This thesis represents my research work relating to rugby union from 2000 to 2007. During this time I was the Manager of Injury Prevention and Research for the New Zealand Rugby Union (NZRU). The main priorities of this role were to increase understanding of risk factors for rugby injury, to implement preventive measures, and to assess the effect of those preventive measures. The thesis is presented as a series of peer-reviewed, published papers. A key concern of the NZRU when I undertook the role was to decrease the number and severity of spinal cord injuries occurring in New Zealand rugby. The first paper is a review of literature of rugby union injuries to the cervical spine and spinal cord. This paper was published in Sports Medicine, and the knowledge derived there from formed an important element in RugbySmart, which was the nationwide injury prevention partnership between the NZRU and ACC. The second paper, which was published in the British Medical Journal, outlines the effect of RugbySmart on serious spinal injuries in New Zealand. Eight spinal injuries occurred in New Zealand in 2001-2005, whereas the predicted number based on previous incidence was 19 (relative rate 0.46, 95% confidence interval 0.19 to 1.14). The main reason for the decline was a decrease in the number of injuries from scrums, from a predicted number of nine only one was observed (relative rate 0.11; 0.02 to 0.74). Injury prevention initiatives in New Zealand appear to have been successful in areas beyond spinal injuries. The third paper deals with the effect of RugbySmart in general. RugbySmart was associated with a decrease in injury claims per 100,000 players in most areas the programme targeted; the programme had negligible impact on non-targeted injury sites. The decrease in injury claims numbers was supported by results from player behaviour surveys pre- and post-RugbySmart. There was an increase in safe behaviour in the contact situations of tackle, scrum and ruck technique. The fourth paper, which was published in the British Journal of Sports Medicine, examines the effect of mandating mouth guard usage on mouth guard wearing rates and ACC dental injury claim rates. The self reported rate of mouth guard use was 67% of player-weeks in 1993 and 93% in 2003. A total of 2644 claims were reported in 1995. There was a 43% (90% confidence interval 39% to 46%) reduction in dental claims from 1995 to 2003. On the reasonable assumption that the number of players and player-matches remained constant throughout the study period, the relative rate of injury claims for non-wearers versus wearers was 4.6 (90% confidence interval 3.8 to 5.6). In New Zealand the tackle is the facet of play associated number of injuries, and over the past decade tackles have overtaken scrums as the cause of the greatest proportion of spinal injuries. To address the lack of knowledge regarding risk factors for injuries in the tackle, a large scale study of tackles in professional rugby matches was undertaken. In 434 matches, over 140,000 tackles were coded. The impact of the tackle was the most common cause of injury, and the head was the most common site, but an important mechanism of lower limb injuries was loading with the weight of another player. Rates of replacement increased with increasing player speed. The resulting paper was published in the American Journal of Sports Medicine. A commonly cited model of injury causation in sport posits that risk factors for injury can be considered as those related to the athlete (intrinsic) and those related to the activity (extrinsic). To examine the extent to which the activities comprising rugby matches at the international level has changed over time the first match in each Bledisloe Cup series from 1972 to 2004 was coded. Increases in passes, tackles, rucks, tries, and ball-in-play time were associated with the advent of professionalism, whereas there were reductions in the numbers of lineouts, mauls, kicks in play, and in mean participation time per player. Noteworthy time trends were an increase in the number of rucks and a decrease in the number of scrums. With the advent of professionalism, players have become heavier and backs have become taller. A number of articles written to communicate injury prevention messages to rugby union coaches, players and administrators are presented as appendices, along with two peer reviewed papers that closely relate to the thesis, but which I excluded from the thesis proper.

This thesis represents my research work relating to rugby union from 2000 to 2007. During this time I was the Manager of Injury Prevention and Research for the New Zealand Rugby Union (NZRU). The main priorities of this role were to increase understanding of risk factors for rugby injury, to implement preventive measures, and to assess the effect of those preventive measures. The thesis is presented as a series of peer-reviewed, published papers. A key concern of the NZRU when I undertook the role was to decrease the number and severity of spinal cord injuries occurring in New Zealand rugby. The first paper is a review of literature of rugby union injuries to the cervical spine and spinal cord. This paper was published in Sports Medicine, and the knowledge derived there from formed an important element in RugbySmart, which was the nationwide injury prevention partnership between the NZRU and ACC. The second paper, which was published in the British Medical Journal, outlines the effect of RugbySmart on serious spinal injuries in New Zealand. Eight spinal injuries occurred in New Zealand in 2001-2005, whereas the predicted number based on previous incidence was 19 (relative rate 0.46, 95% confidence interval 0.19 to 1.14). The main reason for the decline was a decrease in the number of injuries from scrums, from a predicted number of nine only one was observed (relative rate 0.11; 0.02 to 0.74). Injury prevention initiatives in New Zealand appear to have been successful in areas beyond spinal injuries. The third paper deals with the effect of RugbySmart in general. RugbySmart was associated with a decrease in injury claims per 100,000 players in most areas the programme targeted; the programme had negligible impact on non-targeted injury sites. The decrease in injury claims numbers was supported by results from player behaviour surveys pre- and post-RugbySmart. There was an increase in safe behaviour in the contact situations of tackle, scrum and ruck technique. The fourth paper, which was published in the British Journal of Sports Medicine, examines the effect of mandating mouth guard usage on mouth guard wearing rates and ACC dental injury claim rates. The self reported rate of mouth guard use was 67% of player-weeks in 1993 and 93% in 2003. A total of 2644 claims were reported in 1995. There was a 43% (90% confidence interval 39% to 46%) reduction in dental claims from 1995 to 2003. On the reasonable assumption that the number of players and player-matches remained constant throughout the study period, the relative rate of injury claims for non-wearers versus wearers was 4.6 (90% confidence interval 3.8 to 5.6). In New Zealand the tackle is the facet of play associated number of injuries, and over the past decade tackles have overtaken scrums as the cause of the greatest proportion of spinal injuries. To address the lack of knowledge regarding risk factors for injuries in the tackle, a large scale study of tackles in professional rugby matches was undertaken. In 434 matches, over 140,000 tackles were coded. The impact of the tackle was the most common cause of injury, and the head was the most common site, but an important mechanism of lower limb injuries was loading with the weight of another player. Rates of replacement increased with increasing player speed. The resulting paper was published in the American Journal of Sports Medicine. A commonly cited model of injury causation in sport posits that risk factors for injury can be considered as those related to the athlete (intrinsic) and those related to the activity (extrinsic). To examine the extent to which the activities comprising rugby matches at the international level has changed over time the first match in each Bledisloe Cup series from 1972 to 2004 was coded. Increases in passes, tackles, rucks, tries, and ball-in-play time were associated with the advent of professionalism, whereas there were reductions in the numbers of lineouts, mauls, kicks in play, and in mean participation time per player. Noteworthy time trends were an increase in the number of rucks and a decrease in the number of scrums. With the advent of professionalism, players have become heavier and backs have become taller. A number of articles written to communicate injury prevention messages to rugby union coaches, players and administrators are presented as appendices, along with two peer reviewed papers that closely relate to the thesis, but which I excluded from the thesis proper.

Abstract Background An analysis of Accident Compensation Corporation claims shows “inconsistent and inadequate diagnoses” by health care providers. Diagnostic performance is a result of two independent parameters, namely discrimination (accuracy) and decision (bias). Bias is related to the medical practitioner’s perception of the costs and benefits of making one choice over another. Bias may be statistical, sociological, political, biological or psychological in nature. This study investigated the factors that potentially bias diagnostic decision-making by general practitioners and the subjective value placed on these factors by different stakeholder groups in society. Methods Phase 1 of the study used focus groups of standard setters for general practitioners to identify factors that influenced diagnostic decision-making in general practice. These factors were evaluated for importance and desirability using standard Delphi methodology and Rasch analysis. Phase 2 of the study evaluated the importance and desirability of the factors identified in Phase 1 for influencing decision making as judged by significant health care stakeholder groups in New Zealand. Participant response was via questionnaire analysed by the Rasch Model. Results Thirty-nine factors were identified that potentially biased diagnostic decision-making in general practice. The measurements of, particularly, desirability have high reproducibility across stakeholder groups and high positive loading for the first principal component consistent with construct validity. No stakeholder group identifies factors consistent with Bayes’ theorem of diagnostic reasoning as being the only desirable influence on diagnosis. There is considerable categorical homogeneity between the stakeholder groups GP, GPACC, P, RACCSLT and RACCSST. Conclusions The findings of this and other studies challenge the current biomedical paradigm, indicating a less than Bayesian approach to medical decision-making. A social constructivist model, incorporating non-Bayesian factors into the definition of “illness” versus “disease”, may be more representative of reality. A social constructivist model of medicine is incompatible with the current legislatory and administrative framework within which the Accident Compensation Corporation and a number of other medical organisations operate. / Accident Compensation Corporation of New Zealand

Abstract Background An analysis of Accident Compensation Corporation claims shows “inconsistent and inadequate diagnoses” by health care providers. Diagnostic performance is a result of two independent parameters, namely discrimination (accuracy) and decision (bias). Bias is related to the medical practitioner’s perception of the costs and benefits of making one choice over another. Bias may be statistical, sociological, political, biological or psychological in nature. This study investigated the factors that potentially bias diagnostic decision-making by general practitioners and the subjective value placed on these factors by different stakeholder groups in society. Methods Phase 1 of the study used focus groups of standard setters for general practitioners to identify factors that influenced diagnostic decision-making in general practice. These factors were evaluated for importance and desirability using standard Delphi methodology and Rasch analysis. Phase 2 of the study evaluated the importance and desirability of the factors identified in Phase 1 for influencing decision making as judged by significant health care stakeholder groups in New Zealand. Participant response was via questionnaire analysed by the Rasch Model. Results Thirty-nine factors were identified that potentially biased diagnostic decision-making in general practice. The measurements of, particularly, desirability have high reproducibility across stakeholder groups and high positive loading for the first principal component consistent with construct validity. No stakeholder group identifies factors consistent with Bayes’ theorem of diagnostic reasoning as being the only desirable influence on diagnosis. There is considerable categorical homogeneity between the stakeholder groups GP, GPACC, P, RACCSLT and RACCSST. Conclusions The findings of this and other studies challenge the current biomedical paradigm, indicating a less than Bayesian approach to medical decision-making. A social constructivist model, incorporating non-Bayesian factors into the definition of “illness” versus “disease”, may be more representative of reality. A social constructivist model of medicine is incompatible with the current legislatory and administrative framework within which the Accident Compensation Corporation and a number of other medical organisations operate. / Accident Compensation Corporation of New Zealand

Abstract Background An analysis of Accident Compensation Corporation claims shows “inconsistent and inadequate diagnoses” by health care providers. Diagnostic performance is a result of two independent parameters, namely discrimination (accuracy) and decision (bias). Bias is related to the medical practitioner’s perception of the costs and benefits of making one choice over another. Bias may be statistical, sociological, political, biological or psychological in nature. This study investigated the factors that potentially bias diagnostic decision-making by general practitioners and the subjective value placed on these factors by different stakeholder groups in society. Methods Phase 1 of the study used focus groups of standard setters for general practitioners to identify factors that influenced diagnostic decision-making in general practice. These factors were evaluated for importance and desirability using standard Delphi methodology and Rasch analysis. Phase 2 of the study evaluated the importance and desirability of the factors identified in Phase 1 for influencing decision making as judged by significant health care stakeholder groups in New Zealand. Participant response was via questionnaire analysed by the Rasch Model. Results Thirty-nine factors were identified that potentially biased diagnostic decision-making in general practice. The measurements of, particularly, desirability have high reproducibility across stakeholder groups and high positive loading for the first principal component consistent with construct validity. No stakeholder group identifies factors consistent with Bayes’ theorem of diagnostic reasoning as being the only desirable influence on diagnosis. There is considerable categorical homogeneity between the stakeholder groups GP, GPACC, P, RACCSLT and RACCSST. Conclusions The findings of this and other studies challenge the current biomedical paradigm, indicating a less than Bayesian approach to medical decision-making. A social constructivist model, incorporating non-Bayesian factors into the definition of “illness” versus “disease”, may be more representative of reality. A social constructivist model of medicine is incompatible with the current legislatory and administrative framework within which the Accident Compensation Corporation and a number of other medical organisations operate. / Accident Compensation Corporation of New Zealand

Abstract Background An analysis of Accident Compensation Corporation claims shows “inconsistent and inadequate diagnoses” by health care providers. Diagnostic performance is a result of two independent parameters, namely discrimination (accuracy) and decision (bias). Bias is related to the medical practitioner’s perception of the costs and benefits of making one choice over another. Bias may be statistical, sociological, political, biological or psychological in nature. This study investigated the factors that potentially bias diagnostic decision-making by general practitioners and the subjective value placed on these factors by different stakeholder groups in society. Methods Phase 1 of the study used focus groups of standard setters for general practitioners to identify factors that influenced diagnostic decision-making in general practice. These factors were evaluated for importance and desirability using standard Delphi methodology and Rasch analysis. Phase 2 of the study evaluated the importance and desirability of the factors identified in Phase 1 for influencing decision making as judged by significant health care stakeholder groups in New Zealand. Participant response was via questionnaire analysed by the Rasch Model. Results Thirty-nine factors were identified that potentially biased diagnostic decision-making in general practice. The measurements of, particularly, desirability have high reproducibility across stakeholder groups and high positive loading for the first principal component consistent with construct validity. No stakeholder group identifies factors consistent with Bayes’ theorem of diagnostic reasoning as being the only desirable influence on diagnosis. There is considerable categorical homogeneity between the stakeholder groups GP, GPACC, P, RACCSLT and RACCSST. Conclusions The findings of this and other studies challenge the current biomedical paradigm, indicating a less than Bayesian approach to medical decision-making. A social constructivist model, incorporating non-Bayesian factors into the definition of “illness” versus “disease”, may be more representative of reality. A social constructivist model of medicine is incompatible with the current legislatory and administrative framework within which the Accident Compensation Corporation and a number of other medical organisations operate. / Accident Compensation Corporation of New Zealand

Abstract Background An analysis of Accident Compensation Corporation claims shows “inconsistent and inadequate diagnoses” by health care providers. Diagnostic performance is a result of two independent parameters, namely discrimination (accuracy) and decision (bias). Bias is related to the medical practitioner’s perception of the costs and benefits of making one choice over another. Bias may be statistical, sociological, political, biological or psychological in nature. This study investigated the factors that potentially bias diagnostic decision-making by general practitioners and the subjective value placed on these factors by different stakeholder groups in society. Methods Phase 1 of the study used focus groups of standard setters for general practitioners to identify factors that influenced diagnostic decision-making in general practice. These factors were evaluated for importance and desirability using standard Delphi methodology and Rasch analysis. Phase 2 of the study evaluated the importance and desirability of the factors identified in Phase 1 for influencing decision making as judged by significant health care stakeholder groups in New Zealand. Participant response was via questionnaire analysed by the Rasch Model. Results Thirty-nine factors were identified that potentially biased diagnostic decision-making in general practice. The measurements of, particularly, desirability have high reproducibility across stakeholder groups and high positive loading for the first principal component consistent with construct validity. No stakeholder group identifies factors consistent with Bayes’ theorem of diagnostic reasoning as being the only desirable influence on diagnosis. There is considerable categorical homogeneity between the stakeholder groups GP, GPACC, P, RACCSLT and RACCSST. Conclusions The findings of this and other studies challenge the current biomedical paradigm, indicating a less than Bayesian approach to medical decision-making. A social constructivist model, incorporating non-Bayesian factors into the definition of “illness” versus “disease”, may be more representative of reality. A social constructivist model of medicine is incompatible with the current legislatory and administrative framework within which the Accident Compensation Corporation and a number of other medical organisations operate. / Accident Compensation Corporation of New Zealand