Cardiac Surgery in New Jersey
1996 - 1997

March 1999

Message From the Commissioner

We are pleased to present Cardiac Surgery in New Jersey, 1996 - 1997, the state's second consumer report on coronary artery bypass graft surgery. This report summarizes the results of a study which compares patient mortality rates for the hospitals and physicians performing bypass surgery.

Patients facing bypass surgery, as well as their families, usually have many questions and concerns. This guide answers some of those questions and provides comparative data on the performance of cardiac surgeons and hospitals offering cardiac surgery. We hope this guide will help consumers discuss their concerns and treatment options with their physicians.

I would like to thank the Cardiovascular Health Advisory Panel for its ongoing commitment to this important project. This select group of experts -- which includes physicians who specialize in cardiac surgery, cardiologists and other health care professionals -- has worked collaboratively with the Department to develop meaningful data in which consumers and providers can have confidence. The Data Quality Improvement Committee, with representatives from all the hospitals performing cardiac surgery, also has provided important assistance with this project. We all share the same goal: to ensure the high quality of cardiac surgery in New Jersey.


This guide is for patients and families of patients considering coronary artery bypass graft (CABG) surgery. It provides mortality rates for the 13 hospitals and 50 physicians performing this common surgical procedure during 1996 and 1997.

For this study, the Department of Health and Senior Services collected data on the 16,548 patients who had bypass surgery. All data have been "risk-adjusted," which means the data were adjusted to take into account the patient's health condition before surgery. This risk-adjustment allows for fair comparisons among hospitals and surgeons treating diverse patient populations.

For 1996-1997, the statewide risk-adjusted mortality rate following bypass surgery was 3.37 percent. This is more than a 10 percent decline over the period 1994-1995, when the rate was 3.75 percent. This decline occurred at the same time that the number of bypass surgeries performed statewide has increased.

An important goal of this study is to give hospitals and surgeons data they can use in assessing quality of care related to bypass surgery. There is strong evidence, from the handful of states with similar studies, that this information encourages hospitals to examine their procedures and make changes that can improve quality of care and, ultimately, save lives. New Jersey's risk-adjusted mortality rate for bypass surgery should show a steady decline as the Department continues to publish this report.

Another goal is to give patients and physicians information to use in discussing questions related to bypass surgery. Please remember that the numbers in this guide are just one factor to consider when choosing a hospital or surgeon. The patient and physician together can make the best choice after full consideration of that patient's medical needs. Also note that data in this guide are from 1996 and 1997. These data may not reflect current performance, as hospitals may have revamped their programs, or individual surgeons may have left the hospitals at which they practiced.

Heart Disease and Cardiac Surgery in New Jersey

Heart disease is the single largest killer of Americans. About every 20 seconds a person somewhere in this country will suffer a heart attack, and about once every minute someone will die from one. In New Jersey, cardiovascular disease, including heart disease, is the leading cause of death.

The most common form of heart disease is coronary artery disease. It occurs when the coronary arteries, which carry blood to the heart muscle, become clogged or partially blocked by fatty deposits on the artery walls. This can lead to chest pain, or angina, which is a warning sign for a heart attack. A heart attack occurs when a coronary artery is totally blocked.

Treatment Options

Treatment for coronary artery disease will vary for different patients. The choice of treatment depends on the nature and severity of the disease and other factors unique to each patient.

For some patients, lifestyle changes such as quitting smoking, eating a low-fat diet, and getting more exercise may be enough. Some patients require special medications. Others may need medical procedures such as angioplasty or coronary artery bypass graft surgery. Angioplasty reduces obstructions of fatty deposits in coronary arteries. Bypass surgery uses an artery or vein taken from another part of the body to divert blood around the clogged part of a patient's artery or arteries.

This guide is about coronary artery bypass graft surgery. It will help you learn about the performance records of 13 hospitals in New Jersey that offer this type of surgery and 50 surgeons who perform this complex operation. This guide will also help you begin talking with your doctor about bypass surgery. You and your doctor should make decisions after taking all available information into account.

Performance Data

In 1996-97, there were 16,548 isolated bypass surgeries performed in New Jersey. In an isolated bypass surgery, no other major heart procedure is performed at the same time. The number of people who died in the hospital during or after isolated bypass surgery was 557.

In evaluating the performance of hospitals and surgeons, it would be unfair to make comparisons only on the basis of how many patients died. The mortality risk for patients undergoing bypass surgery varies significantly with how healthy patients are prior to surgery. For instance, a 75-year-old woman, who has diabetes and had previous open heart surgery, would be at higher risk for this surgery than a 50-year-old, non-smoking man who had no history of chronic disease.

In order to produce fair comparisons, the New Jersey Department of Health and Senior Services developed a methodology that reports risk-adjusted mortality rates. The risk-adjusted mortality rate gives hospitals and surgeons who operate on sicker patients extra credit, so that they won't be at a disadvantage in the performance comparisons.

Each hospital was required to submit data which were used to create a risk profile for each patient undergoing bypass surgery. Key factors that influence a patient's chance of surviving the operation include:

Weights were assigned for each of these factors and calculations were performed for each hospital and surgeon to produce risk-adjusted mortality rates as a fairer basis of comparison.

Performance Reports Lead to Improvement

This performance report can be used not only by you and your doctor, but also by hospitals and surgeons to improve the quality of their care and their patients' outcomes. Evidence from other states that have published similar performance reports shows that mortality rates have declined and the overall quality of bypass surgery care has improved substantially. The Department of Health and Senior Services intends to continue to publish performance reports on cardiac surgery to promote steady improvement in the state's mortality rate.


Only 14 hospitals in New Jersey were licensed to perform coronary artery bypass surgery in the 1996-1997 reporting period. One of these hospitals, St. Francis Medical Center in Trenton, was newly licensed and did not begin performing surgery until 1998. This booklet provides risk-adjusted mortality rates for the remaining 13 hospitals. You will see that there are variations among the hospitals. Through statistical analysis, the Department is able to determine in which cases the differences are not a matter of chance, but reflect real differences in performance. Nevertheless, this data should not be used as the sole factor in making choices about hospitals, but should be part of the discussion between you and your doctor.


A risk-adjusted mortality rate was also calculated for each of the 50 surgeons who performed at least 100 bypass operations in one hospital during 1996-97. Statistics for surgeons who performed fewer than 100 operations during this period are grouped under the hospital where the operations took place, in an All Others category. These surgeons are not listed by name because they did not perform the minimum number of procedures necessary for the Department to have confidence in the results of the analysis. For these low-volume surgeons, therefore, risk-adjusted mortality rates are not necessarily an accurate indication of their individual performance.

Volume Affects Quality

Many studies nationally and in other states have shown that, in general, hospitals and surgeons that perform bypass surgery more frequently have lower patient mortality rates. However, some surgeons and hospitals with high volumes have relatively higher mortality rates, while others with low volumes have lower mortality rates. As a group, low-volume surgeons in New Jersey (those who performed fewer than 100 procedures in 1996-97) had a significantly higher mortality rate than the state average.

In 1998, the Department adopted regulations requiring hospitals to assure that each of its surgeons perform a minimum of 100 procedures a year at that hospital by the year 2001.

Bypass Surgery Volume at New Jersey Hospitals

Figure 1: Number of Isolated Coronary Artery Bypass Graft Surgeries, 1996-97. This figure shows how many bypass operations were performed in each hospital in the two-year period 1996-97. You can see that some hospitals do more of these procedures than others, with totals ranging from 222 at University Hospital to 2,239 at Morristown Memorial Hospital.

Figure 1

Statewide Performance Data

The average risk-adjusted mortality rate for the state was 3.37 percent in 1996-97. This is more than a 10 percent decline over the period 1994-1995, when the rate was 3.75 percent. At the same time, the number of surgeries increased from 14,510 to 16,548.

Individual Hospital Performance

Figure 2: Hospital Risk-Adjusted Mortality Rates, 1996-97. This shows the risk-adjusted mortality rate for each hospital in New Jersey performing bypass surgery in 1996-1997. The risk-adjusted mortality rate takes into account both the patients' risk factors going into surgery and the actual mortality rate of patients in the hospital.

On the graph, the vertical line represents New Jersey's statewide mortality rate of 3.37 percent. Each hospital's performance is displayed graphically in relation to this statewide average.

Figure 2 shows that three hospitals have a gray bar completely to the left of the statewide average line -- Hackensack University Medical Center, Morristown Memorial Hospital and The Valley Hospital. This means these hospitals' mortality rates were significantly below the statewide average, according to the rules of statistics.

Four hospitals -- Jersey Shore Medical Center, Newark Beth Israel Medical Center, Our Lady of Lourdes Medical Center and St. Michael's Medical Center -- have bars completely to the right of the line. That means their mortality rates were significantly above the statewide average.

The remaining six hospitals have bars that touch the average line. That means that their rates were no different than the statewide average.

Figure 2

Statistical Significance

In trying to determine a hospital's or a surgeon's performance, it is important to account for the fact that some differences occur simply due to luck or random variation. Statistical tests are conducted on data so that we can be as certain as possible that the differences are due to actual differences in performance. A difference is called "statistically significant" when it is large enough that it is not likely due to luck or random variation.

The black circle on each provider's gray bar represents the calculated risk-adjusted mortality rate. However, we can't really be certain that number is the precise rate. We can only be relatively sure that the true rate falls somewhere on the gray bar. In analyzing data, we use what is called a "95 percent confidence interval," and the gray bar represents this confidence interval. We are 95 percent confident that the hospital's or surgeon's true risk-adjusted mortality rate falls within the range shown by the bar. Another way of saying it is that the bar represents the statistical margin of error for the calculation of that rate.

When using this report, it is important to remember that the charts are designed to show whether a provider's risk-adjusted mortality rate is significantly above or below the statewide rate, or whether a rate is statistically the same as the statewide rate. Thus, it is more important to view the bars in relation to the average line than it is to examine the individual calculated rates, or circles on the bars. The chart should not be used to make hospital-to-hospital, or surgeon-to-surgeon comparisons, only to compare hospitals or surgeons against the statewide rate.

In examining the charts, you will see that some gray bars are shorter than others. The bar is shorter for hospitals and surgeons performing more surgeries, and longer for those with lower volumes. This reflects the fact that larger numbers -- in this case, more surgeries -- increase the precision of a statistic.

Surgeon Performance

Figure 3: Surgeon Risk-Adjusted Mortality Rates, 1996-97. This graph shows the risk-adjusted mortality rate for each of 50 surgeons who performed at least 100 isolated bypass surgery operations in at least one hospital in New Jersey in 1996-97.

This chart expands on the previous one, listing surgeons by name under the hospital at which they practice. Following the named surgeons, some hospitals have a category "All Others," which includes all surgeons not performing enough procedures to be included in the analysis. In addition, the hospitals' risk-adjusted mortality rates are repeated at the end of each hospital entry.

As in Figure 2, this graph shows which surgeons' risk-adjusted mortality rates were statistically significantly different from the statewide average, and which were the same as the state average. Again, surgeons whose gray bars touch the statewide average lines have rates that are not statistically significantly different from the statewide average.

Figure 3

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Questions and Answers

These are some commonly asked questions that may be of interest to you as you read this booklet.

Q: Should I go only to the hospitals or surgeons with below-average risk-adjusted mortality rates?

A: Not necessarily. There are many factors to consider in determining the best hospital and surgeon for you. Among these are your own personal risk factors and the experience certain hospitals and surgeons have treating patients with those risk factors. Before making up your mind, you should discuss this report with the physician, usually a cardiologist, who refers you for cardiac surgery. The cardiologist's knowledge and expertise will be a valuable guide in your decision making. You should also keep in mind that the data in this guide are from 1996-97 and that hospitals' and surgeons' performance may have changed since then.

Q: Why doesn't the report contain data for surgeons who performed fewer than 100 bypass operations in 1996-97?

A: When a surgeon performs a relatively small number of procedures, it is difficult to give a statistically precise estimate of that surgeon's performance. As a result, the Department has omitted individual data for this group. However, as a group, low-volume surgeons had a significantly higher mortality rate than the state average.

Q: Does that mean that I should avoid any surgeon whose name is not included in this report?

A: No, not necessarily. First, there are lower volume surgeons with good patient outcomes. Second, there may be a good reason why a surgeon had a low volume. For example, the surgeon might be beginning his/ her career or has recently moved from another state, where he/she performed a high volume of these procedures. It is best to discuss your concerns with your referring doctor.

Q: Is it better to go to a hospital with a high volume of cases and a surgeon who handles a large number of cases?

A: National studies have demonstrated that, in general, hospitals and surgeons with higher volume have better results. However, some surgeons and hospitals with high volumes have relatively high mortality rates, while others with low volumes have lower mortality rates.

Notes on Data:

The data used in this study were reported by hospitals according to criteria established by the Department, with assistance from the Cardiovascular Health Advisory Panel (CHAP). The panel includes doctors who specialize in cardiac surgery and cardiology, and other health care professionals. The data were audited by the independent Peer Review Organization of New Jersey.

Also providing oversight on data quality and consistency were the Data Quality Improvement Committee, which includes representatives from all the hospitals performing cardiac surgery, and the Commissioner's Clinical Panel.

Throughout the process of developing this report, the Department has taken steps to make sure that all hospitals were informed about data reporting and auditing requirements, as well as the statistical methods being used to risk-adjust the reported mortality data.

The Department considers it a vital function of hospitals to be able to collect and report complete, accurate medical information on patients. This function is critical not only to the success of the cardiac surgery report, but to the hospitals' own ongoing efforts to improve the quality of care for all patients. The Department and hospitals will continue working to improve data collection procedures so that this report contains the best possible information.

This document may only be reproduced in its entirety. No portion of this document may be reproduced without the permission of the New Jersey Department of Health and Senior Services.

© 1999 New Jersey Department of Health and Senior Services

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