Table Of ContentHot Topics in Acute Care Sugery and Trauma
Marco Ceresoli · Fikri M. Abu-Zidan
Kristan L. Staudenmayer · Fausto Catena
Federico Coccolini Editors
Statistics and
Research Methods
for Acute Care and
General Surgeons
Hot Topics in Acute Care Surgery
and Trauma
Series Editors
Federico Coccolini, General, Emergency and Trauma Surgery Department,
Pisa University Hospital, Pisa, Pisa, Italy
Raul Coimbra, Riverside University Health System Medical Center
Riverside, USA
Andrew W. Kirkpatrick, Department of Surgery and Critical Care Medic
Foothills Medical Centre Department of Surgery and Critical Care Medic
Calgary, AB, Canada
Salomone Di Saverio, Department of Surgery, Madonna Del Soccorso Hospital
San Benedetto del Tronto, Italy
Editorial Board
Luca Ansaloni, Dept. of Emergency and Trauma Surgery
Bufalini Hospital, Cesena, Italy
Zsolt Balogh, Newcastle, Australia
Walt, Biffl, Denver, USA
Fausto Catena, General and Emergency Surgery Dept, Ospedale “M. Bufalini”
di Cesena, Cesena, Italy
Kimberly Davis, New Haven, USA
Paula Ferrada, Richmond, USA
Gustavo Fraga, Campinas, Brazil
Rao Ivatury, Richmond, USA
Yoram Kluger, Haifa, Israel
Ari Leppaniemi, Helsinki, Finland
Ron Maier, Seattle, USA
Ernest E. Moore, Fort Collins, USA
Lena Napolitano, Ann Arbor, USA
Andrew Peitzman, Pittsburgh, USA
Patrick Reilly, Philadelphia, USA
Sandro Rizoli, Toronto, Canada
Boris E. Sakakushev, Plovdiv, Bulgaria
Massimo Sartelli, Macerata, Italy
Thomas Scalea, Baltimore, USA
David Spain, Stanford, USA
Philip Stahel, Denver, USA
Michael Sugrue, Letterkenny, Ireland
George Velmahos, Boston, USA
Dieter Weber, Perth, Australia
This series covers the most debated issues in acute care and trauma surgery, from
perioperative management to organizational and health policy issues. Since 2011,
the founder members of the World Society of Emergency Surgery’s (WSES) Acute
Care and Trauma Surgeons group, who endorse the series, realized the need to
provide more educational tools for young surgeons in training and for general
physicians and other specialists new to this discipline: WSES is currently developing
a systematic scientific and educational program founded on evidence-based
medicine and objective experience. Covering the complex management of acute
trauma and non-trauma surgical patients, this series makes a significant contribution
to this program and is a valuable resource for both trainees and practitioners in acute
care surgery.
Marco Ceresoli • Fikri M. Abu-Zidan
Kristan L. Staudenmayer • Fausto Catena
Federico Coccolini
Editors
Statistics and Research
Methods for Acute Care
and General Surgeons
Editors
Marco Ceresoli Fikri M. Abu-Zidan
General and Emergency Surgery Department of Surgery, College of
Department, School of Medicine and Medicine and Health Science
Surgery, Milano-Bicocca University United Arab Emirates University
Monza, Italy Abu Dhabi, United Arab Emirates
Kristan L. Staudenmayer Fausto Catena
Department of Surgery, Stanford University General and Emergency Surgery
Stanford, CA, USA Department Bufalini Hospital
Cesena, Italy
Federico Coccolini
Department of General, Emergency and
Trauma Surgery, Pisa University Hospital
Pisa, Pisa, Italy
ISSN 2520-8284 ISSN 2520-8292 (electronic)
Hot Topics in Acute Care Surgery and Trauma
ISBN 978-3-031-13817-1 ISBN 978-3-031-13818-8 (eBook)
https://doi.org/10.1007/978-3-031-13818-8
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Preface: Why a Statistics Manual in the Series
of “Hot Topics in Acute Care Surgery”?
In the last decades we have experienced major medical and surgical advancements.
The transition from “eminence-based medicine” to “evidence-based medicine” is
one of the most important pillars of modern medicine. Fortunately, it is now
extremely rare to hear odious terms reflecting personal opinions like “we have
always done it that way” or “my mentor taught me that…”. and it is now recognized
that clinical decisions should be made according to the evidence.
The ability to read and properly understand scientific research articles is vital to
employ an evidence-based medicine approach. How many times we have blindly
trusted the results of a paper without critically evaluating it? We find ourselves sur-
prised later on to find that these results were flawed or wrongly interpreted. The
modern healthcare professionals, including acute care surgeons, must have the
essential skills to practice evidence-based medicine which includes the ability to
design a research project and perform statistical analyses.
In the famous Italian novel the Adventures of Pinocchio by C. Collodi, the
wooden marionette Pinocchio meets two shady characters, the fox and the cat, who
try to cheat him by taking advantage of his trust. We think that this is similar to a
young surgeon who reads a paper trusting its reported p-values without understand-
ing, interpreting, and critically appraising what was reported.
v
vi Preface: Why a Statistics Manual in the Series of “Hot Topics in Acute Care Surgery”?
We therefore have decided to write this concise manual with the goal of helping
to strengthen the acute care surgeon’s statistical knowledge and to provide the nec-
essary support to face the complexity of evidence-based medicine.
Some acute care surgeons may attempt to use a classical statistical book to inter-
pret and analyze the data from their studies. They might get discouraged when they
encounter statistical concepts expressed as complex mathematical formulas. This
makes the surgeon entirely dependent on a statistician who may not have the same
clinical understanding or the context for the clinical problem.
We have designed this manual to be an easy-to-use reference for acute care sur-
geons. It has been written by surgeons for surgeons with straightforward explana-
tions and examples, without math. It is meant to improve a surgeon’s basic
understanding of applied statistics, rather than a deep dive into theoretical statistics.
By doing so, we hope to make statistics more accessible and expect that readers will
find that fundamental statistical principles can be easy to understand.
Preface: Why a Statistics Manual in the Series of “Hot Topics in Acute Care Surgery”? vii
The present manual has three parts. The first covers scientific methods as applied
to medical research. The second covers basic statistics. The third covers commonly
used advanced statistical methods such as multivariate analysis, meta-analysis, and
survival analysis. These chapters will provide practical examples in order to provide
context and to ease readers into statistical science.
Monza, Italy Marco Ceresoli
Abu Dhabi, United Arab Emirates Fikri M. Abu-Zidan
Stanford, CA, USA Kristan L. Staudenmayer
Cesena, Italy Fausto Catena
Pisa, Italy Federico Coccolini
Contents
Part I Designing Your Research
1 Study Typology: An Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Giacomo Mulinacci and Marco Carbone
2 Diagnostic Studies Made Easy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Fikri M. Abu-Zidan, Marco Ceresoli, and Saleh Abdel-Kader
3 Common Pitfalls in Research Design and Its Reporting . . . . . . . . . . . . 29
Fikri M. Abu-Zidan
Part II Basic Statistical Analysis
4 Introduction to Statistical Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Luca Gianotti
5 Analyzing Continuous Variables: Descriptive Statistics,
Dispersion and Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Marco Ceresoli and Luca Nespoli
6 Analyzing Categorical Variable: Descriptive Statistics
and Comparisons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Alessandro Cucchetti
Part III Advanced Statistics
7 Multivariate Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Niccolò Allievi and Marco Ceresoli
8 Survival Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Simone Famularo and Davide Bernasconi
9 Meta-Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Marco Ceresoli, Fikri M. Abu-Zidan, and Federico Coccolini
10 Randomized Trials and Case–Control Matching Techniques . . . . . . . . 125
Emanuele Russo, Annalaura Montalti,
Domenico Pietro Santonastaso, and Giuliano Bolondi
ix
x Contents
11 Difference-In-Difference Techniques and Causal Inference . . . . . . . . . 139
Sue Fu, Katherine Arnow, Amber Trickey, and Lisa Marie Knowlton
12 Machine Learning Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Jeff Choi, Nima Aghaeepour, and Martin Becker
13 Statistical Editor’s Practical Advice for Data Analysis . . . . . . . . . . . . . 165
Fikri M. Abu-Zidan
