• 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

  • Preface xi

    Acknowledgments xiii

    About the companion website xiv

    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 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

  • 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.

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