Monday, 23 February 2015

New study finds same patient mortality rates for experienced and new surgeons




There is no statistical difference between the patient mortality rates of new and experienced surgeons a study using a newly developed statistical methodology and conducted by a research team comprised of medical doctors and statisticians has found.


Because was radically changed in recent years—including a reduction of six to 12 months of training time—and other factors, the research team said further study will be needed to ensure the findings generalize.


Researchers involved in this study are Dr. Rachel R. Kelz, associate professor of surgery; Dr. Jeffrey Silber, professor of pediatrics, anesthesiology and critical care; Paul Rosenbaum, professor of statistics; and Sam Pimentel, a doctoral student in statistics—all of the University of Pennsylvania.


The study recently was published on the website of the Journal of the American Statistical Association , a publication of the nation's oldest and largest organization of professional statisticians.


For the study, the research team accessed a Medicare database from several states covering a period of two years to create two matched groups of surgical patients. The data consisted of 130,106 patients who were operated on in 498 hospitals. The two groups created through the matching process consisted of 6,260 each and were similar in 2.9 million categories. For example, each group had the same number of patients who received each surgical procedure (i.e., knee replacement, appendectomy). Additionally, among patients who received a particular procedure, the numbers of patients who had a particular pre-existing condition (i.e., diabetes, past stroke, and ) also were as close as possible across the two groups. "Matching" patients in this way makes it easier to compare the clinical outcomes of the two groups.


Following its analysis of the data for each patient group, the researchers found that the mortality rate for patients of experienced surgeons was 3.59% (225 deaths out of 6,260 surgeries), while the mortality rate of new surgeons was 3.71% (232 deaths out of 6,260 surgeries).


"It is reassuring that new surgeons were able to achieve similar mortality rates to experienced surgeons when caring for similar patients. However, mortality is a relatively rare event that may not expose the benefits of experience," said Dr. Kelz. "Therefore, future studies focused on additional outcomes are needed to ensure that new surgeon training and transition to independent practice are appropriately structured to meet the surgical needs of the public."


Among the factors that require further analysis are the following:



  • First, because new surgeons trained under the shortened training model only recently have entered the nation's health care system, further analysis will determine if the findings will generalize to patient outcomes of experienced and new surgeons following the reduction in the training time.

  • Also, the research team compared outcomes across multiple surgical specialties to demonstrate the feasibility of the new statistical methodology. More patients are needed to examine clinically relevant subsets of patients and to examine additional important outcomes such as post-operative complications and health care costs.

  • Last, the pilot data used for the analysis was limited and thus narrows the generalizability of the study's findings. The researchers have applied for funding to run a broader analysis to see if the patient outcomes of new and experienced surgeons do, in fact, generalize.


"Mandates changing professional education often are implemented without a method to investigate the downstream effects on the population health. This new methodology can be used in a larger study to examine the important question of whether new and experienced surgeons achieve equivalent outcomes following the mandated changes in the training paradigm. Additionally, the methodological framework we establish can be used to monitor the effects of subsequent changes to the health care workforce on patient outcomes across a variety of practice settings and clinical conditions," wrote the researchers.


The new statistical methodology used in this study—called "large, sparse optimal matching"—was developed because patients typically are assigned to surgeons in a nonrandom manner. As a result, there may be systematic differences between the patients of recent surgical graduates and experienced surgeons, making measurement of surgeon effects difficult. For instance, within the pilot data, newly trained surgeons tended to operate on a different mix of patients than experienced surgeons. The patients of new surgeons more often were admitted via the emergency room and had higher risk factors on average. Other differences include the severity of a patient's illness and risk of mortality across patients.


In the study, the statistical matching method accounted for these discrepancies and allowed researchers to make fairer comparisons between similar groups of patients. Once the initial discrepancies were removed, researchers no longer observed any significant mortality difference between the two groups.


The new techniques developed for this study have tremendous promise to enable large-scale comparisons across a variety of settings and populations with appropriate control for differences in patient cohorts that was not previously possible.


"The new methodology will make it much easier to create good matches from large medical data sets," said Pimentel. "Large, sparse optimal matching will be useful in contexts outside of clinical medicine, too, including education research and public health, and I'm excited to see what other scientific questions it can help answer."




Provided by American Statistical Association



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There is no statistical difference between the patient mortality rates of new and experienced surgeons a study using a newly developed statistical methodology and conducted by a research team comprised of medical doctors and statisticians has found.


Because was radically changed in recent years—including a reduction of six to 12 months of training time—and other factors, the research team said further study will be needed to ensure the findings generalize.


Researchers involved in this study are Dr. Rachel R. Kelz, associate professor of surgery; Dr. Jeffrey Silber, professor of pediatrics, anesthesiology and critical care; Paul Rosenbaum, professor of statistics; and Sam Pimentel, a doctoral student in statistics—all of the University of Pennsylvania.


The study recently was published on the website of the Journal of the American Statistical Association , a publication of the nation's oldest and largest organization of professional statisticians.


For the study, the research team accessed a Medicare database from several states covering a period of two years to create two matched groups of surgical patients. The data consisted of 130,106 patients who were operated on in 498 hospitals. The two groups created through the matching process consisted of 6,260 each and were similar in 2.9 million categories. For example, each group had the same number of patients who received each surgical procedure (i.e., knee replacement, appendectomy). Additionally, among patients who received a particular procedure, the numbers of patients who had a particular pre-existing condition (i.e., diabetes, past stroke, and ) also were as close as possible across the two groups. "Matching" patients in this way makes it easier to compare the clinical outcomes of the two groups.


Following its analysis of the data for each patient group, the researchers found that the mortality rate for patients of experienced surgeons was 3.59% (225 deaths out of 6,260 surgeries), while the mortality rate of new surgeons was 3.71% (232 deaths out of 6,260 surgeries).


"It is reassuring that new surgeons were able to achieve similar mortality rates to experienced surgeons when caring for similar patients. However, mortality is a relatively rare event that may not expose the benefits of experience," said Dr. Kelz. "Therefore, future studies focused on additional outcomes are needed to ensure that new surgeon training and transition to independent practice are appropriately structured to meet the surgical needs of the public."


Among the factors that require further analysis are the following:



  • First, because new surgeons trained under the shortened training model only recently have entered the nation's health care system, further analysis will determine if the findings will generalize to patient outcomes of experienced and new surgeons following the reduction in the training time.

  • Also, the research team compared outcomes across multiple surgical specialties to demonstrate the feasibility of the new statistical methodology. More patients are needed to examine clinically relevant subsets of patients and to examine additional important outcomes such as post-operative complications and health care costs.

  • Last, the pilot data used for the analysis was limited and thus narrows the generalizability of the study's findings. The researchers have applied for funding to run a broader analysis to see if the patient outcomes of new and experienced surgeons do, in fact, generalize.


"Mandates changing professional education often are implemented without a method to investigate the downstream effects on the population health. This new methodology can be used in a larger study to examine the important question of whether new and experienced surgeons achieve equivalent outcomes following the mandated changes in the training paradigm. Additionally, the methodological framework we establish can be used to monitor the effects of subsequent changes to the health care workforce on patient outcomes across a variety of practice settings and clinical conditions," wrote the researchers.


The new statistical methodology used in this study—called "large, sparse optimal matching"—was developed because patients typically are assigned to surgeons in a nonrandom manner. As a result, there may be systematic differences between the patients of recent surgical graduates and experienced surgeons, making measurement of surgeon effects difficult. For instance, within the pilot data, newly trained surgeons tended to operate on a different mix of patients than experienced surgeons. The patients of new surgeons more often were admitted via the emergency room and had higher risk factors on average. Other differences include the severity of a patient's illness and risk of mortality across patients.


In the study, the statistical matching method accounted for these discrepancies and allowed researchers to make fairer comparisons between similar groups of patients. Once the initial discrepancies were removed, researchers no longer observed any significant mortality difference between the two groups.


The new techniques developed for this study have tremendous promise to enable large-scale comparisons across a variety of settings and populations with appropriate control for differences in patient cohorts that was not previously possible.


"The new methodology will make it much easier to create good matches from large medical data sets," said Pimentel. "Large, sparse optimal matching will be useful in contexts outside of clinical medicine, too, including education research and public health, and I'm excited to see what other scientific questions it can help answer."




Provided by American Statistical Association



Medical Xpress on facebook

Related Stories


Surgical metrics do not provide a clear path to improvement, study says


Feb 03, 2015



While surgical outcomes have improved nationally over time, surgical outcome reporting does not necessarily lead to better outcomes, according to a Mayo Clinic study published this week in the Journal of the American Medical As ...



Practice makes perfect in cancer surgery


Nov 07, 2014



In a new, in-depth research project, Queen's professors Rob Siemens (Urology) and Christopher Booth (Cancer Care and Epidemiology) investigated what affect higher volume hospitals and surgeons had on the outcomes of patients ...



Surgery for pulmonary embolism may prevent


Feb 10, 2015



A surgical procedure that was virtually abandoned in the 1950s because of its high mortality rates in trying to save patients with acute pulmonary embolism may actually prevent more deaths in severely ill patients than current ...



New approach to colorectal surgical care results in quicker recovery times and lower costs


Feb 05, 2015



A new multidisciplinary approach to managing patients undergoing a colorectal operation results in shorter hospital stays, fewer complications, and lower medical costs, according to research results published online in the ...



Study examines link between surgical quality improvement program and outcomes, costs


Feb 03, 2015



Nicholas H. Osborne, M.D., M.S., of the University of Michigan, Ann Arbor, and colleagues evaluated the association of participation in the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) ...



Recommended for you


Lab tests and ultrasounds identify children who need surgical treatment for appendicitis


Feb 19, 2015



Data from two standard diagnostic tests commonly obtained in children evaluated for abdominal pain—when combined—can improve the ability of emergency department physicians and pediatric surgeons to identify those patients ...





Post-electrophysiology mortality usually not related to procedure


Feb 18, 2015



(HealthDay)—Half of major complications within 30 days of electrophysiology (EP) procedures occur after discharge, but the majority of deaths are not directly related to the procedure, according to a study ...



S. Korea cracks down on foreign-focused plastic surgery clinics


Feb 13, 2015



South Korea on Friday announced a crackdown on illegal brokers and unregistered clinics in a bid to protect medical tourists, especially those drawn by the country's booming plastic surgery industry.



Defensive neurosurgery up in states with high liability risk


Feb 12, 2015



(HealthDay)—Neurosurgeons are more likely to practice defensive medicine in states with high state-level liability risk, according to a study published in the February issue of Neurosurgery.





Number of hip replacements has skyrocketed, US report shows


Feb 12, 2015



(HealthDay)—The number of hip replacements performed in the United States has increased substantially, and the procedure has become more common in younger people, new government statistics show.





Post-op infection rate low for minimally invasive spine Sx


Feb 11, 2015



(HealthDay)—For patients undergoing posterior transtubular microscopic assisted spinal surgery, the postoperative infection rate is very low, according to a study published in the Feb. 1 issue of Spine.



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