Diagnostic Tests Toolkit E-Book

Matthew Thompson

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Serie: EBMT-EBM Toolkit Series
• Sprache: Englisch

Seitenzahl: 135

Veröffentlichungsjahr: 2011

Beschreibung

Diagnostic Tests Toolkit

Diagnostic Tests Toolkit

Finding the evidence for diagnostic tests

Establishing an evidence-based methodology to assess the effectiveness of diagnostic tests has posed problems for many years. Now that the framework is in place health professionals can find and appraise the evidence for themselves. With Diagnostic Tests Toolkit clinicians and junior researchers can interpret the evidence for the effectiveness of different types of diagnostic tests, or develop their own research using the successful ‘step-by-step’ format of the Toolkit series. Written by renowned clinical researchers, this is the first basic guide to evidence-based diagnosis. It is equally valuable to starters in clinical research and those needing a quick refresher on the core elements of evidence-based diagnosis.

Leseprobe

Table of Contents

Cover

Title page

Copyright page

Acknowledgements

Introduction

Definition of evidence-based medicine

CHAPTER 1 Diagnosis in evidence-based medicine

Diagnosis and screening

Screening

Symptoms

Signs and elicited symptoms

Bedside or point-of-care testing

Laboratory tests

Basic structure of studies of diagnostic tests

CHAPTER 2 Evaluating new diagnostic tests

Technical accuracy (‘Can it work?’)

Place in the clinical pathway (‘Where does the test fit in the existing clinical pathway?’)

Ability of the test to diagnose or exclude the target condition (‘Does it work in patients?’)

The effect of the test on patient outcomes (‘Are patients better off?’)

Cost-effectiveness (‘Is it worth the cost?’)

CHAPTER 3 Asking an answerable clinical question

Defining a clinical question for diagnostic tests – PIRT

CHAPTER 4 Finding the evidence: how to get the most from your searching

Combine textwords and thesaurus

Search filters for diagnostic accuracy studies

CHAPTER 5 Selecting relevant studies

Selecting relevant studies

Assessing validity

What is the difference between bias and variability in diagnostic studies?

The ‘ideal’ diagnostic study

Flow charts of patients

CHAPTER 6 Sources of bias in diagnostic studies

Spectrum bias (also known as selection bias)

Verification bias (also called referral or work-up bias)

Incorporation bias

Observer (or test review bias) bias

Differential reference bias (double gold standard)

What are the effects of the different design-related biases?

CHAPTER 7 Measures of discrimination of diagnostic tests

Two by two tables

Outcome measures

Which measure should you use and why?

The effect of prevalence on predictive values

Effect of time on diagnostic accuracy

Effect of severity of the target condition on diagnostic accuracy

The referral filter

Rules of thumb for interpreting likelihood ratios

CHAPTER 8 Using diagnostic information in clinical practice

Validity of data

Problem-solving strategies that clinicians use in diagnosis

Action thresholds versus testing thresholds (‘Will the test change my management?’)

Methods for combining test results

Multivariable analyses

How are clinical prediction rules developed?

How to select a prediction rule for clinical practice

CHAPTER 9 Screening tests

What are screening tests?

Different types of screening

Ideal study design for screening tests

Over-diagnosis

CHAPTER 10 Systematic reviews of diagnostic test accuracy studies

The research question

The literature search

Assess the quality of individual studies included in the review

Summarizing the results of diagnostic studies

Combining data and interpreting meta-analyses of diagnostic studies

Acknowledgements

APPENDIX 1  Evidence-based medicine – a glossary of terms

APPENDIX 2  Further reading

Index

STARD Checklist

This edition first published 2012, © 2012 by John Wiley & Sons Ltd

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A catalogue record for this book is available from the British Library.

Library of Congress Cataloging-in-Publication Data

Thompson, Matthew J.

 Diagnostic tests toolkit / Matthew Thompson, Ann Van den Bruel.

p. ; cm. – (EBM toolkit series)

 Includes bibliographical references and index.

 ISBN-13: 978-0-470-65758-4 (pbk. : alk. paper)

 ISBN-10: 0-470-65758-8 (pbk. : alk. paper)

 1. Diagnosis–Handbooks, manuals, etc. 2. Function tests

(Medicine)–Handbooks, manuals, etc. I. Van den Bruel, Ann. II. Title. III. Series: EBM toolkit series.

 [DNLM: 1. Diagnostic Techniques and Procedures–Handbooks. 2. Evidence-Based Medicine–Handbooks. WB 39]

 RC71.T56 2011

 616.07′5–dc23

2011020600

This book is published in the following electronic formats: ePDF 9781119951797; Wiley Online Library 9781119951827; ePub 9781119951803; mobi 9781119951810

Acknowledgements

This handbook was compiled by Matthew Thompson and Ann Van den Bruel based on teaching materials and workshops that we and other members of the Centre for Evidence-based Medicine have fine-tuned over a number of years for diagnostic tests. We particularly appreciate the input of the Toolkit Series Editors Carl Heneghan, Rafael Perera and Doug Badenoch. MT and AvdB thank their families for support in writing this book.

Introduction

This ‘Toolkit’ is designed as a summary and reminder of the key elements of practising evidence-based medicine (EBM), focusing on diagnostic studies and research questions. It has largely been adapted from resources developed at the Centre for Evidence-based Medicine. For more detailed coverage, you should refer to the further reading and references that we cite throughout.

The first page of each chapter presents a ‘minimalist’ checklist of the key points. Further sections within each chapter address these points in more detail and give additional background information. Ideally, you should just need to refer to the first page to get the basics, and delve into the further sections as required.

Definition of Evidence-Based Medicine

Evidence-based medicine is the ‘conscientious, explicit and judicious use of current best evidence in making decisions about individual patients’.

This means ‘integrating individual clinical expertise with the best available external clinical evidence from systematic research and the patient’s values and preferences’ (Sackett et al. 1996).

We can summarize the EBM approach as a five-step model:

1. Asking answerable clinical questions.

2. Searching for the evidence.

3. Critically appraising the evidence for its validity and relevance.

4. Making a decision, by integrating the evidence with your clinical expertise and the patient’s values.

5. Evaluating your performance.

Reference

Sackett DL, Rosenberg WMC, Gray JAM, et al. Evidence based medicine: what it is and what it isn’t. BMJ 1996;312:71–2.