Personal risk factors associated with heat-related illness among new conscripts undergoing basic training in Thailand

Abstract

Cases of exertional heat stroke have been reported every year during basic training for Royal Thai Army (RTA) conscripts. Prevention is an important strategy to reduce the incidence of heat-related illnesses. We conducted a study to identify potential indicators for the prevention and monitoring of heat-related illnesses among military conscripts undergoing basic training in Thailand. All newly inducted RTA conscripts in 5 basic training units in 5 regions in Thailand were invited to participate in a prospective cohort study from May 1 to July 9, 2013. The incidence rate of heat-related illnesses and the incidence rate ratio (IRR) based on a Poisson regression model were used to identify the independent factors associated with heat-related illnesses, daily tympanic (body) temperatures higher than 37.5°C, >3% decreases in body weight in one day, and the production of dark brown urine. Eight hundred and nine men aged 21.4 (±1.13) years were enrolled in this study. The prevalence of a body mass index (BMI) ≥30 kg/m2 was 5.5%. During the study period, 53 subjects (6.6%) representing 3.41/100 person-months (95% confidence interval (CI), 2.55–4.23) developed heat-related illnesses (excluding heat rash), and no subjects experienced heat stroke. The incidence rates of a daily tympanic temperature >37.5°C at least once, body weight loss of >3% per day, and the production of dark brown urine at least once were 8.27/100 person-months (95% CI, 7.69–8.93), 47.91/100 person-months (95% CI, 44.22–51.58), and 682.11/100 person-months (95% CI, 635.49–728.52), respectively. The sole identified independent factor related to the incidence of heat-related illnesses was a BMI ≥30 kg/m2 (adjusted IRR = 2.66, 95% CI, 1.01–7.03). In conclusion, a high BMI was associated with heat-related illnesses among conscripts undergoing basic training in Thailand. Daily monitoring of heat-related illnesses, body temperature, body weight and urine color in each new conscript during basic military training was feasible.

Epidemiology of Exertional Heat Illness in the Military: A Systematic Review of Observational Studies

“…The titles and abstracts were screened, and 1502 articles excluded, leaving 154 articles for full-text review. Data in Table S2 depict that 41 articles were included in the review [ 13 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 ], comprising 29 descriptive and cross-sectional studies [ 13 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 30 , 31 , 32 , 33 , 34 , 35 …”

“…The incidence rate based on the number of participants (prevalence rate) was reported in three studies, while for four studies, the rates of EHI were calculated to obtain the prevalence rate based on the information provided in the articles ( Table 2 ). Overall, the prevalence rates ranged from 0.6% to 9.3% [ 33 , 34 , 35 , 44 , 45 , 50 , 51 ]. Studies published before 2010 reported prevalence rates ranging from 3.2% to 9.3% [ 35 , 44 , 45 ], while studies published from 2010 onwards reported prevalence rates ranging from as low as 0.6 to 6.6% [ 32 , 33 , 34 , 50 , 51 ].…”

“…Overall, the prevalence rates ranged from 0.6% to 9.3% [ 33 , 34 , 35 , 44 , 45 , 50 , 51 ]. Studies published before 2010 reported prevalence rates ranging from 3.2% to 9.3% [ 35 , 44 , 45 ], while studies published from 2010 onwards reported prevalence rates ranging from as low as 0.6 to 6.6% [ 32 , 33 , 34 , 50 , 51 ]. Among studies that used the ICD 9 or 10 codes, the prevalence rates ranged from 0.6% to 1.4% [ 33 , 34 , 50 ], while the rates in studies that did not use the ICD codes ranged from 3.2% to 9.3% [ 35 , 44 , 45 , 51 ].…”

“…Anthropometric factors identified in this review were obesity and overweight. In this review, six studies used body mass index (BMI) as the measure to define obesity and overweight [ 37 , 41 , 49 , 50 , 51 , 59 ], where BMI was classified as underweight (<18.5 kgm −2 ), normal weight (18.5–25.0 kgm −2 ), overweight (25.0–29.9 kgm −2 ), and obese (≥30.0 kgm −2 ). Two other studies used a two-tiered approach to determine obesity which were BMI and percentage body fat.…”

Biobehavioral variation in human water needs: How adaptations, early life environments, and the life course affect body water homeostasis

“…This altered distribution of body fluid may affect homeostatic mechanisms regulating electrolyte balance within and between cells (Thornton, ). The consequences of this have been documented through higher incidences of heat illness reported among army recruits with obesity compared to those without obesity (Nutong et al, ). Moreover, obesity is linked to increased oxidative stress which may lead to chronic kidney disease (Sharma, ).…”