Surgical Arithmetic - Faculty of Medicine - McGill University

233 Pages·2003·1.58 MB·English

LANDES V a d e m e c u m LANDES LANDES V a d e m e c u m
BIOSCIENCE
BIOSCIENCE BIOSCIENCE
V
a
d
Table of contents Surgical
e
m
1. Epidemiologic Methods 8. An Introduction to Decision
e
for Surgery Analysis
c
u Arithmetic:
2. Introduction to Biostatistics: 9. Pharmacoeconomics
m
Describing and Drawing and Surgery
Inferences from Data
10. The Costing of Medical
3. Interpretation of Diagnostic
Resources Epidemiological, Statistical
Tests
and Outcome-Based Approach
11. Databases and Registries
4. Primer on Clinical Trials S
u to Surgical Practice
12. “Do-It-Yourself Outcomes”: rg
5. Linear and Logistic Using Outcomes in Clinical ic
Regression Analysis a
Practice to Assess l A
6. Survival Analysis and Improve Quality of Care rith
m
7. A Brief Introduction 13. Technology Assessment e
to Meta-Analysis tic
This is one of a new series of medical handbooks.
It includes subjects generally not covered in other handbook series, especially
many technology-driven topics that reflect the increasing influence of technology
in clinical medicine.
The name chosen for this comprehensive medical handbook series is Vademecum,
a Latin word that roughly means “to carry along”. In the Middle Ages, traveling
clerics carried pocket-sized books, excerpts of the carefully transcribed canons,
known as Vademecum. In the 19th century a medical publisher in Germany, Samuel
Karger, called a series of portable medical books Vademecum.
The Vademecum books are intended to be used both in the training of physicians
and the care of patients, by medical students, medical house staff and practicing
physicians. We hope you will find them a valuable resource.
R
BarkJoseosen Lawrence Rosenberg
All titles available at ISBN 1-57059-672-7 unphbe
rg Lawrence Joseph
www.landesbioscience.com
Alan Barkun
v a d e m e c u m
Surgical Arithmetic:
Epidemiological, Statistical and Outcome-Based
Approach to Surgical Practice
Lawrence Rosenberg, MD, PhD
McGill University
Montreal, Quebec, Canada
Lawrence Joseph, PhD
McGill University
Montreal, Quebec, Canada
Alan Barkun, MD, MSc
McGill University
Montreal, Quebec, Canada
L A N D E S
B I O S C I E N C E
GEORGETOWN, TEXAS
U.S.A.
VADEMECUM
Surgical Arithmetic:
Epidemiological, Statistical and Outcome-Based Approach to Surgical Practice
LANDES BIOSCIENCE
Georgetown, Texas U.S.A.
Copyright ©2000 Landes Bioscience
All rights reserved.
No part of this book may be reproduced or transmitted in any form or by any
means, electronic or mechanical, including photocopy, recording, or any
information storage and retrieval system, without permission in writing from the
publisher.
Printed in the U.S.A.
Please address all inquiries to the Publisher:
Landes Bioscience, 810 S. Church Street, Georgetown, Texas, U.S.A. 78626
Phone: [phone]; FAX: [phone]
ISBN: 1-57059-672-7
Library of Congress Cataloging-in-Publication Data
Surgical Arithmetic: Epidemiological, Statistical
and Outcome-Based Approach to Surgical Practice / [editors], Lawrence
Rosenberg, Lawrence Joseph, Alan Barkun.
p.;cm.--(Vademecum)
Includes bibliographical references and index.
ISBN 1-57059-672-7
1. Surgery--statistical methods. 2. Epidemiology--statistical methods.
I. Rosenberg, Lawrence, M.D. II. Joseph, Lawrence, Ph.D. III. Barkun,
Alan. IV. Title. V. Series.
[DNLM: 1. Statistics--methods. 2. Surgery. 3. Models, Statistical. WA
950 S961 2000]
RD29.7.S87 2000
617'005'195--dc21 00-057734
While the authors, editors, sponsor and publisher believe that drug selection and dosage and
the specifications and usage of equipment and devices, as set forth in this book, are in accord
with current recommendations and practice at the time of publication, they make no
warranty, expressed or implied, with respect to material described in this book. In view of the
ongoing research, equipment development, changes in governmental regulations and the
rapid accumulation of information relating to the biomedical sciences, the reader is urged to
carefully review and evaluate the information provided herein.
Dedication
To our students and colleagues
Contents
1. Epidemiologic Methods for Surgery .................................1
Jean-François Boivin and Alan Barkun
Descriptive Epidemiology...........................................................................1
Analytic Epidemiology................................................................................2
Cohort Studies............................................................................................3
Case-Control Studies..................................................................................4
Person-Time...............................................................................................5
Interpretation of Results.............................................................................7
Temporal Sequence.....................................................................................7
Precision.....................................................................................................8
Bias.............................................................................................................9
Confounding..............................................................................................9
Selection Bias............................................................................................11
Observation Bias.......................................................................................11
Conclusion...............................................................................................12
2. Introduction to Biostatistics: Describing and Drawing
Inferences from Data ......................................................14
Lawrence Joseph
1. Introduction.........................................................................................14
2. Descriptive Statistics.............................................................................15
3. Probability............................................................................................21
4. Drawing Statistical Inferences About a Population from a Sample.........32
5. Statistical Inference for Two or More Proportions.................................40
6. Statistical Inference for Means ..............................................................44
7. Nonparametric Inference......................................................................48
8. Sample Size Calculations.......................................................................51
9. Bayesian Inference ................................................................................53
Conclusions..............................................................................................62
3. Interpretation of Diagnostic Tests...................................64
Joseph Romagnuolo, Alan N. Barkun and Lawrence Joseph
Diagnostic Tests and the 2 x 2 Table .........................................................64
Sensitivity and Specificity vs Predictive Values...........................................65
Odds and Likelihood Ratios.....................................................................68
Bayes Theorem and Posttest Probabilities..................................................71
Choosing the Best Cutoff Value................................................................74
The Screening Test—Special Considerations.............................................78
Approach to a Study Examining a Diagnostic Test....................................80
Summary..................................................................................................81
4. Primer on Clinical Trials.................................................84
Robin S. McLeod
1. Determining the Question....................................................................85
2. Selection of Subjects.............................................................................86
3. Allocating Subjects................................................................................87
4. Describing the Maneuver......................................................................89
5. Measuring Outcome.............................................................................92
6. Analyzing the Data...............................................................................95
7. Estimating the Sample Size...................................................................98
8. Ethical Considerations..........................................................................99
9. Administrative Issues ..........................................................................100
Conclusions............................................................................................101
5. Linear and Logistic Regression Analysis .......................104
R. Platt
1. Introduction.......................................................................................104
2. Simple Linear Regression....................................................................105
3. Multiple Linear Regression.................................................................112
4. Logistic Regression..............................................................................116
5. Confounding and Causation...............................................................118
6. Effect Modification or Interaction ......................................................118
7. Conclusion and Literature Review......................................................120
6. Survival Analysis...........................................................122
David B. Wolfson and Cyr Emile M’Lan
1. Introduction.......................................................................................122
2. What Is Survival Analysis?...................................................................123
3. Censoring...........................................................................................123
4. Notation and Terminology..................................................................125
5. Nonparametric Methods.....................................................................126
6. The Comparison of Two Survival Distributions..................................129
7. Parametric Models..............................................................................131
8. Covariates...........................................................................................132
9. An Example of a Survival Analysis ......................................................135
Closing Remark......................................................................................141
7. A Brief Introduction to Meta-Analysis..........................143
Lawrence Joseph
1. Introduction—Why Consider Meta-Analysis?....................................143
2. What Is the Question, and Which Studies Should Be Included?.........144
3. Fixed Effects Meta-Analytic Methods..................................................147
4. Random Effects Meta-Analysis Models...............................................153
5. Summary of the Application...............................................................157
6. Conclusion.........................................................................................157
8. An Introduction to Decision Analysis...........................159
Alan Barkun, Neena Abraham and Lawrence Joseph
Clinical Judgement and the Science of Decision Making........................159
Introduction to the Basic Principles of Decision Making........................160
Incorporating Cost-Effectiveness in Your Decision Analysis....................168
The Final Analysis ..................................................................................169
9. Pharmacoeconomics and Surgery .................................171
Pierre MacNeil and Lawrence Rosenberg
Introduction...........................................................................................171
What Is Pharmacoeconomics?.................................................................171
Comparators and Perspective in a Pharmacoeconomics Analysis.............172
Costs and Consequences.........................................................................173
Different Types of Pharmacoeconomic Analysis......................................174
Cost-Minimization Analysis....................................................................174
Cost-Effectiveness Analysis.....................................................................175
Obtaining and Using Effectiveness Data.................................................177
Presentation of the Results......................................................................177
Cost-Utility Analysis...............................................................................178
How Is Utility Measured? .......................................................................179
Human Capital.......................................................................................180
Observed or Expressed Individual Preferences.........................................181
Other Issues Surrounding Pharmacoeconomics.......................................181
Conclusion.............................................................................................183
10. The Costing of Medical Resources................................186
Ralph Crott
Introduction...........................................................................................186
Costs or Charges?....................................................................................186
Defining the Medical Intervention..........................................................187
Defining the Study Viewpoint or Perspective..........................................187
Defining the Time Period of Cost Coverage............................................188
Defining Types of Costs..........................................................................189
Indirect Costs.........................................................................................190
Transfer Costs.........................................................................................191
Unrelated Future Costs...........................................................................191
Defining the Resource Items to Be Collected..........................................192
Collecting Data on Resources Used ........................................................192
Estimating Unit Costs of Resources........................................................193
Total, Average and Marginal Cost...........................................................194
Correcting for Time Preference...............................................................196
Correcting for Inflation ..........................................................................197
Micro-Costing versus Gross Costing.......................................................198
Conclusions............................................................................................198
11. Databases and Registries...............................................200
J. Sampalis
Overview................................................................................................200
1. Defining the Purpose..........................................................................200
2. Identifying the Patient Population ......................................................201
3. Determining the Variable Set..............................................................202
4. Direction and Follow-Up....................................................................204
5. The Data Collection Process...............................................................204
6. Data Management..............................................................................206
7. Record Linkage...................................................................................208
8. Statistical Uses of Registries.................................................................209
Conclusion.............................................................................................210
12. “Do-it-yourself Outcomes”: Using Outcomes in Clinical
Practice to Assess and Improve Quality of Care............212
Liane Feldman and Jeffrey Barkun
Evolution of the Outcomes Movement...................................................212
Quality and Outcomes of Care: Definitions............................................214
Continuous Quality Improvement (CQI): Using Outcomes
to Improve Quality.................................................................................216
Limitations of Outcome Evaluation........................................................218
“Do It Yourself Outcomes” in Everyday Practice.....................................220
Example: Pilot Project of Outcomes Assessment.....................................221
Conclusions............................................................................................225
13. Technology Assessment.................................................230
Jeffrey Barkun and Alan Barkun
Introduction...........................................................................................230
The Need for Technology Assessment.....................................................231
Models of Technology Assessment...........................................................231
The Types of Technologies to Be Assessed...............................................232
The Development of a Technology–The Life Cycle
of Technology Assessment.......................................................................233
The Timing of Technology Assessment...................................................235
Diffusion of Study Results......................................................................236
Special Issues in Health Technology Assessment......................................237
The Status of Health Technology Assessment Worldwide........................238
Ethical Issues in Technology Assessment.................................................238
Conclusion.............................................................................................239
Index.............................................................................243
Editors
Lawrence Rosenberg, MD, PhD
Division of Surgical Research
Department of Surgery
McGill University
Montreal, Quebec, Canada
Chapter 9
Lawrence Joseph, PhD
Division of Clinical Epidemiology
Montreal General Hospital
Department of Epidemiology and Biostatistics
McGill University
Montreal, Quebec, Canada
Chapters 2, 3, 7, 8
Alan Barkun, MD, MSc
Division of Gastroenterology
Department of Epidemiology and Biostatistics
McGill University
Montreal, Quebec, Canada
Chapters 1, 3, 8, 12, 13
Contributors
Neena Abraham Ralph Crott
Division of Gastroenterology Pharmacoeconomics
McGill University Health Centre Faculty of Pharmacy
Montreal, Quebec, Canada University of Montreal
Chapter 8 Montreal, Quebec, Canada
Chapter 10
Jeffrey Barkun
Divisions of General Surgery, Liane Feldman
Epidemiology and Biostatistics Department of General Surgery
McGill University Health Centre Montreal General Hospital
Montreal, Quebec, Canada McGill University
Chapter 13 Montreal, Quebec, Canada
Chapter 12
Jean-François Boivin
Centre for Clinical Epidemiology Pierre MacNeil
and Community Studies Special Products
Sir Mortimer B. Davis Jewish Merck Frosst Canada and Co.
General Hospital Montreal, Quebec, Canada
Department of Epidemiology Chapter 9
and Biostatistics
McGill University Cyr Emile M’Lan
Montreal, Quebec, Canada Department of Mathematics and Statistics
Chapter 1 McGill University
Montreal, Quebec, Canada
Chapter 6
Robin S. McLeod Joseph Romagnuolo
Division of General Surgery Division of Gastroenterology
Mount Sinai Hospital McGill University
Departments of Surgery Montreal, Quebec, Canada
and Public Health Sciences Chapter 3
University of Toronto
Toronto, Ontario, Canada J. Sampalis
Chapter 4 Division of Clinical Epidemiology
Montreal General Hospital
R. Platt Montreal, Quebec, Canada
Montreal Children's Hospital Chapter 11
Research Institute
Department of Epidemiology David B. Wolfson
and Biostatistics Department of Mathematics
McGill University and Statistics
Montreal, Quebec, Canada McGill University
Chapter 5 Montreal, Quebec, Canada
Chapter 6