Methods
To develop the framework of descriptors and definitions and reach a consensus, a two-step process was applied as previously described by Hendricks et al21 with further consideration of the Conducting and REporting DElphi Studies guidelines.27 For the first step, a systematic search of the literature was performed. Specific search terms were used to identify peer-reviewed articles in three electronic databases: PubMed, Scopus and Web of Science. The search terms were ‘horse racing’ in the title, keywords or abstract linked in any way to the following terms: ‘video analysis’, ‘jockey injury risk factors’, ‘jockey fall risk factors’, ‘jockey catastrophic injury’, ‘jockey injury mechanism’, ‘jockey injury incidence’, ‘jockey fall’, ‘jockey video analysis’ or ‘jockey injury’ anywhere in the text with a total of nine searches performed for each database. For example, in Scopus, the full search strategy for the term ‘jockey injury’ was: (TITLE-ABS-KEY (horse AND racing) AND ALL (jockey injury) PUBYEAR<2021 LANGUAGE (English) SRCTYPE (j). If the term ‘jockey’ was omitted from the search criteria, the database yielded a heavy dominance in horse-related articles. The results of all nine database searches were merged and duplicates removed. The time frame for the literature search included any article published up to 1 November 2020. The inclusion criteria were as follows: the article needed to be published in a peer-reviewed journal in English and needed to discuss the risk factors related to jockey injuries and jockey and horse falls in horse racing. The inclusion criteria were applied at the title, abstract and full-text levels. Any article not meeting the inclusion criteria was excluded from further review. The results from all three databases were merged, and duplicates were removed, yielding a total of 87 articles that documented the potential risk factors of falls and jockey injuries. Figure 1 summarises the systematic literature search.
Figure 1Flow diagram of literature search. Specific search terms were used to identify peer-reviewed articles in three electronic databases: PubMed, Scopus and Web of Science. The search terms were ‘horse racing’ in the title, keywords or abstract linked in any way to the following terms: ‘video analysis’, ‘jockey injury risk factors’, ‘jockey fall risk factors’, ‘jockey catastrophic injury’, ‘jockey injury mechanism’, ‘jockey injury incidence’, ‘jockey fall’, ‘jockey video analysis’ or ‘jockey injury’ anywhere in the text with a total of nine searches performed for each database. The results of all nine database searches were merged and duplicates removed. The inclusion criteria were as follows: the article needed to be published in a peer-reviewed journal in English and needed to discuss the risk factors related to jockey injuries and jockey and horse falls in horse racing. The inclusion criteria were applied at title, abstract and full-text level, any article not meeting the inclusion criteria was excluded from further review. The results from all three databases were merged and duplicates removed yielding a total of 87 articles that documented the potential risk factors of falls and jockey injuries.
In step 2, the purposive recruitment of 17 steering committee members was conducted from within the British horse racing industry’s stakeholders, whose focus is on the care and well-being of professional jockeys and the industry workforce. This included representation from the jockeys’ union (Professional Jockeys Association), British horse racing’s regulatory body (British Horseracing Authority) and the jockey welfare (Injured Jockeys Fund) and training agencies (British Racing School), along with experienced medical professionals (Consultant Spinal Surgeon, Horse Racing Medical Officers) with extensive expertise in the diagnosis and management of jockey injuries. The steering committee also benefited from the representation of the British Equestrian Trade Association, which set the safety standard for body protectors used by equestrians. Finally, eight current professional jockeys (five men, three women) of varying competitive experience from both flat and jump subdisciplines also joined the steering committee.
The authorship group consisted of academics in biomechanics (DC and PM) and epidemiology (KS) and a practising physiotherapist (DL) experienced in the management and rehabilitation of jockey injuries.
Once the steering committee had been established, the development and consensus of descriptors and definitions were sought using a modified Delphi consensus method.27–29 The iterative process of the Delphi consensus method facilitated the development of the analysis framework while overcoming the geographical30 and logistical restrictions experienced due to the COVID-19 pandemic. Furthermore, this method of engagement also provided all steering committee members with the equal opportunity to contribute regardless of social status, seniority or interpersonal skills.27 31
A total of four Delphi rounds were conducted. For the first Delphi round, steering committee members completed an online questionnaire consisting of two open-ended questions: Q1. What do you think are the risk factors of falls in horse racing? and Q2. What do you think are the risk factors of injuries in horse racing? The authorship group then combined the risk factors proposed by the steering committee with the risk factors identified through the search strategy and drafted appropriate descriptors and definitions of such risk factors, and key features of a horse or jockey fall in horse racing.
The resultant framework of descriptors and definitions was structured into subsections to consider six discrete phases of an inciting event (ie, fall/unseat). These included the following:
Situational descriptors—environmental conditions prior to/under which the inciting event occurred. Including location, surface type, obstacles (where relevant), competitive scenario, jockey, horse and opponent behaviour.
Gross fall descriptors—obvious characteristics of a fall, including the type of inciting event, for example, fall or unseating.
Flight phase descriptors—specific biomechanical characteristics of the flight/fall phase prior to jockey sustaining impact.
Contact/impact occurrence descriptors—sequence and characteristics of impacts sustained during fall/inciting event.
Axial skeleton descriptors—specific characteristics involving the axial skeleton during the fall/inciting event.
Secondary impact/recovery descriptors—jockey behaviour and characteristics of any subsequent impact sustained and the recovery immediately following a fall/inciting event.
For subsequent Delphi rounds (two–four), the steering committee members convened via teleconference and examined the framework of proposed descriptors and definitions, rating their level of agreement for each on a 5-point Likert scale (1: strongly disagree; 2: disagree; 3: neither agree nor disagree; 4: agree; 5: strongly agree).32 An online platform (https://www.onlinesurveys.ac.uk/) was used to capture the agreement ratings and any anonymous comments or suggestions. The mean level of agreement (±95% CI) was calculated by summing the ratings and dividing this by the total number of responses. The consensus threshold was determined a priori to be 4/5 (80%). Descriptors and definitions failing to meet the consensus threshold and any anonymous comments were discussed, and any modifications or additions proposed were considered in each subsequent Delphi round. Once a consensus had been achieved for each of the descriptors and definitions, the framework composition was complete. The level of agreement for each of the six framework subsections is reported in the Results section.
To maximise objectivity and reliability and to minimise any ambiguity that might result in coding inaccuracies,22 26 33 three coders experienced in the analysis of human and equine movement and behaviour convened and reviewed the clarity and utilisation of the operational definitions of each analysis framework descriptor. Video footage of 20 horse racing falls (10 jump/10 flat) chosen at random from the British Horseracing Authority video archive was analysed using the video analysis framework. Coding decisions were discussed in an open forum with minimal changes deemed necessary. A single descriptor was removed from the framework due to the varying visibility of furlong markers and race start positions; therefore, coders were unable to consistently identify the distance covered prior to a fall/inciting event from the video footage alone. Furthermore, a strong preference towards coding the horse and jockey’s position in a race by grouping rather than expressed numerically was held by all analysts. While identifying position in a race is possible numerically, this requires greater time and manipulation of video footage, particularly when runners are dispersed in a race.
Finally, as not all steering committee members were available during each round, all members were offered the opportunity to review the analysis framework in its entirety and provide their definitive approval.