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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Operator volume and outcomes in 12,998 percutaneous coronary interventions. Northern New England Cardiovascular Disease Study Group

OBJECTIVES

We sought to determine whether there is a relation between operator volume and outcomes for percutaneous coronary interventions (PCIs).

BACKGROUND

A 1993 American College of Cardiology/American Heart Association task force stated that cardiologists should perform > or = 75 procedures/year to maintain competency in PCIs; however, there were limited data available to support this statement.

METHODS

Data were collected from 1990 through 1993 on 12,988 PCIs (12,118 consecutive hospital admissions) performed by 31 cardiologists at two hospitals in New Hampshire and two in Maine and one hospital in Massachusetts supporting these procedures. Operators were categorized into terciles based on annualized volume of procedures. Univariate and multivariate regression analyses were used to control for case-mix. Successful outcomes included angiographic success (all lesions attempted dilated to < 50% residual stenosis) and clinical success (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 (MI) and death.

RESULTS

After adjustment for case-mix, higher angiographic (low, middle and high terciles: 84.7%, 86.1% and 90.3%, p-trend 0.006) and clinical success rates (85.8%, 88.0% and 90.7%, p-trend 0.025), with fewer referrals to CABG (4.54%, 3.75% and 2.49%, p-trend <0.001), were seen as operator volume increased. There was a trend toward higher MI rates for high volume operators (2.00%, 1.98% and 2.57%, p-trend 0.06); all terciles had similar in-hospital mortality rates (1.09%, 0.96% and 1.05%, p-trend 0.8).

CONCLUSIONS

There is a significant relation between operator volume and outcomes in PCIs. Efforts should be directed toward understanding why high volume operators are more successful and encounter fewer adverse outcomes.

Changing physician behavior: the Maine Medical Assessment Foundation

Methods to produce change in physician practice patterns are of increasing importance to payers and regulators as well as to physicians themselves. Because some of the strategies being adopted occur without physician input and participation, they have aroused concern in the medical community. We describe the methods used and results achieved by the Maine Medical Assessment Foundation, a nonprofit education and research organization, that has been active in practice pattern analysis since the late 1970s. The foundation has successfully engaged clinicians in a program of systematic assessment of medical care provided to residents of Maine. Significant change in practice patterns has been documented. Physicians have become active participants in the process of voluntary self-assessment, education, and quality improvement.

Utilization patterns of cord blood gas analysis

OBJECTIVE

To determine patterns of use of cord blood gas analysis in two institutions in Portland, Maine; to determine which factors, if any, predicted use of the test; and to evaluate compliance with ACOG guidelines.

METHODS

Billing data were used from 3166 deliveries during 1994 in the two hospitals to find deliveries in which the test was performed. We merged billing data with birth certificate data to examine factors associated with the test's use. Finally, we compared its use in our community with recently updated ACOG guidelines.

RESULTS

There was a 20-fold difference in the test's use between institutions (P < .001). The test was performed in 49% of all births at the tertiary care center and 2.5% of births at the community hospital. Many maternal and neonatal factors were linked to use of the test, but delivery system factors, in particular, the institution, were the strongest predictors of the test's use, even controlling for confounding factors between hospitals. There was little adherence to ACOG guidelines, with 97% of the tests being performed in situations in which ACOG's recommendations did not support use of the analysis.

CONCLUSION

Current use of cord blood gas analysis in our community is not consistent with guidelines or cost-effective use of resources; the institutional factors that determine excess use should be examined and modified.

Antibiotic optimization. An evaluation of patient safety and economic outcomes

BACKGROUND

Although numerous reports have described interventions designed to influence antibiotic utilization, to our knowledge none have been evaluated in a randomized study.

METHODS

Adult inpatients receiving 1 or more of 10 designated parenteral antibiotics for 3 or more days during a 3-month period were randomized to an intervention (n = 141) and a control (n = 111) group using an unblocked, computer-generated random number table. Obstetric patients and those seen in infectious disease consultation were excluded. The intervention group received antibiotic-related suggestions from a team consisting of an infectious disease fellow and a clinical pharmacist. Both groups were evaluated for clinical and microbiological outcomes as well as antibiotic utilization via prospective chart reviews and analysis of the hospital's administrative database.

RESULTS

Sixty-two (49%) of the intervention group patients received a total of 74 suggestions. Sixty-three (84%) of these suggestions were implemented; the majority involved changes in antibiotic choice, dosing regimen, or route of administration. Per patient antibiotic charges were nearly $400 less in the intervention group vs controls (P = .05). Almost all the savings were related to lower intravenous antibiotic charges. Clinical and microbiological response, antibiotic-associated toxic effects, in-hospital mortality, and readmission rates were similar for both groups. Multiple linear regression analysis identified randomization to the intervention group and female sex as the sole predictors of lower antibiotic charges. There was a trend toward a shorter length of stay for the intervention group (20 vs 24.7 days, P = .11).

CONCLUSIONS

This is the first randomized study to evaluate whether antibiotic choices can be influenced in a cost-effective fashion without sacrificing patient safety. We demonstrate that 50% of patients initially treated with expensive parenteral antibiotics can have their regimens refined after 3 days of therapy and that these modifications result in good clinical outcomes with a substantial reduction in antibiotic expense.

Do physicians do what they say? The inclination to test and its association with coronary angiography rates

OBJECTIVE

Efforts to evaluate variations in cardiac procedures have focused on patient factors and differences in health care delivery systems. We wanted to assess how physicians' inclination to test patients with coronary artery disease influences utilization patterns.

SETTING AND SUBJECTS

Physicians and the populations of Maine, New Hampshire, and Vermont.

DESIGN

We conducted a survey of 263 family practitioners, internists, and cardiologists residing in 57 hospital service areas in Maine, New Hampshire, and Vermont. Using patient scenarios, we assessed the clinicians' inclinations to test during the evaluation of patients with coronary artery disease. Self-reported testing intensities were used to create three indices: a Catheterization Index, an Imaging Exercise Tolerance Test (ETT) Index, and Nonimaging ETT Index. Using administrative data, age- and gender-adjusted population-based coronary angiography rates were calculated. Physicians were assigned to low (2.9/1,000), average (4.2/1,000), and high (5.8/1,000) coronary angiography rate areas, based on where they practice. Analysis of variance techniques were used to assess the relation of the index scores to the population-based coronary angiography rates and to physician specialties.

RESULTS

There was a positive relationship between the population-based coronary angiography rates and the self-reported scores of the Catheterization Index (p < .005) and the Imaging ETT Index (p = .01), but none was found for the Non-imaging ETT Index (p = .10). These relationships were evident in subanalyses of cardiologists and internists, but not of family practitioners.

CONCLUSIONS

Self-reported testing intensity by physicians is related to the population-based rates of coronary angiography. This relationship cuts across specialties, suggesting that there is a "medical signature" for the evaluation of patients with coronary artery disease.

The use of Medicare home health care services

BACKGROUND

Medicare's home health care program, consisting primarily of home visits by nurses and health aides, was conceived as a means to facilitate hospital discharge. Because home health care is now one of the fastest-growing categories of Medicare expenditures, we analyzed Medicare claims data to determine current patterns of use.

METHODS

We used 1993 data from Medicare's National Claims History File to examine the temporal relation between home visits and hospital discharge, as well as the number of months Medicare enrollees received home health care. To determine whether home visits replaced hospital services, we calculated population-based utilization rates, adjusted for age and sex, for enrollees living in the 310 U.S. metropolitan statistical areas and determined whether the areas with higher rates of home health care also had lower admission rates or shorter lengths of stay. Finally, we compared the geographic variation in use of home health care with that of other Medicare services.

RESULTS

Roughly 3 million Medicare enrollees received over 160 million home health care visits in 1993. Seventy-eight percent of the visits either occurred more than a month after hospital discharge (35 percent) or were not associated with any inpatient care during the previous six months (43%). Home health care often represented a long-term intervention: 61 percent of the visits were to enrollees who received home health care for six months or more. We could find no evidence that home health care was substituted for hospital care; the metropolitan statistical areas with higher rates of home health care did not have fewer hospital admissions or shorter lengths of stay. There was more geographic variation in the use of home health care than in the use of other major categories of Medicare services (e.g., hospital admissions and physicians' services). Five states (all in the South) had more than 9000 visits per 1000 enrollees, and 14 states had fewer than 3000 visits per 1000 enrollees.

CONCLUSIONS

Home health care visits are used primarily to provide long-term care. There is no evidence that services provided at home replace hospital services, and the dramatic geographic variation in home visits suggests a lack of consensus about their appropriate use.

Changing physician behavior in ordering digoxin assays

OBJECTIVE

To assess the ability to modify physicians' use of serum digoxin assays in a sustained fashion through (1) an educational intervention by a clinical pharmacist, and (2) changes in the computerized medical information system.

DESIGN

A before/after methodology was used to compare test use by hospital staff physicians in two phases. Phase 1 was an educational intervention conducted by a clinical pharmacist with an 8-month follow-up. Phase 2 was a medical information system intervention with a 12-month follow-up.

PATIENTS

Adult inpatients from July 1990 through December 1993 who received either digoxin therapy or at least one serum digoxin assay.

MAIN OUTCOME MEASURE

Digoxin assays per patient day while receiving digoxin (assays/digoxin day), in-hospital mortality, and length of stay were compared before and after implementation of the interventions.

RESULTS

A total of 9468 patients received a digoxin and/or serum digoxin assay. Baseline use of serum digoxin assays was 0.178 assays/digoxin day. Following phase 1, the educational intervention, use declined 20.2% to 0.142 assays/digoxin day (p < 0.03). After phase 2, the implementation of changes in the medical information system, digoxin assay use was maintained at 16.3% less than that at baseline (p < 0.03). Patient mortality was unaffected.

CONCLUSIONS

A low-intensity educational intervention by a clinical pharmacist supplemented by medical information system modification resulted in an important decrease in the use of digoxin assays. The change in physician behavior was sustained for more than 18 months. The model presented is not labor intensive, does not require continuous maintenance by healthcare personnel for a sustained effect, and may be widely applicable to healthcare providers.

The association between local diagnostic testing intensity and invasive cardiac procedures

OBJECTIVE

To determine the extent to which geographic variation in invasive cardiac procedures can be explained by the variable use of diagnostic testing.

DESIGN

A population-based cohort study using Medicare Part B data (physician services).

SETTING AND SUBJECTS

Procedure data for all Medicare beneficiaries in northern New England.

MAIN OUTCOME MEASURES

Twelve coronary angiography service areas were constructed for Medicare beneficiaries in northern New England. Age- and sex-adjusted utilization rates were developed for three procedure categories: total stress test, coronary angiography, and revascularization. Total stress tests were further stratified into nonimaging and imaging procedures (eg, thallium). Tests performed in follow-up to invasive procedures were excluded (eg, stress test following revascularizations). Linear regression was used to assess the relationship between procedure categories.

RESULTS

A tight positive relationship was found between total stress test rates and the rates of subsequent coronary angiography (R2=0.61, P<.005). Most of the variance was explained by imaging stress tests (R2=0.50, P<.02). A strong relationship was found between coronary angiography and revascularization (R2=0.82, P<.001). Finally, a clear relationship between total stress tests and subsequent revascularizations was also found (R2=0.55, P<.006).

CONCLUSION

The population-based rates of diagnostic testing largely explained the variance associated with subsequent therapeutic interventions. Our results suggest that local testing intensity is an important determinant of the variable use of invasive cardiac procedures.

Partnering with physicians to achieve quality improvement

BACKGROUND

The Maine Medical Assessment Foundation (MMAF) has successfully involved hundreds of Maine 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, Vermont) in an effort called the Outcomes Dissemination Project, which is funded by a five-year grant from the U.S. Agency for Health Care Policy and Research.

THE OUTCOMES DISSEMINATION PROJECT

Five specialty study groups, each meeting three times a year, examine local and national utilization data, examine guidelines and research findings, participate in outcomes studies and patient education, and disseminate their findings through specialty society presentations and other feedback efforts. The MMAF study group process is based on the beliefs that medicine is a subculture with a complex set of professional values, beliefs, socialization processes, and norms, and that quality improvement efforts work best when they are nonpunitive and educational.

ISSUES IN OBTAINING PHYSICIAN INVOLVEMENT

(1) Physicians are willing to change their practices if they are brought into a culturally appropriate improvement program. (2) Related specialties (for example, internists and family practitioners) can often work together effectively on issues of common interest. (3) Involving respected clinical leaders has helped establish the legitimacy of MMAF methods among physicians. (4) Area- and physician-specific data are not made public, so as to build a sense of confidentiality among participants.

CONCLUSIONS

The project continues to function as a powerful education process and serves as a model for replication elsewhere.