PRACTICAL CLINICAL EPIDEMIOLOGY FOR THE VETERINARIAN

Preface
Acknowledgments
About the companion website
1 Describing health and disease 1
Case definition 1
What is the problem? 2
Who is affected? 4
Where is the disease concentrated? 5
When does disease occur? 5
Types of measurements 5
Counts 5
Proportions 7
Ratios 8
Rates 9
Specific measurements of disease 10
Prevalence 10
Incidence 13
Morbidity 16
Mortality 16
Disease ]specific mortality 16
Case ]fatality 17
2 Basic epidemiology concepts 19
Outcome 19
Risk factor 21
Unit of analysis 22
Types of variables 26
Appropriate statistical analyses for continuous/parametric variables 27
Appropriate statistical analyses for categorical/nonparametric variables 29
Appropriate statistical analyses for multiple samples taken from the same animal 30
Control groups 33
Sample size and P ]value 34
Error and bias 35
Confounding 41
Interaction 42
3 Evidence ]based medicine for the veterinarian 44
Evaluation of a research paper 49
Data presentation in the results 53
Interpretation of results 57
Statistical significance 58
Biological significance 60
4 Study designs 62
Retrospective studies 63
Case–control studies 64
Surveys 65
Cross ]sectional studies 68
Prospective studies 70
Cohort studies 70
Clinical trials 72
Sampling strategies 73
5 Causation versus association 77
Hill’s criteria to determine causation 78
Temporal association 78
Consistency of association 79
Specificity of association 79
Dose–response (biological gradient) 80
Biologic plausibility 81
Analogy 81
Measures of association 82
Odds ratio 84
Relative risk 89
Attributable risk 92
6 Diagnostic tests 94
Test quality 95
Accuracy 95
Precision 95
Discrimination ability 98
Test performance 99
Sensitivity 100
Specificity 102
Positive predictive value 104
Negative predictive value 105
Screening 107
Parallel testing 107
Serial testing 107
Gold standard 108
7 Outbreak investigations 109
Definitions 109
Steps in an outbreak investigation 110
Case definition/diagnosis verification 110
Determine the magnitude of the problem 111
Describe the spatial and temporal patterns of disease 112
Analyze potential risk factors 116
Follow ]up 119
Glossary 120
Formulas 125
Final word 128
References 129
Index 134

Practical Clinical Epidemiology for the Veterinarian provides thorough coverage of the fundamentals of epidemiological concepts, situated within the context of daily clinical practice.
- Examines epidemiology from the lens of daily clinical practice to offer a truly practical approach
- Demonstrates the relevance of epidemiology to clinical problems faced in the field using practical examples to clarify the concepts
- Includes clinical cases from all species, with an emphasis on small animal and equine medicine, to demonstrate the concepts
- Uses an easy-to-read approach, with graphs, flowcharts, and tables to promote understanding
- Includes access to a companion website with exercises for study and review

Author
Aurora Villarroel, DVM, MVPM, PhD, DACVPM, served as Assistant Professor of Clinical Sciences at the College of Veterinary Medicine and Extension Veterinarian in the Department of Animal Sciences at Oregon State University in Corvallis, Oregon. She taught epidemiology for 12 years at the veterinary schools of UC Davis, Colorado State University, and Oregon State University, and is currently a consultant at Athyr Vet, LLC.