ANALYTICAL CLINICAL STUDIES
Profiling the careers of Thoroughbred horses racing in Hong Kong between 2000 and 2010
Reasons for performing study
Research in Thoroughbred racehorses is often specific to horses from a given racing population or region. In order to investigate trends in racehorse careers across populations accurately, population-specific benchmarks for performance outcomes must be established.
To provide summary statistics for performance outcomes for Thoroughbreds racing in Hong Kong between 2000 and 2010 and to document and provide evidence on the current differences in racing careers across sexes and regions of origin for horses racing in Hong Kong.
Performance data on the population of Thoroughbreds racing in Hong Kong between 3 September 2000 and 12 March 2011 (n = 4950) were acquired and used to describe and compare the careers of Thoroughbred racehorses in Hong Kong.
Career length, number of career starts and number of spells from racing per year were evaluated. Kaplan–Meier survival curves, stratified by sex, age group, country of origin and region of origin were produced for career length. A Cox's proportional hazards model was fitted to assess factors influencing the risk of retirement from racing in Hong Kong.
Log-rank tests for equality of career length survivor functions showed significant differences (P<0.001) across sexes, age groups, countries of origin and regions of origin. An increased age at first start in Hong Kong tended to increase the hazard rate for retirement from racing in Hong Kong, whereas greater earnings per race and originating from Europe tended to reduce the hazard rate for racing retirement.
Conclusions and potential relevance
Differences in career outcomes within a racing population appear to be influenced partly by the region from which a horse originates, with specific effects on each performance outcome also varying between regions. Future research should take into account these potential differences when comparing results across populations.
The Summary is available in Chinese – see Supporting information.