i Assessing the Cost-effectiveness of Alternative Measures Aimed at Reducing the Prevalence of ...

240 Pages·2011·2.58 MB·English

by  Claudia Schmidt

Assessing the Cost-effectiveness of Alternative Measures Aimed at Reducing the
Prevalence of Foodborne Microbiological Hazards

A Thesis
Presented to
The Faculty of Graduate Studies
of
The University of Guelph

By
CLAUDIA SCHMIDT

In partial fulfilment of requirements
For the degree of
Doctor of Philosophy
September 2011

© Claudia Schmidt, 2011
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ABSTRACT

ASSESSING THE COST-EFFECTIVENESS OF ALTERNATIVE
MEASURES AIMED AT REDUCING THE PREVALENCE OF FOOD-
BORNE MICROBIOLOGICAL HAZARDS

Claudia Schmidt Advisors:
University of Guelph, 2011 Spencer Henson and John Cranfield

Foodborne illnesses place a burden on the entire society. One strategy to lower the costs
of foodborne illnesses is to reduce the prevalence of foodborne pathogens through
interventions along the food supply chain. There is an ongoing trend that food safety
systems are moving towards performance-based regimes, which rely on the
implementation of food safety standards. However, the implementation of food safety
standards has not garnered much interest in the Canadian policy environment. The
assessment of food safety interventions to achieve a standard is challenging as the
underlying biological processes are complex, the costs of administering such
interventions are not abundantly clear and the set of available interventions is changing.
This thesis investigates the cost-effectiveness of food safety interventions and
specifically the applicability of a food safety standard. First, a theoretical model is
developed to investigate how; in theory cost-minimization can be used to identify the
most cost-effective way to reduce foodborne pathogens with the utilization of a food
safety standard. Then, a specific framework is developed for Campylobacter in chicken
that consists of interrelated simulation models that represent the level and flow of
pathogens through a commodity supply chain, the impact of alternative interventions on
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pathogen load and their costs. The case study focus is Ontario, Canada. Different
interventions are compared and evaluated based on their compliance with a food safety
standard. The applicability of different cost-effectiveness measures is assessed.

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Acknowledgements

I gratefully acknowledge the support of my co-advisors Prof. John Cranfield and Prof.
Spencer Henson. They have encouraged my interest in this field far beyond this thesis. I
highly appreciate their support and enthusiasm.
I would like to thank my other committee members Prof. Julie Caswell, Aamir Fazil and
Prof. Alfons Weersink for their helpful advice and comments. I would also like to thank
Dr. Juliana Ruzante and Prof. Shai Barbut for their advice. I would like to extend my
sincere appreciation to Dr. Sandra Hoffmann for being the external examiner.

I would also like to thank the staff at the George Morris Centre for giving me the
opportunity to gain work experience while completing my thesis research.

Finally, I would like to thank my family, especially my fiancé Arian Khaleghi
Moghadam, for being incredibly supportive. I would also like to thank my friends for
their support, particularly Kate Tsiplova, Maria Klimas, Julia Witt, Burç Kayahan, Eva
Küttner, Susan Robertson, Kathleen Rodenburg, Rodney Gill and Johanna Görtz.

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Table of Contents

1 Introduction .................................................................................................................... 1
1.1 Food Safety in a Canadian Context .............................................................................. 1
1.2 Economic Problem ........................................................................................................ 4
1.3 Economic Research Problem ........................................................................................ 5
1.4 Purpose and Objectives ................................................................................................. 8
1.5 Benefits of Research ..................................................................................................... 9
1.6 Organisation of the Thesis .......................................................................................... 10
2 The Food Safety Problem and Methods used to Analyse the Costs and Benefits of
Food Safety Interventions .............................................................................................. 11
2.1 Demand, Supply and the Optimal Level of Food Safety ............................................ 11
2.2 Provision of Safe Food – Market vs. Government ..................................................... 14
2.3 Microbiological Criteria to Ensure Safe Food ............................................................ 16
2.4 HACCP vs. Microbiological Standards ...................................................................... 17
2.5 Food Risk Analysis ..................................................................................................... 21
2.6 Economic Evaluations of Food Safety Interventions and Food Borne Diseases ........ 23
2.6.1 Cost Analysis - Estimating the Costs of Food Safety Interventions ..................... 24
2.6.2 Cost Minimization Analysis ................................................................................. 25
2.6.3 Cost Benefit Analysis ........................................................................................... 26
2.6.4 Cost-effectiveness Analysis .................................................................................. 29
2.6.5 Cost-Utility Analysis ............................................................................................ 30
2.6.6 Risk-Risk and Health-Health Analysis ................................................................. 31
2.6.7 Value at Risk ......................................................................................................... 32
2.6.8 Expert Opinion Assessment .................................................................................. 33
2.6.9 Summary ............................................................................................................... 34
2.7 Risk and Uncertainty in the Economic Analysis of Food Safety ................................ 35
2.7.1 Risk versus Uncertainty ........................................................................................ 35
2.7.2 Dealing with Risk and Uncertainty ....................................................................... 38
2.7.3 Combination of Economic and Microbiological Risk Modeling .......................... 40
2.8 Food-risk Prioritization and Management .................................................................. 42
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2.9 Conclusion .................................................................................................................. 43
3 A Cost Minimization Approach to Comply with Food Safety Standards .............. 46
3.1 Introduction ................................................................................................................. 46
3.2 Economic Model ......................................................................................................... 47
3.3 Deterministic Model ................................................................................................... 49
3.3.1 Supply Chain with Two Stages ............................................................................. 49
3.4 Stochastic Model - Introducing Uncertainty ............................................................... 58
3.5 Practical Application ................................................................................................... 63
3.5.1 Adoption of interventions ..................................................................................... 64
3.6 Summary ..................................................................................................................... 66
4 Modeling Approach and Data: Reducing Campylobacter in Chicken. ................... 67
4.1 Introduction ................................................................................................................. 67
4.1.1 Analytical Framework .......................................................................................... 68
4.2 Campylobacter in Chicken as a Specific Case Study ................................................. 70
4.2.1 Campylobacter ...................................................................................................... 70
4.3 Microbiological Model ............................................................................................... 74
4.3.1 Risk Assessment Models of Campylobacter in Chicken ...................................... 74
4.3.2 Quantitative Risk Assessment Model ................................................................... 75
4.4 Food Safety Interventions to Reduce Campylobacter along the Chicken Supply Chain
81
4.4.1 Data ....................................................................................................................... 81
4.4.2 Chicken Production and Consumption in Ontario ................................................ 82
4.4.3 Interventions along the Chicken Supply Chain – Efficacy ................................... 85
4.4.4 Interventions along the Chicken Supply Chain –Cost Assessment ...................... 99
4.5 The Public Health Impact of Campylobacteriosis on the Ontario Population .......... 111
4.5.1 General Assumptions .......................................................................................... 112
4.5.2 Cost of Illness Calculation .................................................................................. 116
4.5.3 DALY ................................................................................................................. 120
4.5.4 Sensitivity Analysis ............................................................................................ 123
4.6 Conclusion ................................................................................................................ 127
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5 Results and Discussion ............................................................................................... 128
5.1 Introduction ............................................................................................................... 128
5.2 Intervention Scenario Analysis ................................................................................. 128
5.2.1 Simulation ........................................................................................................... 130
5.3 Food Safety Standard ................................................................................................ 130
5.3.1 Scenarios ............................................................................................................. 133
5.3.2 Ranking of Interventions..................................................................................... 145
5.4 Food safety Standard – Discussion ........................................................................... 149
5.5 Comparing Different Assessment Measures used to assess the Cost-effectiveness of
Interventions ................................................................................................................... 150
5.5.1 Cost-sensitivity Analysis .................................................................................... 157
5.6 Illustrating the Multiple Hurdle Approach ............................................................... 159
5.7 Comparing Results with other Country Level Studies ............................................. 165
5.8 Comparison of Intervention Assessment Measures .................................................. 167
5.9 Conclusion ................................................................................................................ 174
6 Summary of Results and Policy Implications .......................................................... 177
6.1 Introduction ............................................................................................................... 177
6.2 Summary of Methods and Findings .......................................................................... 177
6.3 Policy Implications ................................................................................................... 181
6.3.1 Pareto Optimality ................................................................................................ 182
6.3.2 Measures used to Rank Interventions ................................................................. 184
6.3.3 Feasibility of a Food Safety Standard ................................................................. 185
6.4 Limitations ................................................................................................................ 188
6.5 Recommendations for Future Research .................................................................... 189
7 References ................................................................................................................... 192
Appendices ..................................................................................................................... 208
Appendix A: Letter to Plants .......................................................................................... 208
Appendix B: Chicken Processor Survey ......................................................................... 210
Appendix C: Comparison of different Campylobacter Risk Assessment Models ........ 214
Appendix D: Model ....................................................................................................... 216
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Appendix E: Sensitivity Analysis ................................................................................... 226

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List of Figures
Figure 2-1 Determining the optimal level of food safety ................................................. 13
Figure 2-2 Three Fields of Risk Analysis ......................................................................... 22
Figure 2-3 Burden of illness pyramid ............................................................................... 38
Figure 3-1 Bacteria growth ............................................................................................... 49
Figure 3-2 Case One: Pathogen load at final stage is below the critical value ................. 53
Figure 3-3 Case Two: Pathogen load at final stage is above the critical value ................ 54
Figure 3-4 Case Three: Intervention effort slows down pathogen growth ....................... 55
Figure 3-5 Illustration Stochastic Model ......................................................................... 59
Figure 4-1 Overall Modelling Approach .......................................................................... 69
Figure 4-2 Incidence of Campylobacteriosis, Salmonellosis, Shigellosis and
Verotoxigenic E. Coli in Canada ..................................................................................... 72
Figure 4-3 Per Capita Consumption of Meat in Canada from 1961 to 2006 .................... 73
Figure 4-4 Microbiological Model Overview ................................................................... 77
Figure 4-5 Processing Line of a Typical Poultry Processing Plant .................................. 79
Figure 4-6 Chicken Production and Consumption in Ontario .......................................... 84
Figure 4-7 Triangular Probability Density Function ........................................................ 86
Figure 4-8 Decision tree to determine DALY‘s associated with
Campylobacteriosiscaused by chicken ........................................................................... 122
Figure 5-1 Decision Tree for Intervention Analysis ...................................................... 129
Figure 5-2 Base Scenario ................................................................................................ 135
Figure 5-3 Impact of Chlorine effectiveness, high ......................................................... 137
Figure 5-4 Impact of Chlorine effectiveness, low .......................................................... 138
Figure 5-5 Impact of lactic acid ...................................................................................... 139
Figure 5-6 Impact of ASC............................................................................................... 140
Figure 5-7 Impact of freezing ......................................................................................... 141
Figure 5-8 Impact of irradiation ...................................................................................... 142
Figure 5-9 Probability of achieving a Standard with Interventions ................................ 143
Figure 5-10 Change in Probability of achieving a Standard ........................................... 144
Figure 5-11 Percentage change in standard compliance ................................................. 145
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Figure 5-12 Trade off Curve ........................................................................................... 148
Figure 5-13 Combination of LA&ASC, LA, ASC ......................................................... 161
Figure 5-14 Combination of CL&ASC&Fr, LA&Fr, Cl&Fr ......................................... 162
Figure 5-15 Illustration of the multiple hurdle approach ................................................ 163

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