Author Interviews, Surgical Research / 21.05.2016
ACS Surgical Risk Calculator Reliably Guides Decision Making
MedicalResearch.com Interview with:
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Dr. Mark Cohen[/caption]
Mark E. Cohen, PhD
Statistical Manager
Continuous Quality Improvement
Division of Research and Optimal Patient Care
American College of Surgeons
Chicago, IL
MedicalResearch.com: What is the background for this study?
Dr. Cohen: The ACS NSQIP Surgical Risk Calculator (built from 2.7 million patient records from nearly 600 hospitals) has been widely adopted as a decision aid and informed consent tool by surgeons and patients. Predictive accuracy can be assessed in terms of discrimination, calibration, and combined discrimination and calibration. In this study, we focused primarily on calibration. Calibration refers to the consistency of agreement between observed and predicted risk across the range of predicted risk. One would not want, for example, a model that dramatically overestimates risk for low-risk patients and underestimates risk for high-risk patients – this sort of systematic error, if of sufficient magnitude, would make a risk calculator unacceptable for clinical use. We also assessed the potential benefits of statistical recalibration using restricted cubic splines.
MedicalResearch.com: What are the main findings?
Dr. Cohen: Without recalibration, the Risk Calculator was shown to have excellent calibration, though there was, at times, a slight tendency for predicted risk to be overestimated for lowest- and highest-risk patients and underestimated for moderate-risk patients. After recalibration this distortion was eliminated.
Dr. Mark Cohen[/caption]
Mark E. Cohen, PhD
Statistical Manager
Continuous Quality Improvement
Division of Research and Optimal Patient Care
American College of Surgeons
Chicago, IL
MedicalResearch.com: What is the background for this study?
Dr. Cohen: The ACS NSQIP Surgical Risk Calculator (built from 2.7 million patient records from nearly 600 hospitals) has been widely adopted as a decision aid and informed consent tool by surgeons and patients. Predictive accuracy can be assessed in terms of discrimination, calibration, and combined discrimination and calibration. In this study, we focused primarily on calibration. Calibration refers to the consistency of agreement between observed and predicted risk across the range of predicted risk. One would not want, for example, a model that dramatically overestimates risk for low-risk patients and underestimates risk for high-risk patients – this sort of systematic error, if of sufficient magnitude, would make a risk calculator unacceptable for clinical use. We also assessed the potential benefits of statistical recalibration using restricted cubic splines.
MedicalResearch.com: What are the main findings?
Dr. Cohen: Without recalibration, the Risk Calculator was shown to have excellent calibration, though there was, at times, a slight tendency for predicted risk to be overestimated for lowest- and highest-risk patients and underestimated for moderate-risk patients. After recalibration this distortion was eliminated.
Dr. Atul Sharma[/caption]
Atul Sharma MD, MSc(Statistics), FRCPC
Researcher, Children’s Hospital Research Institute of Manitoba; Assistant Professor, Department of Pediatrics and Child Health, University of Manitoba; Senior Consultant, Biostatistics Group, George and Fay Yee Center for Healthcare Innovation
MedicalResearch.com: What is the background for this study? What are the main findings?
Dr. Sharma: Between 1978 and 2004, a previous comparison of directly measured heights and weights demonstrated an alarming increase in the prevalence of overweight or obesity in Canadian children aged 2-17y, from 23.3% (95% CI = 20.5-26.0) to 34.7% (33.0-36.4) based on the new 2007 WHO criteria.
In Canada, the definitions of overweight and obesity changed with the introduction of the new '2010 WHO Growth Charts for Canada’, Previous definitions were based on Body Mass Index (BMI) percentiles from the 2000 Centers for Disease Control and Prevention (CDC) growth chart’s. In addition to revising the percentile thresholds for diagnosing overweight or obesity, the WHO charts were based on a very different reference population. As a result, the proportion of Canadian children being classified as overweight or obese increased with the introduction of the new WHO charts.
Our current study applied current Canadian definitions of overweight and obesity to a contemporary sample of Canadian children age 3-19y to assess recent trends in the rates of overweight and obesity. By pooling data from the Canadian Community Health Survey (CCHS, cycle 2.2) and the Canadian Health Measures Survey (CHMS, cycles 2 and 3), we were able to study a representative sample of more than 14000 Canadian children from the period 2004-2013. The sample was evenly split between boys and girls and approximately 80% white.
Dr. Josefin Segelman[/caption]
Josefin Segelman MD, PhD
Senior consultant colorectal surgeon
Department of Molecular Medicine and Surgery
Karolinska Institutet
Ersta Hospital
Stockholm Sweden
MedicalResearch.com: What is the background for this study?
Dr. Segelman: Hormonal factors influence the development of colorectal cancer. Observational studies and clinical trials have reported a protective effect of hormone replacement therapy and oral contraceptives. Oophorectomy alters endogenous levels of sex hormones, but the effect on colorectal cancer risk is unclear. Removal of the ovaries alters levels of sex hormones in both pre- and postmenopausal women. In premenopausal women, bilateral oophorectomy is followed by surgical menopause as the endogenous estrogen levels drop. Both before and after natural menopause, bilateral oophorectomy promptly decreases endogenous androgen levels by half as the ovaries and adrenals are equally important for androgen production.
MedicalResearch.com: What are the main findings?
Dr. Segelman: The present nationwide cohort study explored the association between removal of the ovaries for benign indications and subsequent risk of colorectal cancer. Among 195 973 women who underwent the procedure from 1965 – 2011, there was a 30% increased risk of colorectal cancer compared with the general population. After adjustment for various factors, women who underwent bilateral oophorectomy had a higher risk of rectal cancer than those who had unilateral oophorectomy (HR 2.28, 95% CI 1.33-3.91).
Dr. Alison Fecher[/caption]
Alison M. Fecher, MD
Assistant Professor of Surgery
Indiana University Health
MedicalResearch.com: What is the background for this study? What are the main findings?
Dr. Fecher: It has long been known that female faculty are underrepresented in departments of surgery at U.S. medical schools. Our study wanted to identify obstacles women face in entering certain surgical subspecialties and in career advancement. We found that women are poorly represented in some of the most competitive subspecialties, including cardiothoracic and transplant surgery. We also found that women tend to advance more slowly up the career ladder, with many of them spending more years at the assistant professor level than their male counterparts. One reason for this may be that they tend to publish less peer-reviewed articles than male faculty; however, our results show that the publications of female faculty often has a greater impact on the field, as measured by citations and recentness of articles.

Dr. Asal Mohamadi Johnson[/caption]
Asal Mohamadi Johnson, PhD, MPH
Assistant Professor of Epidemiology, Integrative Health Science
Stetson University
DeLand, FL 32723
MedicalResearch.com: What is the background for this study?
Dr. Johnson: Public health research is primarily focused on neighborhood poverty and racial disparities by illustrating differences between white and black individuals or communities. For example, it has been established that African Americans have higher cancer mortality rates and are less likely to receive appropriate treatment that whites. What we wanted to know in this study was the impact of living in segregated areas apart from other area level characteristics such as poverty or education. Instead of solely looking at health disparities between whites and black patients, our study focused on differences in survival among black patients with early stage Non-Small Cell Lung Cancer (NSCLC) living in different levels of neighborhood segregation.















Dr. Grace Wang[/caption]
MedicalResearch.com Interview with:
Dr. Grace Wang MD FACS
Assistant Professor of Surgery
Division of Vascular and Endovascular Surgery
Hospital of the University of Pennsylvania
Medical Research: What is the background for this study?
Dr. Wang: PAD is a major source of morbidity and mortality resulting in functional impairment, limb loss, as well as death. Despite epidemiologic studies which have contributed to our understanding of PAD prevalence and its association with traditional atherosclerotic risk factors, there have been conflicting studies published on the incidence of PAD and differences in treatment outcomes in women versus men. Patients with chronic kidney disease (CKD) are at particularly high risk for 

