Background: Susceptibility to exertional heat illness
(EHI) is considered multifactorial in nature. The aims of
this study were to (1) review traditional susceptibility
factors identified in cases of EHI and (2) determine
how they are related to risk of hospitalisation.
Methods: Review of an electronic database of EHI
reported in the British Army between 1 September
2007 and 31 December 2014. Cases were categorised
by demographic, situational and susceptibility
variables. Univariate and multivariate logistic regression
was performed for the OR for hospitalisation by risk
factor.
Results: 361 reports were included in the analysis.
33.5% of cases occurred in hot climates, 34.6% in
temperate climates during summer months and 31.9%
in temperate climates outside of summer months.
Traditional susceptibility factors were reported in 193
but entirely absent from 168 cases. 137 cases (38.0%)
were admitted to hospital. Adjusted OR for
hospitalisation was lower for recruits (OR 0.42, 95% CI
0.18 to 0.99, p<0.05) and for personnel wearing
occlusive dress (OR 0.56, 95% CI 0.34 to 0.93,
p<0.05) or unacclimatised to heat (OR 0.31, 95% CI
0.15 to 0.66, p<0.01).
Conclusions: The global, year-round threat of EHI is
highlighted. Absence of susceptibility factors in nearly
half of reports highlights the challenge of identifying
EHI-prone individuals. Paradoxical association of
traditional susceptibility factors with reduced
hospitalisation risk may reflect the contemporary
contexts in which severe EHI occurs. These findings
also suggest a need for better evidence to inform
guidelines that aim to prevent severe EHI concurrent to
reducing overall morbidity.