PURPOSE: To evaluate differences in injury frequency and severity between two different heat participation policies in South Carolina high school and collegiate athletics.
METHODS: Retrospective cohort study of Division II collegiate & high school athletes looking at injury frequency & severity between 2 different heat participation policies. Fifty middle & high schools as well as 2 Division II colleges with a total of 16,832 athletes were investigated over 3 years. Inclusion criteria were reported heat illnesses between July 1 & November 30^th for 12 outdoor sports resulting in 86 injuries that were analyzed. Chi square analysis was used to compare injury frequency & severity between no outdoor workouts with a wet bulb globe temperature (WBGT)> 90 (policy 1) versus WBGT> 92 (policy 2).
RESULTS: For policy 1 there was a mean of 31 heat illnesses/year with an average of 16 days for illness resolution. For policy 2 there was a mean of 24 heat illnesses/year but the average of 41 days for illness resolution was significantly higher (p=0.02). Grading heat illness severity was based on guidelines developed by Rauh et. al. Mild to moderate injury was defined as 0-21 days for return to activity while severe injury >21 days for return to activity. With policy 1, 4.8% of heat illnesses met severe criteria while 20.8% of heat illnesses in policy 2 were severe showing an odds ratio of heat illness with policy 2 is 5.2 times higher than policy 1 (OR 5.2, 95% CI 1.1-23.7). Conversely the percentage of mild to moderate illness was statistically lower with policy 2 compared to policy 1 (p=0.022) suggesting that policy 2 resulted in more severe heat illness. Policy 1 was in place for several years with no record of EMS transport for heat illnesses however within the first season of policy 2, there was 3 athletes transported. The average age at time of injury was 16 years old & not statistically different between policies. There was an average of 45 minutes of practice per week lost with the WBGT cutoff of 90 compared to cutoff of 92.
CONCLUSIONS: Although the total number of heat illnesses did not change between policies, there was a statistically significant increase in severity of illness & time for return to sport with raising the WBGT participation cutoff from 90 to 92. Our data suggests that a cutoff of 90 reduces the frequency of severe heat illness in athletes.