Systematic review of gender differences in the epidemiology and risk factors of exertional heat illness and heat tolerance in the armed forces

Objectives This review aimed to describe the epidemiology of all heat-related illnesses in women compared with men in the armed forces and to identify gender-specific risk factors and differences in heat tolerance. Design A systematic review of multiple databases (MEDLINE, Emcare, CINAHL, PsycINFO, Informit and Scopus) was conducted from the inception of the databases to 1 April 2019 using the preferred reporting items for systematic review and meta-analysis guidelines. Eligibility criteria All relevant studies investigating and comparing heat illness and heat tolerance in women and men in the armed forces were included in the review. Results Twenty-four studies were included in the systematic review. The incidence of heat stroke in women ranged from 0.10 to 0.26 per 1000 person-years, while the incidence of heat stroke ranged from 0.22 to 0.48 per 1000 person-years in men. The incidence of other heat illnesses in women compared with men ranged from 1.30 to 2.89 per 1000 person-years versus 0.98 to 1.98 per 1000 person-years. The limited evidence suggests that women had a greater risk of exertional heat illness compared with men. Other gender-specific risk factors were slower run times and body mass index. Although there was a higher proportion of women who were heat intolerant compared with men, this finding needs to be interpreted with caution due to the limited evidence. Conclusion The findings of this review suggest that men experienced a slightly higher incidence of heat stroke than women in the armed forces. In addition, the limited available evidence suggests that a higher proportion of women were heat intolerant and being a female was associated with a greater risk of exertional heat illnesses. Given the limited evidence available, further research is required to investigate the influence of gender differences on heat intolerance and heat illness.