals (29 to 101 patients/year, 2.3%) or between low-volume surgeons (fewer than 11 operations/year, 1.7%) and high-volume surgeons (more than 12 operations/year, 2.4%). Among 26 reporting surgeons, stroke rate varied from 0% to 10%; the absolute number of strokes per surgeon varied between zero and two. CONCLUSION: The statewide registry showed a postoperative stroke plus death rate of 2.8%, comparable with the NASCET and ACAS findings. Although this study had inherent limitations, the results from one state, including a variety of community practices, achieved results comparable with those of landmark trials.

Variation in carotid endarterectomy mortality in the Medicare population: trial hospitals, volume, and patient characteristics.

CONTEXT: The North American Symptomatic Carotid Endarterectomy Trial (NASCET) and the Asymptomatic Carotid Atherosclerosis Study (ACAS) demonstrated the efficacy of carotid endarterectomy (CEA) in reducing the risk of stroke and death in selected patients when surgery was performed in institutions whose participation depended on demonstrated excellence. Thirty-day mortality rates in the trials were very low: 0.6% in NASCET and 0.1% in ACAS. OBJECTIVE: To assess perioperative mortality among Medicare patients undergoing CEA in all nonfederal institutional settings. DESIGN: Retrospective national cohort study. SETTING AND PATIENTS: All 113300 Medicare patients undergoing CEA during 1992 and 1993 in "trial hospitals" (those participating in NASCET and ACAS, n=86) and "nontrial hospitals" (all other nonfederal institutions performing CEAs, n=2613). Nontrial hospitals were stratified into terciles based on volume of CEAs performed. MAIN OUTCOME MEASURES: Crude and adjusted perioperative (30 day) mortality rates. RESULTS: The perioperative mortality rate was 1.4% (95% confidence interval [CI], 1.2%-1.7%) at trial hospitals; mortality in nontrial hospitals was higher: 1.7% (95% CI, 1.6%-1.8%) (high volume); 1.9% (95% CI, 1.7%-2.1 %) (average volume); 2.5% (95% CI, 2.0%-2.9%) (low volume); (P for trend, <.001). In multivariate modeling, patients undergoing their procedures at trial hospitals had a mortality risk reduction of 15% (95% CI, 0%-31%) compared with high-volume nontrial hospitals, 25% (95% CI, 7%-40%) compared with average-volume hospitals, and 43% (95% CI, 25%-56%) compared with low-volume hospitals (P for trend, <.001). CONCLUSION: Medicare patients' perioperative mortality following CEA is substantially higher than that reported in the trials, even in those institutions that participated in the randomized studies. Caution is advised in translating the efficacy of carefully controlled studies of CEA to effectiveness in everyday practice.